brokk_bifrost_cpp/

structural.rs

//! C++ structural spec for `query_code`.

use brokk_bifrost_core::analyzer::common::try_node_source_text as node_text;
use brokk_bifrost_core::analyzer::statement_facts::StatementFactKind;
use brokk_bifrost_core::analyzer::structural::adapter_helpers::{
    CalleeSpineStep, attach_positional_argument_roles, attach_role_with_derived_name,
    attach_terminal_callee, field_name_in_parent, first_named_child, terminal_callee_leaf,
    unquoted_string_content_span,
};
use brokk_bifrost_core::analyzer::structural::callable::{
    CallKind, CallShapeCoverage, CallSiteContext, CallSiteFacts,
};
use brokk_bifrost_core::analyzer::structural::edges::{
    INVERSE_REFERENCE_EDGE_SUPPORT, ReferenceEdgeSupport,
};
use brokk_bifrost_core::analyzer::structural::facts::Span;
use brokk_bifrost_core::analyzer::structural::kinds::{NormalizedKind, Role};
use brokk_bifrost_core::analyzer::structural::materialization::{
    CPP_MATERIALIZATION_SUPPORT, DeclarationMaterializationSupport,
};
use brokk_bifrost_core::analyzer::structural::occurrences::{
    OccurrenceRole, OccurrenceRoleSupport,
};
use brokk_bifrost_core::analyzer::structural::resolution::{
    BindingActivation, BindingKind, EnvironmentAxis, HoistingClass, LexicalEnvironmentSupport,
    ScopeFormation, default_scope_formation,
};
use brokk_bifrost_core::analyzer::structural::result_use::{
    CallResultUse, CallResultUseIndex, CallResultUseOpenReason, CallResultUseSite,
    IntentionalDiscardKind,
};
use brokk_bifrost_core::analyzer::structural::routes::{
    IdentityAxis, IdentityRouteSupport, RouteHopKind,
};
use brokk_bifrost_core::analyzer::structural::spec::{RoleSink, StructuralSpec};
use brokk_bifrost_core::analyzer::tree_walk::{ParentIndex, named_children_iter, node_range};
use brokk_bifrost_core::analyzer::{Language, Range};
use brokk_bifrost_core::hash::HashSet;
use tree_sitter::Node;

#[derive(Debug, Default)]
pub struct CppStructuralSpec;

pub static CPP_STRUCTURAL_SPEC: CppStructuralSpec = CppStructuralSpec;

/// Whether this is a C++ preprocessor conditional node.
///
/// The linked tree-sitter-cpp grammar uses `preproc_ifdef` for both `#ifdef`
/// and `#ifndef`; `preproc_ifndef` remains accepted for trees that expose it
/// as a distinct node kind.
pub(crate) fn is_cpp_preprocessor_conditional(node: Node<'_>) -> bool {
    matches!(
        node.kind(),
        "preproc_if"
            | "preproc_ifdef"
            | "preproc_ifndef"
            | "preproc_elif"
            | "preproc_elifdef"
            | "preproc_else"
    )
}

/// Classify one exact C or C++ call expression.  The C grammar is the same
/// parser route as C++, so the syntax classifier deliberately does not use a
/// source-file extension or a text-search fallback.
pub fn cpp_call_result_use(call: Node<'_>, source: &str) -> CallResultUseSite {
    let default = if !matches!(call.kind(), "call_expression" | "new_expression")
        || call.has_error()
        || has_recovery_ancestor(call)
    {
        CallResultUse::Open(CallResultUseOpenReason::RecoveredSyntax)
    } else if has_deferred_ancestor(call) {
        CallResultUse::Open(CallResultUseOpenReason::DeferredContext)
    } else {
        let mut expression = call;
        loop {
            let Some(parent) = expression.parent() else {
                break CallResultUse::Open(CallResultUseOpenReason::UnclassifiedSyntax);
            };
            if parent.is_error() || parent.is_missing() {
                break CallResultUse::Open(CallResultUseOpenReason::RecoveredSyntax);
            }
            match parent.kind() {
                "parenthesized_expression" | "comma_expression"
                    if parent
                        .named_children(&mut parent.walk())
                        .any(|child| child.id() == expression.id()) =>
                {
                    expression = parent;
                }
                "expression_statement"
                    if parent
                        .named_children(&mut parent.walk())
                        .any(|child| child.id() == expression.id()) =>
                {
                    break CallResultUse::Discarded;
                }
                "for_statement"
                    if matches!(
                        field_name_in_parent(parent, expression),
                        Some("initializer" | "update")
                    ) =>
                {
                    break CallResultUse::Discarded;
                }
                "cast_expression"
                    if field_name_in_parent(parent, expression) == Some("value")
                        && parent
                            .child_by_field_name("type")
                            .is_some_and(|type_node| cpp_type_is_void(type_node, source)) =>
                {
                    break CallResultUse::IntentionalDiscard(IntentionalDiscardKind::CppVoidCast);
                }
                "argument_list"
                    if parent
                        .parent()
                        .is_some_and(|outer_call| cpp_static_cast_to_void(outer_call, source)) =>
                {
                    break CallResultUse::IntentionalDiscard(IntentionalDiscardKind::CppVoidCast);
                }
                "lambda_expression" => {
                    break CallResultUse::Open(CallResultUseOpenReason::DeferredContext);
                }
                _ => break CallResultUse::Consumed,
            }
        }
    };
    CallResultUseSite::new(call.start_byte(), call.end_byte(), default)
}

fn cpp_type_is_void(type_node: Node<'_>, source: &str) -> bool {
    let base = match type_node.kind() {
        "type_descriptor" if type_node.child_by_field_name("declarator").is_none() => {
            type_node.child_by_field_name("type")
        }
        "primitive_type" => Some(type_node),
        _ => None,
    };
    base.is_some_and(|base| {
        base.kind() == "primitive_type" && node_text(base, source) == Some("void")
    })
}

fn has_recovery_ancestor(mut node: Node<'_>) -> bool {
    while let Some(parent) = node.parent() {
        if parent.is_error() || parent.is_missing() {
            return true;
        }
        node = parent;
    }
    false
}

fn has_deferred_ancestor(mut node: Node<'_>) -> bool {
    while let Some(parent) = node.parent() {
        if parent.kind() == "lambda_expression" {
            return true;
        }
        node = parent;
    }
    false
}

fn cpp_static_cast_to_void(call: Node<'_>, source: &str) -> bool {
    if call.kind() != "call_expression" {
        return false;
    }
    let Some(function) = call.child_by_field_name("function") else {
        return false;
    };
    if function.kind() != "template_function"
        || function
            .child_by_field_name("name")
            .and_then(|name| node_text(name, source))
            != Some("static_cast")
    {
        return false;
    }
    function
        .child_by_field_name("arguments")
        .and_then(|arguments| arguments.named_child(0))
        .is_some_and(|type_node| cpp_type_is_void(type_node, source))
}

fn cpp_cast_call(call: Node<'_>, source: &str) -> bool {
    let Some(function) = call.child_by_field_name("function") else {
        return false;
    };
    if function.kind() != "template_function" {
        return false;
    }
    matches!(
        function
            .child_by_field_name("name")
            .and_then(|name| node_text(name, source)),
        Some("static_cast" | "reinterpret_cast" | "const_cast" | "dynamic_cast")
    )
}

/// One source-snapshot index of exact C/C++ call spans.
#[derive(Debug, Clone)]
pub struct CppCallResultUseIndex {
    inner: CallResultUseIndex,
}

impl CppCallResultUseIndex {
    pub fn new(root: Node<'_>, source: &str) -> Self {
        let mut sites = Vec::new();
        let mut stack = vec![root];
        while let Some(node) = stack.pop() {
            if matches!(node.kind(), "call_expression" | "new_expression")
                && !cpp_cast_call(node, source)
            {
                sites.push(cpp_call_result_use(node, source));
            }
            for index in (0..node.named_child_count()).rev() {
                stack.push(node.named_child(index).expect("named child exists"));
            }
        }
        Self {
            inner: CallResultUseIndex::new(sites),
        }
    }

    pub fn at_span(
        &self,
        start_byte: usize,
        end_byte: usize,
    ) -> Result<&CallResultUseSite, CallResultUseOpenReason> {
        self.inner.at_span(start_byte, end_byte)
    }

    pub fn sites(&self) -> &[CallResultUseSite] {
        self.inner.sites()
    }
}

pub const CPP_KIND_TABLE: &[(&str, NormalizedKind)] = &[
    ("comment", NormalizedKind::Comment),
    ("call_expression", NormalizedKind::Call),
    ("new_expression", NormalizedKind::Call),
    ("field_expression", NormalizedKind::FieldAccess),
    ("function_definition", NormalizedKind::Function),
    ("lambda_expression", NormalizedKind::Lambda),
    ("class_specifier", NormalizedKind::Class),
    ("struct_specifier", NormalizedKind::Class),
    ("union_specifier", NormalizedKind::Class),
    ("alias_declaration", NormalizedKind::Declaration),
    ("namespace_definition", NormalizedKind::Module),
    ("assignment_expression", NormalizedKind::Assignment),
    ("init_declarator", NormalizedKind::Assignment),
    ("preproc_include", NormalizedKind::Import),
    ("identifier", NormalizedKind::Identifier),
    ("field_identifier", NormalizedKind::Identifier),
    ("namespace_identifier", NormalizedKind::Identifier),
    ("qualified_identifier", NormalizedKind::Identifier),
    ("type_identifier", NormalizedKind::Identifier),
    ("template_function", NormalizedKind::Identifier),
    ("template_method", NormalizedKind::Identifier),
    ("template_type", NormalizedKind::Identifier),
    ("dependent_name", NormalizedKind::Identifier),
    ("destructor_name", NormalizedKind::Identifier),
    ("operator_name", NormalizedKind::Identifier),
    ("primitive_type", NormalizedKind::Identifier),
    ("char_literal", NormalizedKind::StringLiteral),
    ("string_literal", NormalizedKind::StringLiteral),
    ("raw_string_literal", NormalizedKind::StringLiteral),
    ("number_literal", NormalizedKind::NumericLiteral),
    ("true", NormalizedKind::BooleanLiteral),
    ("false", NormalizedKind::BooleanLiteral),
    ("null", NormalizedKind::NullLiteral),
    ("return_statement", NormalizedKind::Return),
    ("throw_statement", NormalizedKind::Throw),
    ("catch_clause", NormalizedKind::Catch),
    ("if_statement", NormalizedKind::If),
    ("for_statement", NormalizedKind::Loop),
    ("for_range_loop", NormalizedKind::Loop),
    ("compound_statement", NormalizedKind::Block),
    ("switch_statement", NormalizedKind::Switch),
    ("case_statement", NormalizedKind::Case),
    ("labeled_statement", NormalizedKind::Label),
    ("goto_statement", NormalizedKind::Goto),
    ("break_statement", NormalizedKind::Break),
    ("continue_statement", NormalizedKind::Continue),
    ("while_statement", NormalizedKind::WhileLoop),
    ("do_statement", NormalizedKind::WhileLoop),
];

fn cpp_escape_codepoint(digits: &str, radix: u32, byte_escape: bool) -> Option<char> {
    let value = u32::from_str_radix(digits, radix).ok()?;
    if byte_escape && value > 0x7f {
        return None;
    }
    char::from_u32(value)
}

fn cpp_cooked_string_escape(escape: &str) -> Option<Option<char>> {
    let escaped = escape.strip_prefix('\\')?;
    if matches!(escaped, "\n" | "\r\n") {
        return Some(None);
    }
    let character = match escaped {
        "a" => '\x07',
        "b" => '\x08',
        "f" => '\x0c',
        "n" => '\n',
        "r" => '\r',
        "t" => '\t',
        "v" => '\x0b',
        "0" => '\0',
        "\\" => '\\',
        "'" => '\'',
        "\"" => '\"',
        "?" => '?',
        _ if escaped.starts_with('x') => {
            let digits = escaped.get(1..)?;
            (!digits.is_empty()
                && digits.len() <= 4
                && digits.bytes().all(|byte| byte.is_ascii_hexdigit()))
            .then_some(())?;
            cpp_escape_codepoint(digits, 16, true)?
        }
        _ if escaped.starts_with('u') => {
            let digits = escaped.get(1..)?;
            (digits.len() == 4 && digits.bytes().all(|byte| byte.is_ascii_hexdigit()))
                .then_some(())?;
            cpp_escape_codepoint(digits, 16, false)?
        }
        _ if escaped.starts_with('U') => {
            let digits = escaped.get(1..)?;
            (digits.len() == 8 && digits.bytes().all(|byte| byte.is_ascii_hexdigit()))
                .then_some(())?;
            cpp_escape_codepoint(digits, 16, false)?
        }
        _ if escaped.len() <= 3 && escaped.bytes().all(|byte| (b'0'..=b'7').contains(&byte)) => {
            cpp_escape_codepoint(escaped, 8, true)?
        }
        _ => return None,
    };
    Some(Some(character))
}

fn cpp_string_literal_value(node: Node<'_>, source: &str) -> Option<String> {
    let spelling = node_text(node, source)?;
    match node.kind() {
        "string_literal" => {
            // Wide and UTF-prefixed literals have implementation-specific code
            // unit encodings. Only the ordinary narrow form has a portable
            // decoded UTF-8 value for this fact axis.
            if !spelling.starts_with('"') {
                return None;
            }
            let mut decoded = String::new();
            let mut cursor = node.walk();
            for child in node.named_children(&mut cursor) {
                let text = node_text(child, source)?;
                match child.kind() {
                    "string_content" => decoded.push_str(text),
                    "escape_sequence" => {
                        if let Some(character) = cpp_cooked_string_escape(text)? {
                            decoded.push(character);
                        }
                    }
                    _ => return None,
                }
            }
            Some(decoded)
        }
        "raw_string_literal" => {
            if !spelling.starts_with("R\"") {
                return None;
            }
            let mut content = None;
            let mut cursor = node.walk();
            for child in node.named_children(&mut cursor) {
                match child.kind() {
                    "raw_string_content" => {
                        if content.is_some() {
                            return None;
                        }
                        content = Some(node_text(child, source)?);
                    }
                    "raw_string_delimiter" => {}
                    _ => return None,
                }
            }
            content.map(str::to_owned)
        }
        _ => None,
    }
}

fn condition_expression(node: Node<'_>) -> Option<Node<'_>> {
    let condition = node.child_by_field_name("condition")?;
    if condition.kind() == "condition_clause" {
        condition
            .child_by_field_name("value")
            .or_else(|| condition.named_child(0))
    } else {
        Some(condition)
    }
}

