weaveffi_model/

validate.rs

//! IDL validation. This module owns the [`ValidationError`] catalog and the
//! [`validate_api`] entry point; the work is split across submodules:
//! `rules` (per-module checks), `diagnostic` (miette span attachment), and
//! `warnings` (advisory lints).
//!
//! Validation collects *every* rule violation before failing, so a document
//! with several problems reports them all in one run rather than one per
//! invocation.

use crate::ir::{Api, SUPPORTED_VERSIONS};
#[cfg(feature = "idl")]
use miette::Diagnostic;
use std::collections::BTreeSet;

use crate::resolved::ResolvedApi;

mod diagnostic;
mod rules;
#[cfg(all(test, feature = "idl"))]
mod tests;
mod warnings;

pub use diagnostic::ValidationDiagnostic;
pub use warnings::{collect_warnings, ValidationWarning};

/// Every way an [`Api`] can fail validation.
///
/// `validate_api` collects every variant it encounters. Each variant carries
/// the names needed to render an actionable diagnostic, and the
/// `#[error]`/`#[diagnostic]` attributes supply the message and help text
/// shown to the user.
#[derive(Debug, thiserror::Error)]
#[cfg_attr(feature = "idl", derive(Diagnostic))]
pub enum ValidationError {
    /// A module is missing its required `name` field.
    #[error("module has no name")]
    #[cfg_attr(
        feature = "idl",
        diagnostic(help("every module must have a non-empty 'name' field"))
    )]
    NoModuleName,
    /// Two modules share the same name.
    #[error("duplicate module name: {0}")]
    #[cfg_attr(
        feature = "idl",
        diagnostic(help(
            "module names must be unique within an API definition; rename or merge the duplicate"
        ))
    )]
    DuplicateModuleName(String),
    /// A module name is not a valid identifier; the second field explains why.
    #[error("invalid module name '{0}': {1}")]
    #[cfg_attr(
        feature = "idl",
        diagnostic(help(
            "choose a valid identifier (a-z, A-Z, 0-9, _) that is not a reserved word"
        ))
    )]
    InvalidModuleName(String, &'static str),
    /// Two functions in the same module share a name.
    #[error("duplicate function name in module '{module}': {function}")]
    #[cfg_attr(
        feature = "idl",
        diagnostic(help("function names must be unique within a module; rename the duplicate"))
    )]
    DuplicateFunctionName {
        /// Module that contains the colliding functions.
        module: String,
        /// Duplicated function name.
        function: String,
    },
    /// Two parameters of one function share a name.
    #[error("duplicate param name in function '{function}' of module '{module}': {param}")]
    #[cfg_attr(
        feature = "idl",
        diagnostic(help(
            "parameter names must be unique within a function; rename the duplicate"
        ))
    )]
    DuplicateParamName {
        /// Module that contains the function.
        module: String,
        /// Function that contains the colliding parameters.
        function: String,
        /// Duplicated parameter name.
        param: String,
    },
    /// A name matches a reserved keyword in one of the target languages.
    #[error("reserved keyword used: {0}")]
    #[cfg_attr(
        feature = "idl",
        diagnostic(help("choose a different name that is not a language reserved word"))
    )]
    ReservedKeyword(String),
    /// An identifier is malformed; the second field explains why.
    #[error("invalid identifier '{0}': {1}")]
    #[cfg_attr(feature = "idl", diagnostic(help("identifiers must start with a letter or underscore and contain only alphanumeric or underscore characters")))]
    InvalidIdentifier(String, &'static str),
    /// An error domain in the named module is missing its `name` field.
    #[error("error domain missing name in module '{0}'")]
    #[cfg_attr(
        feature = "idl",
        diagnostic(help("add a non-empty 'name' field to the error domain"))
    )]
    ErrorDomainMissingName(String),
    /// Two error codes in the same module share a name.
    #[error("duplicate error code name in module '{module}': {name}")]
    #[cfg_attr(
        feature = "idl",
        diagnostic(help("error code names must be unique within a module; rename the duplicate"))
    