/// Declaration evidence retained only while classifying one switch.
#[derive(Clone, Copy)]
struct CppSwitchDeclaration<'tree> {
    type_node: Node<'tree>,
    declarator: Node<'tree>,
}

fn cpp_switch_scope(node: Node<'_>) -> bool {
    matches!(
        node.kind(),
        "compound_statement"
            | "for_statement"
            | "for_range_loop"
            | "if_statement"
            | "switch_statement"
            | "while_statement"
            | "catch_clause"
    )
}

fn cpp_switch_local_declaration<'tree>(
    switch: Node<'tree>,
    name: &str,
    source: &str,
) -> Option<CppSwitchDeclaration<'tree>> {
    let condition = condition_expression(switch)?;
    let function = std::iter::successors(switch.parent(), |node| node.parent())
        .find(|node| matches!(node.kind(), "function_definition" | "lambda_expression"))?;
    enum Step<'tree> {
        Enter(Node<'tree>),
        LeaveScope,
    }
    enum Binding<'tree> {
        Unknown,
        Declaration(CppSwitchDeclaration<'tree>),
    }
    let mut stack = vec![Step::Enter(function)];
    // Only the requested identifier is retained at each lexical tier.
    let mut scopes: Vec<Option<Binding<'tree>>> = vec![None];
    while let Some(step) = stack.pop() {
        let node = match step {
            Step::LeaveScope => {
                scopes.pop().expect("entered scope");
                continue;
            }
            Step::Enter(node) => node,
        };
        if node == condition {
            return scopes.iter().rev().find_map(Option::as_ref).and_then(
                |binding| match binding {
                    Binding::Unknown => None,
                    Binding::Declaration(declaration) => Some(*declaration),
                },
            );
        }
        if node != function
            && matches!(
                node.kind(),
                "function_definition"
                    | "lambda_expression"
                    | "class_specifier"
                    | "struct_specifier"
                    | "union_specifier"
                    | "enum_specifier"
            )
        {
            continue;
        }
        if cpp_switch_scope(node) {
            scopes.push(None);
            stack.push(Step::LeaveScope);
        }
        if node.kind() == "declaration" {
            for declarator in node.children_by_field_name("declarator", &mut node.walk()) {
                if declarator_name_node(declarator).and_then(|node| node_text(node, source))
                    == Some(name)
                {
                    // Prototypes and unsupported declarators also hide names.
                    *scopes.last_mut().expect("function scope") = Some(Binding::Unknown);
                }
            }
        }
        if node.kind() == "identifier"
            && node_text(node, source) == Some(name)
            && let Some(owner) = cpp_binder_owner(node, |node| node.parent(), field_name_in_parent)
        {
            let declaration = match owner {
                CppBinderOwner::Local(declarator) => {
                    let owner = std::iter::successors(declarator.parent(), |node| node.parent())
                        .find(|node| node.kind() == "declaration")
                        .expect("local binder declaration");
                    owner
                        .child_by_field_name("type")
                        .map(|type_node| CppSwitchDeclaration {
                            type_node,
                            declarator,
                        })
                }
                CppBinderOwner::Parameter => {
                    let owner = std::iter::successors(node.parent(), |node| node.parent())
                        .find(|node| {
                            matches!(
                                node.kind(),
                                "parameter_declaration"
                                    | "optional_parameter_declaration"
                                    | "variadic_parameter_declaration"
                            )
                        })
                        .expect("parameter binder declaration");
                    owner
                        .child_by_field_name("type")
                        .zip(owner.child_by_field_name("declarator"))
                        .map(|(type_node, declarator)| CppSwitchDeclaration {
                            type_node,
                            declarator,
                        })
                }
                CppBinderOwner::RangeFor(owner) => owner
                    .child_by_field_name("type")
                    .zip(owner.child_by_field_name("declarator"))
                    .map(|(type_node, declarator)| CppSwitchDeclaration {
                        type_node,
                        declarator,
                    }),
                _ => None,
            };
            // An unknown inner binding must not fall through to a parameter.
            *scopes.last_mut().expect("function scope") =
                Some(declaration.map_or(Binding::Unknown, Binding::Declaration));
        }
        for index in (0..node.named_child_count()).rev() {
            stack.push(Step::Enter(node.named_child(index).expect("named child")));
        }
    }
    None
}

/// Search one lexical type tier, descending into a named scope only when the
/// written qualification selects it. Aliases are barriers, not enum evidence.
fn cpp_switch_type_in_scope<'tree>(
    scope: Node<'tree>,
    path: &[String],
    before: usize,
    source: &str,
) -> Option<Node<'tree>> {
    use crate::declarations::cpp_structured_type_path;
    let mut stack = vec![(scope, 0)];
    let mut found = None;
    let mut unresolved_import = None;
    while let Some((node, component)) = stack.pop() {
        if node.start_byte() >= before {
            continue;
        }
        if node != scope {
            if node.kind() == "using_declaration" {
                let imports_namespace = (0..node.child_count())
                    .any(|index| node.child(index).expect("child").kind() == "namespace");
                let imported = first_named_child(node)
                    .and_then(declarator_name_node)
                    .and_then(|name| node_text(name, source));
                if imports_namespace || imported == Some(path[component].as_str()) {
                    unresolved_import = Some(node);
                }
                continue;
            }
            let named_type = matches!(
                node.kind(),
                "enum_specifier"
                    | "class_specifier"
                    | "struct_specifier"
                    | "union_specifier"
                    | "namespace_definition"
                    | "namespace_alias_definition"
                    | "alias_declaration"
                    | "type_definition"
                    | "type_parameter_declaration"
                    | "variadic_type_parameter_declaration"
            );
            if named_type {
                let names = if node.kind() == "type_definition" {
                    node.children_by_field_name("declarator", &mut node.walk())
                        .filter_map(declarator_name_node)
                        .filter_map(|name| cpp_structured_type_path(name, source))
                        .collect::<Vec<_>>()
                } else if matches!(
                    node.kind(),
                    "type_parameter_declaration" | "variadic_type_parameter_declaration"
                ) {
                    first_named_child(node)
                        .and_then(|name| cpp_structured_type_path(name, source))
                        .into_iter()
                        .collect()
                } else {
                    node.child_by_field_name("name")
                        .and_then(|name| {
                            // A C++17 nested namespace has a different grammar
                            // wrapper from a qualified type name.
                            let mut stack = vec![name];
                            let mut path = Vec::new();
                            while let Some(part) = stack.pop() {
                                if part.kind() == "nested_namespace_specifier" {
                                    for index in (0..part.named_child_count()).rev() {
                                        stack.push(
                                            part.named_child(index).expect("namespace component"),
                                        );
                                    }
                                } else {
                                    path.extend(cpp_structured_type_path(part, source)?);
                                }
                            }
                            Some(path)
                        })
                        .into_iter()
                        .collect()
                };
                for name in names {
                    if path[component..].starts_with(&name) {
                        let next = component + name.len();
                        if next < path.len()
                            && let Some(body) = node.child_by_field_name("body")
                        {
                            stack.push((body, next));
                        } else if found.is_none_or(|previous: Node<'_>| {
                            previous.start_byte() < node.start_byte()
                        }) {
                            // An alias/forward declaration cannot supply the
                            // rest of a qualification and must block fallback.
                            found = Some(node);
                        }
                    }
                }
                continue;
            }
            if cpp_switch_scope(node)
                || matches!(node.kind(), "function_definition" | "lambda_expression")
            {
                continue;
            }
        }
        for index in (0..node.named_child_count()).rev() {
            stack.push((node.named_child(index).expect("named child"), component));
        }
    }
    found.or(unresolved_import)
}

fn cpp_switch_named_type<'tree>(type_node: Node<'tree>, source: &str) -> Option<Node<'tree>> {
    use crate::declarations::cpp_structured_type_path;
    if type_node.kind() == "enum_specifier"
        && type_node.child_by_field_name("body").is_some()
        && type_node.child_by_field_name("name").is_some()
    {
        return Some(type_node);
    }
    if matches!(
        type_node.kind(),
        "class_specifier" | "struct_specifier" | "union_specifier"
    ) && type_node.child_by_field_name("body").is_some()
    {
        return Some(type_node);
    }
    let name = if matches!(
        type_node.kind(),
        "enum_specifier" | "class_specifier" | "struct_specifier" | "union_specifier"
    ) {
        type_node.child_by_field_name("name")?
    } else {
        type_node
    };
    // Template arguments and dependent types require semantic resolution.
    let mut stack = vec![name];
    while let Some(node) = stack.pop() {
        if !matches!(
            node.kind(),
            "type_identifier"
                | "identifier"
                | "namespace_identifier"
                | "qualified_identifier"
                | "scoped_identifier"
                | "scoped_type_identifier"
        ) {
            return None;
        }
        stack.extend(named_children_iter(node).filter(|node| !node.is_extra()));
    }
    let path = cpp_structured_type_path(name, source)?;
    let global = name.child(0).is_some_and(|child| child.kind() == "::");
    for scope in std::iter::successors(type_node.parent(), |node| node.parent()) {
        if !(cpp_switch_scope(scope)
            || matches!(
                scope.kind(),
                "function_definition"
                    | "template_declaration"
                    | "namespace_definition"
                    | "class_specifier"
                    | "struct_specifier"
                    | "union_specifier"
                    | "translation_unit"
            ))
            || (global && scope.kind() != "translation_unit")
        {
            continue;
        }
        if let Some(declaration) =
            cpp_switch_type_in_scope(scope, &path, type_node.start_byte(), source)
        {
            return Some(declaration);
        }
        if !global
            && matches!(
                scope.kind(),
                "class_specifier" | "struct_specifier" | "union_specifier"
            )
        {
            // Inherited names and complete-class lookup can hide an outer
            // enum even without an earlier declaration in the class body.
            if named_children_iter(scope).any(|node| node.kind() == "base_class_clause")
                || cpp_switch_type_in_scope(scope, &path, usize::MAX, source)
                    .is_some_and(|declaration| declaration.start_byte() >= type_node.start_byte())
            {
                return None;
            }
        }
        // An out-of-line definition's logical owner is not its AST parent.
        // Resolving relative names across that boundary needs the resolver.
        if !global
            && (scope.kind() == "function_definition"
                && scoped_function_definition(scope).is_some()
                || scope
                    .child_by_field_name("name")
                    .is_some_and(|name| name.kind() == "qualified_identifier"))
        {
            return None;
        }
    }
    None
}

fn cpp_switch_pointer_depth(mut declarator: Node<'_>) -> Option<usize> {
    let mut depth = 0;
    loop {
        match declarator.kind() {
            "identifier" | "field_identifier" => return Some(depth),
            "pointer_declarator" => {
                depth += 1;
                declarator = declarator.child_by_field_name("declarator")?;
            }
            "init_declarator" => declarator = declarator.child_by_field_name("declarator")?,
            "reference_declarator" | "parenthesized_declarator" | "attributed_declarator" => {
                declarator = first_named_child(declarator)?
            }
            _ => return None,
        }
    }
}

fn cpp_switch_enum_type<'tree>(switch: Node<'tree>, source: &str) -> Option<Node<'tree>> {
    let mut operand = condition_expression(switch)?;
    let mut fields = Vec::new();
    while operand.kind() == "field_expression" {
        fields.push(operand);
        operand = operand.child_by_field_name("argument")?;
    }
    if operand.kind() != "identifier" {
        return None;
    }
    let mut declaration =
        cpp_switch_local_declaration(switch, node_text(operand, source)?, source)?;
    for field in fields.into_iter().rev() {
        let operator = field.child_by_field_name("operator")?;
        let expected_depth = match operator.kind() {
            "." => 0,
            "->" => 1,
            _ => return None,
        };
        if cpp_switch_pointer_depth(declaration.declarator)? != expected_depth {
            return None;
        }
        let record = cpp_switch_named_type(declaration.type_node, source)?;
        if !matches!(
            record.kind(),
            "class_specifier" | "struct_specifier" | "union_specifier"
        ) {
            return None;
        }
        let name = node_text(field.child_by_field_name("field")?, source)?;
        let mut member = None;
        for field_declaration in named_children_iter(record.child_by_field_name("body")?)
            .filter(|node| node.kind() == "field_declaration")
        {
            for declarator in field_declaration
                .children_by_field_name("declarator", &mut field_declaration.walk())
            {
                if declarator_name_node(declarator).and_then(|name| node_text(name, source))
                    == Some(name)
                {
                    member = Some(CppSwitchDeclaration {
                        type_node: field_declaration.child_by_field_name("type")?,
                        declarator,
                    });
                }
            }
        }
        declaration = member?;
    }
    if cpp_switch_pointer_depth(declaration.declarator)? != 0 {
        return None;
    }
    let enum_type = cpp_switch_named_type(declaration.type_node, source)?;
    (enum_type.kind() == "enum_specifier").then_some(enum_type)
}

fn declarator_identifier<'tree>(node: Node<'tree>) -> Option<Node<'tree>> {
    let mut current = node;
    loop {
        match current.kind() {
            "identifier" | "field_identifier" | "statement_identifier" => return Some(current),
            "init_declarator"
            | "pointer_declarator"
            | "reference_declarator"
            | "array_declarator"
            | "parenthesized_declarator"
            | "attributed_declarator" => {
                current = current.child_by_field_name("declarator")?;
            }
            "qualified_identifier" => current = current.child_by_field_name("name")?,
            _ => return None,
        }
    }
}

fn loop_variable<'tree>(loop_node: Node<'tree>, source: &'tree str) -> Option<&'tree str> {
    let declarator = if loop_node.kind() == "for_range_loop" {
        loop_node.child_by_field_name("declarator")
    } else {
        let initializer = loop_node.child_by_field_name("initializer")?;
        if initializer.kind() == "declaration" {
            initializer
                .child_by_field_name("declarator")
                .and_then(declarator_identifier)
        } else if initializer.kind() == "assignment_expression" {
            initializer
                .child_by_field_name("left")
                .and_then(expression_name_node)
        } else {
            None
        }
    }?;
    let name = declarator_identifier(declarator).or(Some(declarator))?;
    node_text(name, source)
}

impl brokk_bifrost_core::analyzer::statement_facts::producer::StatementFactSyntax
    for CppStructuralSpec
{
    fn supports_kind(
        &self,
        kind: brokk_bifrost_core::analyzer::statement_facts::StatementFactKind,
    ) -> bool {
        use brokk_bifrost_core::analyzer::statement_facts::StatementFactKind;
        !matches!(
            kind,
            StatementFactKind::NestedIfStatements | StatementFactKind::MisleadingIndentation
        )
    }

    fn roles<'tree>(&self, node: Node<'tree>, role: Role) -> Vec<Node<'tree>> {
        let target = match role {
            Role::Test if node.kind() == "case_statement" => node.child_by_field_name("value"),
            Role::Test => condition_expression(node),
            Role::Consequence => node.child_by_field_name("consequence"),
            Role::Alternative => {
                brokk_bifrost_core::analyzer::structural::body_relations::if_alternative_body(
                    node,
                    brokk_bifrost_core::analyzer::structural::body_relations::syntax_for(
                        Language::Cpp,
                    )
                    .expect("C++ body syntax"),
                )
            }
            Role::Body => node.child_by_field_name("body"),
            Role::Operator => node.child_by_field_name("operator"),
            Role::Left => node.child_by_field_name("left"),
            Role::Right => node.child_by_field_name("right"),
            Role::Label => node.child_by_field_name("label"),
            _ => None,
        };
        target.into_iter().collect()
    }

    fn is_code_child(&self, node: Node<'_>) -> bool {
        !node.is_extra() && !node.kind().starts_with("preproc_") && node.kind() != "comment"
    }

    fn loop_variable(&self, node: Node<'_>, source: &str) -> Option<String> {
        matches!(node.kind(), "for_statement" | "for_range_loop")
            .then(|| loop_variable(node, source).map(str::to_owned))
            .flatten()
    }

    fn is_counted_loop(&self, node: Node<'_>) -> bool {
        node.kind() == "for_statement"
    }

    fn loop_initializers<'tree>(&self, node: Node<'tree>) -> Vec<Node<'tree>> {
        node.child_by_field_name("initializer")
            .into_iter()
            .collect()
    }

    fn is_alloca(&self, node: Node<'_>, source: &str) -> bool {
        node.kind() == "call_expression"
            && node
                .child_by_field_name("function")
                .and_then(|function| node_text(function, source))
                .is_some_and(|name| {
                    matches!(name, "alloca" | "__builtin_alloca" | "_alloca" | "_malloca")
                })
    }

    fn switch_enum<'tree>(&self, node: Node<'tree>, source: &str) -> Option<Node<'tree>> {
        cpp_switch_enum_type(node, source)
    }

    fn enumeration(
        &self,
        node: Node<'_>,
        source: &str,
    ) -> Option<(
        brokk_bifrost_core::analyzer::statement_facts::EnumFact,
        Vec<brokk_bifrost_core::analyzer::statement_facts::EnumeratorFact>,
    )> {
        use brokk_bifrost_core::analyzer::statement_facts::{EnumFact, EnumeratorFact};
        if node.kind() != "enum_specifier" {
            return None;
        }
        let range = node_range(node);
        let name = node
            .child_by_field_name("name")
            .and_then(|name| node_text(name, source))
            .map(str::to_owned);
        let mut enumerators = Vec::new();
        let mut stack = vec![node];
        while let Some(current) = stack.pop() {
            if current != node && current.kind() == "enum_specifier" {
                continue;
            }
            if current.kind() == "enumerator"
                && let Some(name) = current.child_by_field_name("name")
                && let Some(name) = node_text(name, source)
            {
                enumerators.push(EnumeratorFact {
                    range: node_range(current),
                    enum_range: range,
                    name: name.to_owned(),
                });
            }
            stack.extend(named_children_iter(current).filter(|child| !child.is_extra()));
        }
        Some((EnumFact { range, name }, enumerators))
    }

    fn name<'tree>(&self, node: Node<'tree>) -> Option<Node<'tree>> {
        expression_name_node(node)
    }
}

/// The persisted C++ generator label and the query-time rows share one classifier.
pub fn statement_fact_kind(node: Node<'_>, source: &str) -> Option<StatementFactKind> {
    brokk_bifrost_core::analyzer::statement_facts::producer::StatementFacts::new(
        &CPP_STRUCTURAL_SPEC,
    )
    .expect("C++ statement syntax")
    .classify(node, source, &Default::default())
}

pub(crate) fn capture_statement_fact_rows(
    node: Node<'_>,
    source: &str,
    rows: &mut brokk_bifrost_core::analyzer::statement_facts::StatementFactRows,
) {
    brokk_bifrost_core::analyzer::statement_facts::producer::StatementFacts::new(
        &CPP_STRUCTURAL_SPEC,
    )
    .expect("C++ statement syntax")
    .capture(node, source, &Default::default(), rows);
}

#[cfg(test)]
fn alloca_is_in_unbounded_loop(node: Node<'_>, source: &str) -> bool {
    statement_fact_kind(node, source) == Some(StatementFactKind::AllocaInLoop)
}

#[cfg(test)]
fn enum_switch_is_missing_case(node: Node<'_>, source: &str) -> bool {
    let producer = brokk_bifrost_core::analyzer::statement_facts::producer::StatementFacts::new(
        &CPP_STRUCTURAL_SPEC,
    )
    .unwrap();
    let mut rows = brokk_bifrost_core::analyzer::statement_facts::StatementFactRows::default();
    producer.capture(node, source, &Default::default(), &mut rows);
    rows.switches.iter().any(|fact| fact.missing_enum_case)
}

/// Whether tree-sitter recovered `.field = value` as a declaration child pair:
/// an `ERROR` containing only the anonymous dot immediately followed by an
/// `init_declarator` whose declarator is a real identifier.
///
/// This is intentionally narrower than rejecting declarators below `ERROR` in
/// general: macro-decorated declarations and ordinary comma-separated initialized
/// declarations also use recovery nodes and remain real declarations.
pub fn is_recovered_designator_init_declarator(node: Node<'_>) -> bool {
    if node.kind() != "init_declarator" {
        return false;
    }
    let Some(identifier) = node.child_by_field_name("declarator") else {
        return false;
    };
    if identifier.kind() != "identifier" || identifier.is_missing() {
        return false;
    }
    let Some(previous) = node.prev_named_sibling() else {
        return false;
    };
    if previous.kind() != "ERROR"
        || previous.named_child_count() != 0
        || previous.child_count() != 1
        || previous.end_byte() != node.start_byte()
    {
        return false;
    }
    previous.child(0).is_some_and(|child| {
        child.kind() == "."
            && !child.is_named()
            && child.start_byte() == previous.start_byte()
            && child.end_byte() == previous.end_byte()
    })
}

use brokk_bifrost_core::analyzer::tree_walk::last_named_field_child;

/// The declared name of a `namespace_definition`.
///
/// `namespace a::b { }` spells a `nested_namespace_specifier` that nests to
/// the right, so the innermost specifier's last child is the terminal segment.
/// An anonymous namespace has no `name` field at all and stays unnamed.
fn namespace_name_node<'tree>(namespace: Node<'tree>) -> Option<Node<'tree>> {
    let mut current = namespace.child_by_field_name("name")?;
    while current.kind() == "nested_namespace_specifier" {
        current = current.named_child(current.named_child_count().checked_sub(1)?)?;
    }
    Some(current)
}

pub fn declarator_name_node<'tree>(declarator: Node<'tree>) -> Option<Node<'tree>> {
    let mut current = declarator;
    loop {
        match current.kind() {
            "identifier"
            | "field_identifier"
            | "namespace_identifier"
            | "type_identifier"
            | "destructor_name"
            | "operator_name"
            | "operator_cast"
            | "primitive_type" => return Some(current),
            "qualified_identifier" => current = last_named_field_child(current, "name")?,
            "dependent_name" => current = first_named_child(current)?,
            "template_function" | "template_method" | "template_type" => {
                current = current.child_by_field_name("name")?;
            }
            "function_declarator"
            | "pointer_declarator"
            | "pointer_type_declarator"
            | "macro_modifier_declarator"
            | "variadic_declarator"
            | "array_declarator"
            | "init_declarator" => current = current.child_by_field_name("declarator")?,
            "attributed_declarator" => current = first_named_child(current)?,
            "reference_declarator" | "parenthesized_declarator" => {
                current = first_named_child(current)?;
            }
            _ => return None,
        }
    }
}

/// Grammar steps for the shared call-callee spine. A value expression has no step.
pub fn callee_spine_step(kind: &str) -> Option<CalleeSpineStep> {
    use CalleeSpineStep::{Field, FieldOrOnlyChild, Name, OnlyChild};
    match kind {
        "identifier"
        | "field_identifier"
        | "type_identifier"
        | "operator_name"
        | "operator_cast"
        | "destructor_name"
        | "literal_operator_name"
        | "primitive_type" => Some(Name),
        "qualified_identifier"
        | "scoped_identifier"
        | "scoped_type_identifier"
        | "template_function"
        | "template_method"
        | "template_type" => Some(Field("name")),
        "dependent_name" => Some(OnlyChild),
        "field_expression" => Some(Field("field")),
        "pointer_expression" => Some(FieldOrOnlyChild("argument")),
        _ => None,
    }
}

fn expression_name_node<'tree>(expression: Node<'tree>) -> Option<Node<'tree>> {
    let mut current = expression;
    loop {
        match current.kind() {
            "identifier"
            | "field_identifier"
            | "namespace_identifier"
            | "type_identifier"
            | "destructor_name"
            | "operator_name"
            | "primitive_type"
            | "this" => return Some(current),
            "qualified_identifier" => current = last_named_field_child(current, "name")?,
            "dependent_name" => current = first_named_child(current)?,
            "template_function" | "template_method" | "template_type" => {
                current = current.child_by_field_name("name")?;
            }
            "field_expression" => current = current.child_by_field_name("field")?,
            "call_expression" => current = current.child_by_field_name("function")?,
            "new_expression" => current = current.child_by_field_name("type")?,
            "parenthesized_expression" => current = first_named_child(current)?,
            _ => return declarator_name_node(current),
        }
    }
}

fn attach_qualified_scope_receiver(sink: &mut RoleSink<'_>, function: Node<'_>) {
    if function.kind() != "qualified_identifier" {
        return;
    }
    if let Some(scope) = function.child_by_field_name("scope") {
        attach_role_with_derived_name(sink, Role::Receiver, scope, expression_name_node);
    }
}

fn qualified_declarator_node(mut node: Node<'_>) -> Option<Node<'_>> {
    loop {
        if node.kind() == "qualified_identifier" {
            return Some(node);
        }
        node = node
            .child_by_field_name("declarator")
            .or_else(|| node.child_by_field_name("name"))
            .or_else(|| first_named_child(node))?;
    }
}

fn scoped_function_definition(node: Node<'_>) -> Option<Node<'_>> {
    node.child_by_field_name("declarator")
        .and_then(qualified_declarator_node)
        .and_then(|qualified| qualified.child_by_field_name("scope"))
}

pub fn constructor_scope_matches_name(scope: Node<'_>, name: Node<'_>, source: &str) -> bool {
    node_text(scope, source) == node_text(name, source)
}

fn is_constructor_definition(node: Node<'_>, source: &str) -> bool {
    node.child_by_field_name("declarator")
        .and_then(qualified_declarator_node)
        .and_then(|qualified| {
            Some((
                expression_name_node(qualified.child_by_field_name("scope")?)?,
                expression_name_node(last_named_field_child(qualified, "name")?)?,
            ))
        })
        .is_some_and(|(scope, name)| constructor_scope_matches_name(scope, name, source))
}

fn unquoted_include_span(node: Node<'_>) -> Option<Span> {
    if !matches!(node.kind(), "string_literal" | "system_lib_string") {
        return None;
    }
    unquoted_string_content_span(node)
}

/// The names of every function-like macro this translation unit defines, read
/// from `preproc_function_def` name fields.
///
/// The walk is iterative and descends only through preprocessor conditional
/// blocks, which is where a definition can nest. A `#define` written inside a
/// function body is not collected; that is a known and stated boundary, not an
/// approximation of one.
fn function_like_macro_names(root: Node<'_>, source: &str) -> HashSet<String> {
    let mut names = HashSet::default();
    let mut stack = vec![root];
    while let Some(node) = stack.pop() {
        for child in named_children_iter(node) {
            match child.kind() {
                "preproc_function_def" => {
                    if let Some(name) = child.child_by_field_name("name") {
                        names.insert(source[name.start_byte()..name.end_byte()].to_owned());
                    }
                }
                "preproc_if" | "preproc_ifdef" | "preproc_else" | "preproc_elif"
                | "preproc_elifdef" => stack.push(child),
                _ => {}
            }
        }
    }
    names
}

/// Return the one identifier-bearing node that spells a member in a C++
/// `field_expression`.
///
/// The grammar permits the `field` child to be a qualified name, a dependent
/// name, a template method, or a destructor name. `expression_name_node`
/// already follows those wrappers to their terminal name. Walking upward from
/// the candidate and comparing that terminal node keeps receiver identifiers,
/// declaration names, field-designator labels, and path prefixes out of the
/// member role without looking at source text.
fn cpp_member_position(node: Node<'_>) -> Option<OccurrenceRole> {
    if !matches!(
        node.kind(),
        "identifier" | "field_identifier" | "type_identifier" | "operator_name" | "destructor_name"
    ) {
        return None;
    }

    let mut current = node;
    while let Some(parent) = current.parent() {
        if parent.kind() == "field_expression" {
            let field = parent.child_by_field_name("field")?;
            return expression_name_node(field)
                .filter(|name| name.id() == node.id())
                .map(|_| OccurrenceRole::MemberPosition);
        }

        // These are the only named wrappers that can occur between the
        // terminal field name and its owning field expression.
        if matches!(
            parent.kind(),
            "qualified_identifier" | "dependent_name" | "template_method" | "destructor_name"
        ) {
            current = parent;
        } else {
            return None;
        }
    }
    None
}

/// What declares a C or C++ binder.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
enum CppBinderOwner<'tree> {
    /// A parameter of a function definition, a lambda or a `catch` clause.
    Parameter,
    /// A local declaration; the node is the declarator the name completes.
    Local(Node<'tree>),
    /// A range-based `for` variable; the node is the loop.
    RangeFor(Node<'tree>),
    /// A structured binding; the node is the binding declarator.
    StructuredBinding(Node<'tree>),
    /// A lambda init-capture (`[x = y]`).
    InitCapture,
}

/// Declarator wrappers that carry a name inward through their `declarator`
/// field or their single named child.
const CPP_DECLARATOR_WRAPPERS: &[&str] = &[
    "pointer_declarator",
    "array_declarator",
    "reference_declarator",
    "parenthesized_declarator",
    "attributed_declarator",
    "variadic_declarator",
];

/// What declares `node` as a C or C++ variable, or `None` when it is not a
/// variable binder.
///
/// The name is found by walking up the declarator chain. A name that reaches
/// a function declarator without passing a pointer or reference declarator
/// names a function; one that does names a function pointer variable. A
/// parameter binds only in a function definition, a lambda or a `catch`
/// clause; a prototype's parameter names bind nothing. A file-scope or
/// member declaration names a member or a global, not a lexical binding.
fn cpp_binder_owner<'tree>(
    node: Node<'tree>,
    parent: impl Fn(Node<'tree>) -> Option<Node<'tree>>,
    mut field_name: impl FnMut(Node<'tree>, Node<'tree>) -> Option<&'static str>,
) -> Option<CppBinderOwner<'tree>> {
    if node.kind() != "identifier" {
        return None;
    }
    let mut child = node;
    let mut current = parent(node)?;
    let mut indirect = false;
    loop {
        // This field lookup scans earlier siblings. Generated C initializer
        // lists can be enormous, so only ask for fields on binder-shaped nodes.
        match current.kind() {
            kind if CPP_DECLARATOR_WRAPPERS.contains(&kind) => {
                let field = field_name(current, child);
                if field.is_some() && field != Some("declarator") {
                    return None;
                }
                indirect |= matches!(kind, "pointer_declarator" | "reference_declarator");
            }
            "function_declarator" => {
                let field = field_name(current, child);
                if field != Some("declarator") || !indirect {
                    return None;
                }
            }
            "init_declarator" => {
                let field = field_name(current, child);
                if field != Some("declarator") {
                    return None;
                }
            }
            "declaration" => {
                let field = field_name(current, child);
                if field != Some("declarator") {
                    return None;
                }
                let local = std::iter::successors(parent(current), |node| parent(*node))
                    .take_while(|node| {
                        !matches!(
                            node.kind(),
                            "translation_unit"
                                | "field_declaration_list"
                                | "declaration_list"
                                | "namespace_definition"
                        )
                    })
                    .any(|node| {
                        matches!(
                            node.kind(),
                            "compound_statement" | "for_statement" | "condition_clause"
                        )
                    });
                // The name's scope starts at the end of its declarator, before
                // any initializer.
                let declarator = if child.kind() == "init_declarator" {
                    child.child_by_field_name("declarator")?
                } else {
                    child
                };
                return local.then_some(CppBinderOwner::Local(declarator));
            }
            "parameter_declaration"
            | "optional_parameter_declaration"
            | "variadic_parameter_declaration" => {
                let field = field_name(current, child);
                if field != Some("declarator") {
                    return None;
                }
                let parameter_parent = parent(current)?;
                let list = if parameter_parent.kind() == "explicit_object_parameter_declaration" {
                    // The explicit-object wrapper owns exactly `this` and this
                    // parameter; only then may its parent supply the list.
                    if parameter_parent.named_child(0).map(|node| node.kind()) != Some("this")
                        || parameter_parent.named_child(1) != Some(current)
                    {
                        return None;
                    }
                    parent(parameter_parent)?
                } else {
                    parameter_parent
                };
                if list.kind() != "parameter_list" {
                    return None;
                }
                let owner = parent(list)?;
                let binds = match owner.kind() {
                    "catch_clause" => true,
                    "lambda_declarator" | "abstract_function_declarator" => parent(owner)
                        .is_some_and(|lambda| {
                            lambda.kind() == "lambda_expression"
                                && lambda.child_by_field_name("declarator") == Some(owner)
                        }),
                    "function_declarator" => {
                        let mut declarator = owner;
                        loop {
                            let Some(up) = parent(declarator) else {
                                break false;
                            };
                            if up.kind() == "function_definition" {
                                break field_name_in_parent(up, declarator) == Some("declarator");
                            }
                            if !CPP_DECLARATOR_WRAPPERS.contains(&up.kind()) {
                                break false;
                            }
                            declarator = up;
                        }
                    }
                    _ => false,
                };
                return binds.then_some(CppBinderOwner::Parameter);
            }
            "for_range_loop" => {
                let field = field_name(current, child);
                return (field == Some("declarator")).then_some(CppBinderOwner::RangeFor(current));
            }
            "structured_binding_declarator" => {
                return Some(CppBinderOwner::StructuredBinding(current));
            }
            "lambda_capture_initializer" => {
                let field = field_name(current, child);
                return (field == Some("left")).then_some(CppBinderOwner::InitCapture);
            }
            _ => return None,
        }
        child = current;
        current = parent(current)?;
    }
}

/// Whether `node` declares a C or C++ variable, climbing through the walk's
/// parent index: asking `Node::parent` re-descends from the root, which is
/// quadratic over a large file.
fn cpp_is_binder<'tree>(node: Node<'tree>, parents: &ParentIndex<'tree>) -> bool {
    cpp_binder_owner(node, |node| parents.parent(node), field_name_in_parent).is_some()
}

/// The binding one C or C++ binder token introduces, and the interval it is
/// in effect over.
///
/// A parameter or init-capture is in effect over its whole function, lambda
/// or catch clause. A local is in effect from the end of its declarator: C
/// and C++ start a name's scope there, before its initializer, so in
/// `int x = x;` the right side reads the new `x`. A condition declaration is
/// therefore in effect over the rest of its `if`, including `else`. A
/// range-`for` variable is in effect over the loop body, and a structured
/// binding from the end of its binding declarator.
fn cpp_binding_activation(binder: Node<'_>, scope: Range) -> Option<BindingActivation> {
    let binding = |kind, hoisting, activation| {
        Some(BindingActivation {
            kind,
            hoisting,
            activation,
        })
    };
    let after = |node: Node<'_>| Range {
        start_byte: node.end_byte(),
        end_byte: scope.end_byte,
        start_line: node.end_position().row + 1,
        end_line: scope.end_line,
    };
    match cpp_binder_owner(binder, |node| node.parent(), field_name_in_parent)? {
        CppBinderOwner::Parameter | CppBinderOwner::InitCapture => {
            binding(BindingKind::Parameter, HoistingClass::ScopeWide, scope)
        }
        CppBinderOwner::Local(declarator) => binding(
            BindingKind::Local,
            HoistingClass::SourceOrder,
            after(declarator),
        ),
        CppBinderOwner::RangeFor(loop_node) => binding(
            BindingKind::LoopVariable,
            HoistingClass::DeclaredHead,
            node_range(loop_node.child_by_field_name("body")?),
        ),
        CppBinderOwner::StructuredBinding(declarator) => binding(
            BindingKind::Local,
            HoistingClass::SourceOrder,
            after(declarator),
        ),
    }
}

impl StructuralSpec for CppStructuralSpec {
    fn language(&self) -> Language {
        Language::Cpp
    }

    fn supports_boolean_literal_value(&self) -> bool {
        true
    }

    fn supports_string_literal_value(&self) -> bool {
        true
    }

    fn string_literal_value_may_be_absent(&self, node: Node<'_>, source: &str) -> bool {
        matches!(node.kind(), "string_literal" | "raw_string_literal")
            && cpp_string_literal_value(node, source).is_none()
    }

    fn string_literal_value(&self, node: Node<'_>, source: &str) -> Option<String> {
        cpp_string_literal_value(node, source)
    }

    fn extra_emitted_kinds(&self) -> &'static [NormalizedKind] {
        // Refinement and embedded-leaf outputs beyond the grammar kind table.
        &[NormalizedKind::Constructor, NormalizedKind::Method]
    }

    fn kind_table(&self) -> &'static [(&'static str, NormalizedKind)] {
        CPP_KIND_TABLE
    }

    fn statement_fact_syntax(
        &self,
    ) -> Option<&dyn brokk_bifrost_core::analyzer::statement_facts::producer::StatementFactSyntax>
    {
        Some(self)
    }

    fn generator_construct(
        &self,
        node: Node<'_>,
        _kind: NormalizedKind,
        source: &str,
    ) -> Option<&'static str> {
        statement_fact_kind(node, source).map(StatementFactKind::construct)
    }

    fn refine_kind(
        &self,
        node: Node<'_>,
        kind: NormalizedKind,
        enclosing: Option<NormalizedKind>,
        source: &str,
        _context: &CallSiteContext,
    ) -> NormalizedKind {
        if kind == NormalizedKind::Function
            && (enclosing == Some(NormalizedKind::Class)
                || scoped_function_definition(node).is_some())
        {
            if is_constructor_definition(node, source) {
                NormalizedKind::Constructor
            } else {
                NormalizedKind::Method
            }
        } else {
            kind
        }
    }

    fn supports_kind(&self, kind: NormalizedKind) -> bool {
        matches!(
            kind,
            NormalizedKind::Method | NormalizedKind::Constructor | NormalizedKind::SyntaxError
        ) || self
            .kind_table()
            .iter()
            .any(|(_, fact_kind)| fact_kind.satisfies(kind))
    }

    fn supports_role(&self, role: Role) -> bool {
        !matches!(
            role,
            Role::Kwarg | Role::Decorator | Role::Iterable | Role::Element
        )
    }

    fn call_site_context(&self, root: Node<'_>, source: &str) -> CallSiteContext {
        CallSiteContext::with_macro_derived_callees(function_like_macro_names(root, source))
    }

    /// A `new_expression` is a constructor call, and a call whose callee names
    /// a function-like macro of this translation unit has an argument list
    /// that belongs to the macro, not to the callable that finally runs
    /// (#1478). `CALL_TWICE(2)` parses as an ordinary call of two source
    /// arguments even when the expansion calls a three-parameter callable, so
    /// the honest answer is unknown coverage and no argument rows at all —
    /// never a fabricated list an exact-arity assertion could read as clean.
    ///
    /// The boundary is deliberate: only macros defined in this file are
    /// known here, because that is what this file's parse tree contains. A
    /// macro defined in an included header leaves the site exact, which is
    /// the same answer the analyzer gives today.
    fn call_site_facts(
        &self,
        node: Node<'_>,
        source: &str,
        context: &CallSiteContext,
    ) -> Option<CallSiteFacts> {
        if node.kind() == "new_expression" {
            return Some(CallSiteFacts::of_kind(CallKind::Constructor));
        }
        let callee = node.child_by_field_name("function")?;
        (callee.kind() == "identifier"
            && context.is_macro_derived_callee(&source[callee.start_byte()..callee.end_byte()]))
        .then(|| CallSiteFacts::of_coverage(CallShapeCoverage::UnknownMacroDerived))
    }

    fn occurrence_role_support(&self) -> &OccurrenceRoleSupport {
        static SUPPORT: OccurrenceRoleSupport = OccurrenceRoleSupport::NONE
            .supported(OccurrenceRole::MemberPosition)
            .supported(OccurrenceRole::ValueReference)
            .supported(OccurrenceRole::Binder);
        &SUPPORT
    }

    fn lexical_environment_support(&self) -> &LexicalEnvironmentSupport {
        // C and C++ derive scopes and binding intervals; import binders and
        // the package clause are not derived. The call seams report
        // per-candidate callable applicability (#1478 M3).
        static SUPPORT: LexicalEnvironmentSupport = LexicalEnvironmentSupport::NONE
            .supported(EnvironmentAxis::Scopes)
            .supported(EnvironmentAxis::BindingIntervals)
            .supported(EnvironmentAxis::CallableApplicability);
        &SUPPORT
    }

    /// An `if` statement is a scope: a C++ condition or init-statement
    /// declaration is in effect in both branches and nowhere after.
    fn scope_formation(&self, kind: NormalizedKind) -> ScopeFormation {
        if matches!(kind, NormalizedKind::If | NormalizedKind::Switch) {
            ScopeFormation::BindingScope
        } else {
            default_scope_formation(kind)
        }
    }

    fn binding_activation(&self, binder: Node<'_>, scope: Range) -> Option<BindingActivation> {
        cpp_binding_activation(binder, scope)
    }

    fn materialization_support(&self) -> &DeclarationMaterializationSupport {
        &CPP_MATERIALIZATION_SUPPORT
    }

    fn reference_edge_support(&self) -> &ReferenceEdgeSupport {
        &INVERSE_REFERENCE_EDGE_SUPPORT
    }

    fn identity_route_support(&self) -> &IdentityRouteSupport {
        // C++'s occurrence adapter is shallow, so it claims no path axes. Its
        // declaration layer keeps prototype/body occurrences distinct, which
        // the physical-grouping axis carries, and the analyzer now labels each
        // of those occurrences a head or a body and pairs a prototype with the
        // out-of-line callable body that defines it, so the
        // declaration-definition peer relation is supplied as typed rows with
        // the body occurrence's own range as provenance (#1650). Classes stay
        // outside that relation: a same-file forward declaration is not a
        // distinct occurrence, and across files a class carries no linkage
        // evidence to pair on.
        static SUPPORT: IdentityRouteSupport = IdentityRouteSupport::NONE
            .supported_axis(IdentityAxis::CanonicalIdentity)
            .supported_axis(IdentityAxis::PhysicalGrouping)
            .supported_relation(RouteHopKind::NestedOwner)
            .supported_relation(RouteHopKind::DeclarationDefinitionPeer);
        &SUPPORT
    }

    fn extract(&self, node: Node<'_>, kind: NormalizedKind, sink: &mut RoleSink<'_>) {
        if let Some(role) = cpp_member_position(node) {
            sink.occurrence_role(node, role);
        } else if cpp_is_binder(node, sink.parents()) {
            sink.occurrence_role(node, OccurrenceRole::Binder);
        }

        match kind {
            NormalizedKind::Call => {
                let function_field = if node.kind() == "new_expression" {
                    "type"
                } else {
                    "function"
                };
                if let Some(function) = node.child_by_field_name(function_field) {
                    attach_terminal_callee(
                        sink,
                        function,
                        terminal_callee_leaf(function, callee_spine_step),
                    );
                    // The callee token of a free-function call is a plain value
                    // read, and it is the only occurrence the call site leaves
                    // behind when the function is not indexed (#3466). Member
                    // calls are excluded: their terminal field is already the
                    // member-position occurrence, and classifying it twice would
                    // report one call site as two. A composite callee
                    // expression names its own callee at an inner node
                    // (`f()()`), so it is excluded too.
                    if node.kind() == "call_expression"
                        && !matches!(function.kind(), "field_expression" | "call_expression")
                        && let Some(callee) = expression_name_node(function)
                        && self.kind_table().iter().any(|(node_kind, kind)| {
                            *node_kind == callee.kind() && self.should_extract(callee, *kind)
                        })
                    {
                        sink.occurrence_role(callee, OccurrenceRole::ValueReference);
                    }
                    if function.kind() == "field_expression"
                        && let Some(argument) = function.child_by_field_name("argument")
                    {
                        attach_role_with_derived_name(
                            sink,
                            Role::Receiver,
                            argument,
                            expression_name_node,
                        );
                    }
                    attach_qualified_scope_receiver(sink, function);
                }
                if let Some(arguments) = node.child_by_field_name("arguments") {
                    attach_positional_argument_roles(sink, arguments, expression_name_node);
                }
            }
            NormalizedKind::FieldAccess => {
                if let Some(field) = node.child_by_field_name("field") {
                    attach_role_with_derived_name(sink, Role::Field, field, expression_name_node);
                    if let Some(name) = expression_name_node(field) {
                        sink.set_name(name);
                    }
                }
                if let Some(argument) = node.child_by_field_name("argument") {
                    attach_role_with_derived_name(
                        sink,
                        Role::Object,
                        argument,
                        expression_name_node,
                    );
                }
            }
            NormalizedKind::Function | NormalizedKind::Method | NormalizedKind::Constructor => {
                if let Some(name) = node
                    .child_by_field_name("declarator")
                    .and_then(declarator_name_node)
                {
                    sink.set_name(name);
                }
            }
            NormalizedKind::Module => {
                if let Some(name) = namespace_name_node(node) {
                    sink.set_name(name);
                }
            }
            NormalizedKind::Class | NormalizedKind::Declaration => {
                if let Some(name) = node
                    .child_by_field_name("name")
                    .and_then(declarator_name_node)
                    .or_else(|| node.child_by_field_name("name"))
                {
                    sink.set_name(name);
                }
            }
            NormalizedKind::Assignment => match node.kind() {
                "init_declarator" => {
                    if let Some(declarator) = node.child_by_field_name("declarator") {
                        attach_role_with_derived_name(
                            sink,
                            Role::Left,
                            declarator,
                            declarator_name_node,
                        );
                        if let Some(name) = declarator_name_node(declarator) {
                            sink.set_name(name);
                        }
                    }
                    if let Some(value) = node.child_by_field_name("value") {
                        attach_role_with_derived_name(
                            sink,
                            Role::Right,
                            value,
                            expression_name_node,
                        );
                    }
                }
                "assignment_expression" => {
                    if let Some(left) = node.child_by_field_name("left") {
                        attach_role_with_derived_name(sink, Role::Left, left, expression_name_node);
                    }
                    if let Some(right) = node.child_by_field_name("right") {
                        attach_role_with_derived_name(
                            sink,
                            Role::Right,
                            right,
                            expression_name_node,
                        );
                    }
                }
                _ => {}
            },
            NormalizedKind::Import => {
                if let Some(path) = node.child_by_field_name("path") {
                    if let Some(name) = unquoted_include_span(path) {
                        sink.role_named_span(Role::Module, path, name);
                    } else {
                        attach_role_with_derived_name(
                            sink,
                            Role::Module,
                            path,
                            expression_name_node,
                        );
                    }
                }
            }
            NormalizedKind::Identifier => match expression_name_node(node) {
                Some(name) => sink.set_name(name),
                None => sink.set_name(node),
            },
            _ => {}
        }
    }
}

#[cfg(test)]
mod tests {
    use super::CPP_STRUCTURAL_SPEC;
    use super::cpp_binder_owner;
    use super::cpp_member_position;
    use super::field_name_in_parent;
    use super::node_range;
    use brokk_bifrost_core::analyzer::source_facts::PrimarySourceFactCollector;
    use brokk_bifrost_core::analyzer::structural::collector::StructuralFactCollector;
    use brokk_bifrost_core::analyzer::structural::facts::StructuralFactRows;
    use brokk_bifrost_core::analyzer::structural::kinds::NormalizedKind;
    use brokk_bifrost_core::analyzer::structural::occurrences::OccurrenceRole;
    use brokk_bifrost_core::analyzer::structural::resolution::BindingKind;
    use brokk_bifrost_core::analyzer::structural::spec::{CompiledKinds, RoleSink, StructuralSpec};
    use brokk_bifrost_core::analyzer::tree_walk::ParentIndex;
    use brokk_bifrost_core::hash::HashMap;
    use brokk_bifrost_test_macros::hardwon;
    use tree_sitter::Parser;

    #[test]
    #[hardwon(
        "e3c20990a105: quicksilver round 4 on brokk-bifrost-cpp: unrelated comparisons suppress alloca-in-loop"
    )]
    fn alloca_bound_must_constrain_loop_variable() {
        for (condition, expected) in [
            ("i < n && enabled < 1", true),
            ("i < n || i < 1", true),
            ("i < 1", false),
            ("1 > i && enabled", false),
        ] {
            let source = format!(
                "void f(int n, int enabled) {{ for (int i=0; {condition}; ++i) {{ alloca(16); }} }}"
            );
            let mut parser = Parser::new();
            parser
                .set_language(&tree_sitter_cpp::LANGUAGE.into())
                .unwrap();
            let tree = parser.parse(&source, None).unwrap();
            let mut stack = vec![tree.root_node()];
            let mut actual = None;
            while let Some(node) = stack.pop() {
                if node.kind() == "call_expression" {
                    actual = Some(super::alloca_is_in_unbounded_loop(node, &source));
                }
                stack.extend(super::named_children_iter(node));
            }
            assert_eq!(actual, Some(expected), "{source}");
        }
    }

    #[test]
    #[hardwon(
        "e3c20990a105: quicksilver round 4 on brokk-bifrost-cpp: integer switches borrow unrelated enum cases"
    )]
    fn integer_switch_is_not_an_enum_switch() {
        let source = "enum E { A, B }; void f(int value) { switch(value) { case A: break; } }";
        let mut parser = Parser::new();
        parser
            .set_language(&tree_sitter_cpp::LANGUAGE.into())
            .unwrap();
        let tree = parser.parse(source, None).unwrap();
        let mut stack = vec![tree.root_node()];
        let mut checked = false;
        while let Some(node) = stack.pop() {
            if node.kind() == "switch_statement" {
                checked = true;
                assert!(!super::enum_switch_is_missing_case(node, source));
            }
            stack.extend(super::named_children_iter(node));
        }
        assert!(checked);
    }

    #[test]
    #[hardwon(
        "e3c20990a105: quicksilver round 4 on brokk-bifrost-cpp: enum coverage needs scoped local declaration evidence"
    )]
    fn enum_switch_uses_local_type_evidence() {
        for (source, expected) in [
            (
                "enum E { A,B }; void f(E e) { switch(e) {case A:break;} }",
                vec![true],
            ),
            (
                "enum E { A,B }; void f() { E e=A; switch(e) {case A:break;} }",
                vec![true],
            ),
            (
                "enum class E { A,B }; void f(E e) { switch(e) {case E::A:break;} }",
                vec![true],
            ),
            (
                "namespace ns { enum class E { A,B }; } void f(ns::E e) { switch(e) {case ns::E::A:break;} }",
                vec![true],
            ),
            (
                "enum E { A,B }; struct S { E state; }; void f(S s) { switch(s.state) {case A:break;} }",
                vec![true],
            ),
            (
                "enum E { A,B }; struct S { E state; }; void f() { S s; switch(s.state) {case A:break;} }",
                vec![true],
            ),
            (
                "enum E { A,B }; void f(E e) { { int e=0; switch(e) {case A:break;} } switch(e) {case A:break;} }",
                vec![false, true],
            ),
            (
                "enum E { A,B }; void f(E e) { { int e=0; } switch(e) {case A:break;} }",
                vec![true],
            ),
            (
                "enum E { A,B }; void f() { switch(e) {case A:break;} E e=A; }",
                vec![false],
            ),
            (
                "enum E { A,B }; using Alias=E; void f(Alias e) { switch(e) {case A:break;} }",
                vec![false],
            ),
            (
                "enum E { A,B }; void f(E e) { switch(e==A) {case A:break;} }",
                vec![false],
            ),
            (
                "enum E { A,B }; E e; void f() { switch(e) {case A:break;} }",
                vec![false],
            ),
            (
                "enum E { A,B }; void f(E &e) { switch(e) {case A:break;} }",
                vec![true],
            ),
            (
                "enum E { A,B }; void f(E *e) { switch(e) {case A:break;} }",
                vec![false],
            ),
            (
                "enum E { A,B }; struct S { E state; }; void f(S *s) { switch(s->state) {case A:break;} }",
                vec![true],
            ),
            (
                "enum E { A,B }; struct S { int state; }; void f(S s) { switch(s.state) {case A:break;} }",
                vec![false],
            ),
            (
                "enum E { A,B }; struct Inner { E state; }; struct Outer { Inner inner; }; void f(Outer s) { switch(s.inner.state) {case A:break;} }",
                vec![true],
            ),
            (
                "void f() { enum class E { A,B }; E e=E::A; switch(e) {case E::A:break;} }",
                vec![true],
            ),
            (
                "struct S { enum class E { A,B }; E state; }; void f(S s) { switch(s.state) {case S::E::A:break;} }",
                vec![true],
            ),
            (
                "namespace n { namespace m { enum class E { A,B }; } } void f(n::m::E e) { switch(e) {case n::m::E::A:break;} }",
                vec![true],
            ),
            (
                "enum E { A,B }; void f() { using E=int; E e=0; switch(e) {case A:break;} }",
                vec![false],
            ),
            (
                "enum E { A,B }; void f(E e) { { int e(); switch(e) {case A:break;} } }",
                vec![false],
            ),
            (
                "enum E { A,B }; void f(E e) { auto g=[e]() { switch(e) {case A:break;} }; }",
                vec![false],
            ),
            (
                "enum E { A,B }; void f() { auto g=[](E e) { switch(e) {case A:break;} }; }",
                vec![true],
            ),
            (
                "namespace n::m { enum class E { A,B }; } void f(n::m::E e) { switch(e) {case n::m::E::A:break;} }",
                vec![true],
            ),
            (
                "void f() { enum E { A,B } e=A; switch(e) {case A:break;} }",
                vec![true],
            ),
            (
                "enum E { A,B }; void f(E (&values)[2]) { for (E e : values) { switch(e) {case A:break;} } }",
                vec![true],
            ),
            (
                "enum E { A,B }; namespace n { enum E { A,C }; } void f() { using n::E; E e; switch(e) {case A:break;} }",
                vec![false],
            ),
            (
                "enum E { A,B }; namespace n { enum E { A }; void f(E); } void n::f(E e) { switch(e) {case n::A:break;} }",
                vec![false],
            ),
            (
                "enum E { A,B }; void f(E e) { switch(int e=0; e) {case A:break;} }",
                vec![false],
            ),
            (
                "enum E { A,B }; void f() { switch(E e=A; e) {case A:break;} }",
                vec![true],
            ),
            (
                "enum E { A,B }; template<typename E> void f(E e) { switch(e) {case A:break;} }",
                vec![false],
            ),
            (
                "enum E { A,B }; template<typename... T> void f(T... e) { switch(e) {case A:break;} }",
                vec![false],
            ),
            (
                "namespace n { enum E { A,B }; } namespace m { enum E { A }; } namespace r { namespace n=m; void f(n::E e) { switch(e) {case m::A:break;} } }",
                vec![false],
            ),
            (
                "struct R { enum E { A,B }; }; struct S { enum E { A }; }; void f() { using R=S; R::E e; switch(e) {case S::A:break;} }",
                vec![false],
            ),
            (
                "enum E { A,B }; struct Base { enum E { A }; }; struct S: Base { void f(E e) { switch(e) {case A:break;} } };",
                vec![false],
            ),
            (
                "enum E { A,B }; struct S { void f() { E e; switch(e) {case A:break;} } enum E { A }; };",
                vec![false],
            ),
        ] {
            let mut parser = Parser::new();
            parser
                .set_language(&tree_sitter_cpp::LANGUAGE.into())
                .unwrap();
            let tree = parser.parse(source, None).unwrap();
            assert!(
                !tree.root_node().has_error(),
                "{source}: {}",
                tree.root_node().to_sexp()
            );
            let mut stack = vec![tree.root_node()];
            let mut results = Vec::new();
            while let Some(node) = stack.pop() {
                if node.kind() == "switch_statement" {
                    results.push((
                        node.start_byte(),
                        super::enum_switch_is_missing_case(node, source),
                    ));
                }
                stack.extend(super::named_children_iter(node));
            }
            results.sort_unstable_by_key(|(start, _)| *start);
            assert_eq!(
                results.into_iter().map(|(_, v)| v).collect::<Vec<_>>(),
                expected,
                "{source}"
            );
        }
    }

    fn collect_cpp_structural_facts(source: &str) {
        collect_structural_rows(source);
    }

    fn collect_structural_rows(source: &str) -> StructuralFactRows {
        let mut parser = Parser::new();
        parser
            .set_language(&tree_sitter_cpp::LANGUAGE.into())
            .expect("C++ grammar");
        let tree = parser.parse(source, None).expect("C++ parse");
        let root = tree.root_node();
        let context = super::CPP_STRUCTURAL_SPEC.call_site_context(root, source);
        let compiled = CompiledKinds::compile(
            &tree_sitter_cpp::LANGUAGE.into(),
            super::CPP_STRUCTURAL_SPEC.kind_table(),
        );
        let mut structural = StructuralFactCollector::new(
            &super::CPP_STRUCTURAL_SPEC,
            source,
            &context,
            ParentIndex::new(root),
            usize::MAX,
            None,
        );
        let mut source_facts = PrimarySourceFactCollector::new(source);
        let mut pending = vec![(root, None)];
        while let Some((node, parent)) = pending.pop() {
            let mut child_parent = parent;
            if node.is_named()
                && let Some(raw_kind) = compiled.kind_of(&node)
                && super::CPP_STRUCTURAL_SPEC.should_extract(node, raw_kind)
            {
                let kind = super::CPP_STRUCTURAL_SPEC.refine_kind(
                    node,
                    raw_kind,
                    parent.map(|id| structural.normalized_kind(id)),
                    source,
                    &context,
                );
                let id = structural
                    .enter(node, kind, parent, &mut source_facts)
                    .expect("unbounded C++ structural collector");
                let mut sink = structural.role_sink(&mut source_facts);
                super::CPP_STRUCTURAL_SPEC.extract(node, kind, &mut sink);
                structural
                    .accept_roles(id, sink.into_parts())
                    .expect("unbounded C++ structural roles");
                child_parent = Some(id);
            }
            for index in (0..node.named_child_count()).rev() {
                if let Some(child) = node.named_child(index) {
                    pending.push((child, child_parent));
                }
            }
        }
        structural
            .finish(root)
            .expect("C++ structural collection finishes")
    }

    fn member_occurrences(source: &str) -> Vec<(usize, &str, OccurrenceRole)> {
        let mut parser = Parser::new();
        parser
            .set_language(&tree_sitter_cpp::LANGUAGE.into())
            .expect("C++ grammar");
        let tree = parser.parse(source, None).expect("C++ parse");
        assert!(
            !tree.root_node().has_error(),
            "{}",
            tree.root_node().to_sexp()
        );
        let mut found = Vec::new();
        let mut pending = vec![tree.root_node()];
        while let Some(node) = pending.pop() {
            if let Some(role) = cpp_member_position(node) {
                found.push((
                    node.start_byte(),
                    &source[node.start_byte()..node.end_byte()],
                    role,
                ));
            }
            for index in (0..node.named_child_count()).rev() {
                if let Some(child) = node.named_child(index) {
                    pending.push(child);
                }
            }
        }
        found
    }

    #[test]
    #[hardwon("#4505: generated C initializer identifiers triggered repeated sibling scans")]
    fn binder_classification_scans_large_initializer_lists_linearly() {
        use std::fmt::Write as _;

        let mut source = String::from("int values[] = {");
        for index in 0..4096 {
            write!(source, "item_{index},").expect("append generated initializer item");
        }
        source.push_str("};\n");

        let mut parser = Parser::new();
        parser
            .set_language(&tree_sitter_cpp::LANGUAGE.into())
            .expect("C++ grammar");
        let tree = parser.parse(&source, None).expect("C++ parse");
        assert!(
            !tree.root_node().has_error(),
            "{}",
            tree.root_node().to_sexp()
        );
        let parents = ParentIndex::new(tree.root_node());
        let mut pending = vec![tree.root_node()];
        let mut identifiers = 0usize;
        let mut sibling_steps = 0usize;
        while let Some(node) = pending.pop() {
            if node.kind() == "identifier" {
                identifiers += 1;
                let _ = cpp_binder_owner(
                    node,
                    |node| parents.parent(node),
                    |parent, child| {
                        let mut cursor = parent.walk();
                        if !cursor.goto_first_child() {
                            return None;
                        }
                        loop {
                            sibling_steps += 1;
                            if cursor.node() == child {
                                return cursor.field_name();
                            }
                            if !cursor.goto_next_sibling() {
                                return None;
                            }
                        }
                    },
                );
            }
            let mut cursor = node.walk();
            let children = node.children(&mut cursor).collect::<Vec<_>>();
            pending.extend(children.into_iter().rev());
        }

        assert!(
            identifiers >= 4096,
            "parsed {identifiers} initializer identifiers"
        );
        assert!(
            sibling_steps <= identifiers * 4,
            "binder field lookup walked {sibling_steps} siblings for {identifiers} identifiers"
        );
    }

    #[test]
    #[brokk_bifrost_test_macros::hardwon(
        "#4407: ABI 15 lambda declarators lost parameter binder identity"
    )]
    fn lambda_parameters_are_binders_without_leaking_into_callable_bodies() {
        let source = concat!(
            "int enclosing(int outer) {\n",
            "    return [outer](int lambda) {\n",
            "        return [lambda](int nested) {\n",
            "            return outer + lambda + nested;\n",
            "        }(lambda);\n",
            "    }(outer);\n",
            "}\n",
        );
        let mut parser = Parser::new();
        parser
            .set_language(&tree_sitter_cpp::LANGUAGE.into())
            .expect("C++ grammar");
        let tree = parser.parse(source, None).expect("C++ parse");
        assert!(
            !tree.root_node().has_error(),
            "{}",
            tree.root_node().to_sexp()
        );

        let identifier_at = |start_byte| {
            let mut pending = vec![tree.root_node()];
            while let Some(node) = pending.pop() {
                if node.kind() == "identifier" && node.start_byte() == start_byte {
                    return Some(node);
                }
                for index in (0..node.named_child_count()).rev() {
                    if let Some(child) = node.named_child(index) {
                        pending.push(child);
                    }
                }
            }
            None
        };
        let outer_parameter =
            identifier_at(source.find("int outer").expect("outer parameter") + "int ".len())
                .expect("outer parameter");
        let lambda_parameter =
            identifier_at(source.find("int lambda").expect("lambda parameter") + "int ".len())
                .expect("lambda parameter");
        let nested_parameter =
            identifier_at(source.find("int nested").expect("nested parameter") + "int ".len())
                .expect("nested parameter");

        for parameter in [outer_parameter, lambda_parameter, nested_parameter] {
            assert_eq!(
                cpp_binder_owner(parameter, |node| node.parent(), field_name_in_parent),
                Some(super::CppBinderOwner::Parameter)
            );
            assert_eq!(
                super::cpp_binding_activation(parameter, node_range(tree.root_node()))
                    .map(|activation| activation.kind),
                Some(BindingKind::Parameter)
            );
        }

        for (start, name) in [
            (
                source
                    .find("return outer + lambda")
                    .expect("outer reference")
                    + "return ".len(),
                "outer",
            ),
            (
                source
                    .find("outer + lambda + nested")
                    .expect("lambda reference")
                    + "outer + ".len(),
                "lambda",
            ),
            (
                source.find("lambda + nested;").expect("nested reference") + "lambda + ".len(),
                "nested",
            ),
        ] {
            let reference = identifier_at(start).expect("body reference identifier");
            assert_eq!(
                cpp_binder_owner(reference, |node| node.parent(), field_name_in_parent),
                None,
                "body reference {name:?} was classified as a binder"
            );
        }
    }

    #[test]
    #[brokk_bifrost_test_macros::hardwon(
        "#4407: ABI 15 explicit-object receivers lost parameter binder identity"
    )]
    fn cpp_explicit_object_parameter_is_a_parameter_binder_without_body_leak() {
        let source = concat!(
            "struct Visitor {\n",
            "    int visit(this Visitor const& self, int ordinary) {\n",
            "        return self.value + ordinary;\n",
            "    }\n",
            "};\n",
            "using Callback = void (*)(int nested);\n",
        );
        let mut parser = Parser::new();
        parser
            .set_language(&tree_sitter_cpp::LANGUAGE.into())
            .expect("C++ grammar");
        let tree = parser.parse(source, None).expect("C++ parse");
        assert!(
            !tree.root_node().has_error(),
            "{}",
            tree.root_node().to_sexp()
        );

        let identifier_at = |start: usize, len: usize| {
            tree.root_node()
                .descendant_for_byte_range(start, start + len)
                .filter(|node| node.kind() == "identifier")
                .expect("identifier at source span")
        };
        let receiver = identifier_at(source.find("self,").expect("receiver binder"), 4);
        let receiver_body = identifier_at(
            source.find("return self").expect("receiver body reference") + "return ".len(),
            4,
        );
        let function_type_parameter =
            identifier_at(source.find("nested").expect("function type"), 6);
        let parents = ParentIndex::new(tree.root_node());

        assert_eq!(receiver.kind(), "identifier");
        assert_eq!(
            cpp_binder_owner(receiver, |node| node.parent(), field_name_in_parent),
            Some(super::CppBinderOwner::Parameter)
        );
        assert!(super::cpp_is_binder(receiver, &parents));
        assert_eq!(
            super::cpp_binding_activation(receiver, node_range(tree.root_node()))
                .map(|activation| activation.kind),
            Some(BindingKind::Parameter)
        );
        assert_eq!(
            cpp_binder_owner(receiver_body, |node| node.parent(), field_name_in_parent),
            None,
            "the receiver read in the body is not another binder"
        );
        assert!(!super::cpp_is_binder(receiver_body, &parents));
        assert_eq!(
            cpp_binder_owner(
                function_type_parameter,
                |node| node.parent(),
                field_name_in_parent
            ),
            None,
            "a function-type parameter remains outside callable binding ownership"
        );
    }

    #[test]
    fn attributed_declarator_resolves_its_declared_name() {
        let source = "int x [[maybe_unused]]; struct Widget { operator bool() const; };";
        let mut parser = Parser::new();
        parser
            .set_language(&tree_sitter_cpp::LANGUAGE.into())
            .expect("C++ grammar");
        let tree = parser.parse(source, None).expect("C++ parse");
        assert!(
            !tree.root_node().has_error(),
            "{}",
            tree.root_node().to_sexp()
        );

        let mut pending = vec![tree.root_node()];
        let mut attributed = None;
        let mut conversion = None;
        while let Some(node) = pending.pop() {
            match node.kind() {
                "attributed_declarator" => attributed = Some(node),
                "operator_cast" => conversion = Some(node),
                _ => {}
            }
            for index in (0..node.named_child_count()).rev() {
                if let Some(child) = node.named_child(index) {
                    pending.push(child);
                }
            }
        }
        let attributed = attributed.expect("attributed declarator");
        let name = super::declarator_name_node(attributed).expect("declarator name");

        assert_eq!(&source[name.byte_range()], "x");
        let conversion = conversion.expect("conversion operator");
        assert_eq!(
            super::declarator_name_node(conversion).map(|node| node.kind()),
            Some("operator_cast")
        );
    }

    #[test]
    fn cpp_member_position_is_limited_to_member_access_and_calls() {
        let source = concat!(
            "struct Widget {\n",
            "    int value;\n",
            "    int method(int label) {\n",
            "        return this->value + label.value + label.method()\n",
            "            + label.template convert<int>() + label.ns::member;\n",
            "    }\n",
            "};\n",
            "int build(Widget widget) {\n",
            "    Widget result{.value = widget.value};\n",
            "    return widget.method(result.value);\n",
            "}\n",
        );
        let found = member_occurrences(source);
        let member_texts = found
            .iter()
            .map(|(_, text, role)| (*text, *role))
            .collect::<Vec<_>>();

        assert_eq!(
            member_texts,
            vec![
                ("value", OccurrenceRole::MemberPosition),
                ("value", OccurrenceRole::MemberPosition),
                ("method", OccurrenceRole::MemberPosition),
                ("convert", OccurrenceRole::MemberPosition),
                ("member", OccurrenceRole::MemberPosition),
                ("value", OccurrenceRole::MemberPosition),
                ("method", OccurrenceRole::MemberPosition),
                ("value", OccurrenceRole::MemberPosition),
            ]
        );

        let at = |needle: &str| source.find(needle).expect("fixture token");
        for receiver in ["this->", "label.value", "widget.value", "result.value"] {
            let receiver_start = at(receiver);
            assert!(
                found.iter().all(|(offset, _, _)| *offset != receiver_start),
                "receiver was classified: {receiver:?}"
            );
        }
        let non_members = [
            at("Widget {"),
            at("int value") + "int ".len(),
            at("int method") + "int ".len(),
            at(".value =") + 1,
        ];
        for unrelated_start in non_members {
            assert!(
                found
                    .iter()
                    .all(|(offset, _, _)| *offset != unrelated_start),
                "non-member identifier at byte {unrelated_start} was classified"
            );
        }
    }

    #[test]
    #[brokk_bifrost_test_macros::hardwon(
        "#3466: C and C++ free-function calls published no resolver occurrence"
    )]
    fn cpp_occurrence_support_declares_member_position_and_free_callees() {
        let support = super::CPP_STRUCTURAL_SPEC.occurrence_role_support();
        assert!(support.is_supported(OccurrenceRole::MemberPosition));
        assert!(support.is_supported(OccurrenceRole::ValueReference));
        for role in [
            OccurrenceRole::ReceiverPosition,
            OccurrenceRole::LabelOrKey,
            OccurrenceRole::DeclarationName,
        ] {
            assert!(
                !support.is_supported(role),
                "unexpected C++ support for {role:?}"
            );
        }
    }

    #[test]
    fn cpp_string_literals_publish_decoded_values() {
        let source = r#"
const char *ordinary = "http://example.test/a\n";
const char *raw = R"(https://example.test/path)";
const char *wide = L"wide";
const char character = 'x';
const char *mixed = R"(\u0041)" "\u0042";
"#;
        let rows = collect_structural_rows(source);
        let values = rows
            .nodes()
            .iter()
            .filter(|node| node.kind == NormalizedKind::StringLiteral)
            .map(|node| node.string_value.clone())
            .collect::<Vec<_>>();

        assert_eq!(
            values,
            vec![
                Some("http://example.test/a\n".to_owned()),
                Some("https://example.test/path".to_owned()),
                None,
                None,
                Some(r"\u0041".to_owned()),
                Some("B".to_owned()),
            ]
        );
    }

    #[test]
    fn cpp_numeric_string_escapes_follow_scalar_and_ascii_boundaries() {
        // The grammar selects escape_sequence nodes; Unicode scalar validity
        // and the portable ASCII byte policy independently decide their values.
        let mut cases = vec![
            (
                r"\101\x42\u0043\U00000044".to_owned(),
                Some("ABCD".to_owned()),
            ),
            (r"\177".to_owned(), Some("\u{7f}".to_owned())),
            (r"\200".to_owned(), None),
            (r"\377".to_owned(), None),
            (r"\x7f".to_owned(), Some("\u{7f}".to_owned())),
            (r"\x80".to_owned(), None),
            (r"\x0041".to_owned(), Some("A".to_owned())),
            (r"\x007f".to_owned(), Some("\u{7f}".to_owned())),
            (r"\x0080".to_owned(), None),
            (r"\xfffffffff".to_owned(), None),
        ];
        for scalar in [
            0,
            0x7f,
            0x80,
            0xd7ff,
            0xd800,
            0xdfff,
            0xe000,
            0x10ffff,
            0x110000,
            u32::MAX,
        ] {
            let expected = char::from_u32(scalar).map(|character| character.to_string());
            cases.push((format!("\\U{scalar:08x}"), expected.clone()));
            if scalar <= 0xffff {
                cases.push((format!("\\u{scalar:04x}"), expected));
            }
        }
        for (escape, expected) in cases {
            let source = format!("const char *value = \"{escape}\";");
            let mut parser = Parser::new();
            parser
                .set_language(&tree_sitter_cpp::LANGUAGE.into())
                .unwrap();
            let tree = parser.parse(&source, None).unwrap();
            assert!(!tree.root_node().has_error(), "{source}");
            let mut stack = vec![tree.root_node()];
            let mut escapes = Vec::new();
            while let Some(node) = stack.pop() {
                if node.kind() == "escape_sequence" {
                    escapes.push(node.byte_range());
                }
                stack.extend(node.named_children(&mut node.walk()));
            }
            assert!(!escapes.is_empty(), "grammar did not select {source}");
            if escape.starts_with(r"\x00") {
                let expected_span = 21..21 + escape.len();
                assert_eq!(
                    escapes.as_slice(),
                    std::slice::from_ref(&expected_span),
                    "{source}"
                );
            }
            let rows = collect_structural_rows(&source);
            let values: Vec<_> = rows
                .nodes()
                .iter()
                .filter(|node| node.kind == NormalizedKind::StringLiteral)
                .map(|node| node.string_value.clone())
                .collect();
            assert_eq!(values, vec![expected], "{source}, escapes={escapes:?}");
        }
    }

    /// The callee token of a free-function call is the only occurrence a call
    /// site leaves behind when the function is not indexed (#3466). Member
    /// calls stay member-position-only, and a composite callee expression
    /// names its own callee at an inner node.
    #[test]
    #[brokk_bifrost_test_macros::hardwon(
        "#3466: C/C++ resolver call sites had no boundary row or callee occurrence"
    )]
    fn cpp_free_function_callees_are_value_references() {
        let source = concat!(
            "int bound(void) { return 1; }\n",
            "struct Widget { int method(void) { return 0; } };\n",
            "int go(struct Widget *widget) {\n",
            "    return getenv(\"PATH\") != 0\n",
            "        + ns::getenv(\"USER\") != 0\n",
            "        + bound()\n",
            "        + widget->method()\n",
            "        + bound()();\n",
            "}\n",
        );
        let mut parser = Parser::new();
        parser
            .set_language(&tree_sitter_cpp::LANGUAGE.into())
            .expect("C++ grammar");
        let tree = parser.parse(source, None).expect("C++ parse");
        assert!(
            !tree.root_node().has_error(),
            "{}",
            tree.root_node().to_sexp()
        );

        // Drive the same extraction entry the file walk drives: every fact
        // node admitted by the compiled kind table, through a real RoleSink.
        // The sink addresses occurrences by fact id, so the test keeps the
        // fact id to start byte mapping to name the tokens.
        let language: tree_sitter::Language = tree_sitter_cpp::LANGUAGE.into();
        let compiled = CompiledKinds::compile(&language, CPP_STRUCTURAL_SPEC.kind_table());
        let mut start_by_fact = HashMap::default();
        let mut extractions = Vec::new();
        let mut pending = vec![tree.root_node()];
        while let Some(node) = pending.pop() {
            if node.is_named()
                && let Some(kind) = compiled.kind_of(&node)
                && CPP_STRUCTURAL_SPEC.should_extract(node, kind)
            {
                start_by_fact.insert(node.id(), node.start_byte());
                extractions.push((node.start_byte(), node, kind));
            }
            for index in (0..node.named_child_count()).rev() {
                if let Some(child) = node.named_child(index) {
                    pending.push(child);
                }
            }
        }
        extractions.sort_by_key(|(start, _, _)| *start);
        let mut source_facts =
            brokk_bifrost_core::analyzer::source_facts::PrimarySourceFactCollector::new(source);
        let parents = ParentIndex::new(tree.root_node());
        let mut sink = RoleSink::new(source, &mut source_facts, 64, None, &parents);
        for (_, node, kind) in extractions {
            CPP_STRUCTURAL_SPEC.extract(node, kind, &mut sink);
        }
        let (_, _, occurrences, _, stop) = sink.into_parts();
        assert_eq!(stop, None);

        let roles_at = |needle: &str| {
            let start = source.find(needle).expect("fixture token");
            occurrences
                .iter()
                .filter(|occurrence| start_by_fact[&occurrence.target_node] == start)
                .map(|occurrence| occurrence.role)
                .collect::<Vec<_>>()
        };
        // Free-function callees are value reads, including a qualified callee
        // whose terminal name is the identifier and the callee of the inner
        // call in `bound()()`.
        assert_eq!(
            roles_at("getenv(\"PATH\")"),
            vec![OccurrenceRole::ValueReference]
        );
        assert_eq!(
            roles_at("getenv(\"USER\")"),
            vec![OccurrenceRole::ValueReference],
            "the terminal name of a qualified callee is the value read"
        );
        assert_eq!(roles_at("bound()\n"), vec![OccurrenceRole::ValueReference]);
        // A member call's terminal field stays one member-position occurrence;
        // the call itself adds no second row for the same token.
        assert_eq!(roles_at("method()"), vec![OccurrenceRole::MemberPosition]);
        // The receiver of a member call is neither a value read of the callee
        // nor a member position.
        assert!(roles_at("widget->").is_empty());
    }

    /// Tree-sitter recovers the valid `this->operator[](...)` expression as a
    /// call whose function is the unfactored `this` node. That node must not
    /// receive a value-reference occurrence role.
    #[test]
    fn cpp_subscript_operator_through_this_does_not_emit_role_for_non_fact() {
        collect_cpp_structural_facts(
            "struct Channel { int operator[](int); int at(int i) { return this->operator[](i); } };",
        );
    }
}

#[cfg(test)]
mod grammar_boundary_tests {
    use super::*;

    #[test]
    fn expression_and_pointer_declarator_name_fields() {
        let source = "void run() { auto p = new ns::Widget(); receiver.method<int>(); int (*callback)(int) = nullptr; int (ordinary)(int); }";
        let tree = crate::diagnostics::parse_cpp_tree(source);
        assert!(
            !tree.root_node().has_error(),
            "{}",
            tree.root_node().to_sexp()
        );
        let mut stack = vec![tree.root_node()];
        let mut names = Vec::new();
        let mut binders = Vec::new();
        while let Some(node) = stack.pop() {
            if matches!(node.kind(), "new_expression" | "field_expression") {
                let field = if node.kind() == "new_expression" {
                    "type"
                } else {
                    "field"
                };
                let child = node.child_by_field_name(field).unwrap();
                names.push((
                    node.kind(),
                    child.kind(),
                    expression_name_node(node).map(|n| &source[n.byte_range()]),
                ));
            }
            if node.kind() == "identifier"
                && let Some(name @ ("callback" | "ordinary")) = node_text(node, source)
            {
                let wrapper = if name == "callback" {
                    "pointer_declarator"
                } else {
                    "parenthesized_declarator"
                };
                assert_eq!(node.parent().unwrap().kind(), wrapper);
                binders.push((
                    name,
                    cpp_binder_owner(node, |n| n.parent(), field_name_in_parent)
                        .is_some_and(|owner| matches!(owner, CppBinderOwner::Local(_))),
                ));
            }
            stack.extend(
                node.named_children(&mut node.walk())
                    .collect::<Vec<_>>()
                    .into_iter()
                    .rev(),
            );
        }
        assert_eq!(
            names,
            [
                ("new_expression", "qualified_identifier", Some("Widget")),
                ("field_expression", "template_method", Some("method"))
            ]
        );
        assert_eq!(binders, [("callback", true), ("ordinary", false)]);
    }

    #[test]
    #[brokk_bifrost_test_macros::hardwon(
        "6ec52f232835: quicksilver round 4 survivor review: dependent member names lost their terminal token"
    )]
    fn dependent_member_name_grammar_boundary() {
        let source = "template<class T> void f(T receiver) { receiver.template method<int>(); }";
        let tree = crate::diagnostics::parse_cpp_tree(source);
        assert!(!tree.root_node().has_error());
        let mut stack = vec![tree.root_node()];
        let mut names = Vec::new();
        while let Some(node) = stack.pop() {
            if node.kind() == "dependent_name" {
                assert!(node.child_by_field_name("name").is_none());
                assert_eq!(node.named_child(0).unwrap().kind(), "template_method");
                assert_eq!(
                    declarator_name_node(node).map(|name| &source[name.byte_range()]),
                    Some("method")
                );
                assert_eq!(
                    terminal_callee_leaf(node.parent().unwrap(), callee_spine_step)
                        .map(|name| &source[name.byte_range()]),
                    Some("method")
                );
                names.push(expression_name_node(node).map(|n| &source[n.byte_range()]));
            }
            stack.extend(node.named_children(&mut node.walk()));
        }
        assert_eq!(names, [Some("method")]);
    }

    #[test]
    fn conditional_macro_name_fields() {
        let source = "#if ON\n#define FIRST(x) x\n#elif ALT\n#define SECOND(x) x\n#else\n#define THIRD(x) x\n#endif\nvoid f() {}\n";
        let tree = crate::diagnostics::parse_cpp_tree(source);
        assert!(!tree.root_node().has_error());
        let mut stack = vec![tree.root_node()];
        let mut definitions = Vec::new();
        while let Some(node) = stack.pop() {
            if node.kind() == "preproc_function_def" {
                let name = node.child_by_field_name("name").unwrap();
                definitions.push((
                    node_text(name, source).unwrap(),
                    node.parent().unwrap().kind(),
                ));
            }
            stack.extend(
                node.named_children(&mut node.walk())
                    .collect::<Vec<_>>()
                    .into_iter()
                    .rev(),
            );
        }
        assert_eq!(
            definitions,
            [
                ("FIRST", "preproc_if"),
                ("SECOND", "preproc_elif"),
                ("THIRD", "preproc_else"),
            ]
        );
        let mut names: Vec<_> = function_like_macro_names(tree.root_node(), source)
            .into_iter()
            .collect();
        names.sort();
        assert_eq!(names, ["FIRST", "SECOND", "THIRD"]);
    }
}

#[cfg(test)]
mod result_use_tests {
    use super::{CppCallResultUseIndex, cpp_call_result_use};
    use brokk_bifrost_core::analyzer::structural::result_use::{
        CallResultUse, CallResultUseOpenReason, IntentionalDiscardKind,
    };
    use tree_sitter::Parser;

    fn tree(source: &str) -> tree_sitter::Tree {
        let mut parser = Parser::new();
        parser
            .set_language(&tree_sitter_cpp::LANGUAGE.into())
            .expect("C++ grammar");
        parser.parse(source, None).expect("C++ tree")
    }

    fn calls<'tree>(tree: &'tree tree_sitter::Tree, source: &str) -> Vec<tree_sitter::Node<'tree>> {
        let mut found = Vec::new();
        let mut stack = vec![tree.root_node()];
        while let Some(node) = stack.pop() {
            if node.kind() == "call_expression" && !super::cpp_cast_call(node, source) {
                found.push(node);
            }
            for index in (0..node.named_child_count()).rev() {
                stack.push(node.named_child(index).expect("named child"));
            }
        }
        found.sort_by_key(|node| node.start_byte());
        found
    }

    #[test]
    fn expression_statement_void_cast_and_nested_contexts_are_distinct() {
        let source = concat!(
            "int f();\n",
            "void sink(int);\n",
            "void run() {\n",
            "    f();\n",
            "    (void)f();\n",
            "    static_cast<void>(f());\n",
            "    sink(f());\n",
            "    return;\n",
            "}\n",
        );
        let tree = tree(source);
        assert!(
            !tree.root_node().has_error(),
            "{}",
            tree.root_node().to_sexp()
        );
        let calls = calls(&tree, source);
        assert_eq!(calls.len(), 5);
        assert_eq!(
            cpp_call_result_use(calls[0], source).for_port(0),
            CallResultUse::Discarded
        );
        assert!(matches!(
            cpp_call_result_use(calls[1], source).for_port(0),
            CallResultUse::IntentionalDiscard(IntentionalDiscardKind::CppVoidCast)
        ));
        assert!(matches!(
            cpp_call_result_use(calls[2], source).for_port(0),
            CallResultUse::IntentionalDiscard(IntentionalDiscardKind::CppVoidCast)
        ));
        assert_eq!(
            cpp_call_result_use(calls[3], source).for_port(0),
            CallResultUse::Discarded
        );
        assert_eq!(
            cpp_call_result_use(calls[4], source).for_port(0),
            CallResultUse::Consumed
        );
    }

    #[test]
    fn lambda_tail_and_recovered_syntax_are_open() {
        // The macro-declaration grammar splits a bare `f(,)` into an
        // identifier and a separate ERROR with no call expression at all, so
        // the recovered call is spelled `f(+)` here: it still produces a
        // call_expression whose argument list carries the ERROR that marks
        // the syntax as recovered.
        let source = "int f(); void run() { auto value = [] { return f(); }; f(+); }";
        let tree = tree(source);
        assert!(tree.root_node().has_error());
        let calls = calls(&tree, source);
        assert!(matches!(
            cpp_call_result_use(calls[0], source).for_port(0),
            CallResultUse::Open(CallResultUseOpenReason::DeferredContext)
        ));
        assert_eq!(
            cpp_call_result_use(calls[1], source).for_port(0),
            CallResultUse::Open(CallResultUseOpenReason::RecoveredSyntax)
        );
    }

    #[test]
    fn exact_index_keeps_call_spans_separate() {
        let source = "int f(); void run() { f(); }";
        let tree = tree(source);
        let calls = calls(&tree, source);
        let index = CppCallResultUseIndex::new(tree.root_node(), source);
        assert_eq!(
            index
                .at_span(calls[0].start_byte(), calls[0].end_byte())
                .expect("indexed call")
                .for_port(0),
            CallResultUse::Discarded
        );
        assert!(index.at_span(source.len(), source.len()).is_err());
    }

    #[test]
    fn result_use_grammar_boundary_sites_and_recovery() {
        // Spellings are the independent site oracle: casts are syntax wrappers,
        // allocations are expressions, and an ERROR ancestor invalidates a site.
        for (source, expected) in [
            (
                "void run() { dynamic_cast<T*>(a()); static_cast<T*>(b()); reinterpret_cast<T*>(c()); const_cast<T*>(d()); new W(); auto p = new X(); sink(new Y()); }",
                vec![
                    ("a()", CallResultUse::Consumed),
                    ("b()", CallResultUse::Consumed),
                    ("c()", CallResultUse::Consumed),
                    ("d()", CallResultUse::Consumed),
                    ("new W()", CallResultUse::Discarded),
                    ("new X()", CallResultUse::Consumed),
                    ("sink(new Y())", CallResultUse::Discarded),
                    ("new Y()", CallResultUse::Consumed),
                ],
            ),
            (
                "void run() { try { f(); } }",
                vec![(
                    "f()",
                    CallResultUse::Open(CallResultUseOpenReason::RecoveredSyntax),
                )],
            ),
        ] {
            let tree = tree(source);
            let mut stack = vec![tree.root_node()];
            let mut grammar_sites = Vec::new();
            let mut recovery_witness = false;
            while let Some(node) = stack.pop() {
                if matches!(node.kind(), "call_expression" | "new_expression") {
                    grammar_sites.push(node.byte_range());
                    if source[node.byte_range()] == *"f()" {
                        assert!(!node.has_error());
                        assert!(!node.parent().unwrap().is_error());
                        let mut parent = node.parent();
                        while let Some(ancestor) = parent {
                            recovery_witness |= ancestor.is_error();
                            parent = ancestor.parent();
                        }
                    }
                }
                stack.extend(node.named_children(&mut node.walk()));
            }
            if source.contains("try") {
                assert!(recovery_witness, "{}", tree.root_node().to_sexp());
            } else {
                assert!(!tree.root_node().has_error());
                assert_eq!(
                    grammar_sites.len(),
                    12,
                    "four cast wrappers plus eight sites"
                );
            }
            let index = CppCallResultUseIndex::new(tree.root_node(), source);
            let actual: Vec<_> = index
                .sites()
                .iter()
                .map(|site| (&source[site.start_byte..site.end_byte], site.for_port(0)))
                .collect();
            assert_eq!(actual, expected, "{source}");
        }
    }

    #[test]
    #[brokk_bifrost_test_macros::hardwon(
        "6ec52f232835: quicksilver round 4 survivor review: void pointer casts falsely discarded source values"
    )]
    fn pointer_to_void_casts_consume_the_source_value() {
        let source = "int* make(); void run() { auto p = (void*)make(); auto q = static_cast<void*>(make()); }";
        let tree = tree(source);
        assert!(!tree.root_node().has_error());
        let mut stack = vec![tree.root_node()];
        let mut type_declarators = Vec::new();
        while let Some(node) = stack.pop() {
            if node.kind() == "type_descriptor" {
                type_declarators.push(node.child_by_field_name("declarator").map(|n| n.kind()));
            }
            stack.extend(node.named_children(&mut node.walk()));
        }
        assert_eq!(
            type_declarators,
            [
                Some("abstract_pointer_declarator"),
                Some("abstract_pointer_declarator")
            ]
        );
        let index = CppCallResultUseIndex::new(tree.root_node(), source);
        // Each source result feeds a pointer conversion and then an initializer.
        // Neither conversion discards a value by casting it to scalar void.
        let uses: Vec<_> = index.sites().iter().map(|site| site.for_port(0)).collect();
        assert_eq!(uses, [CallResultUse::Consumed, CallResultUse::Consumed]);
    }
}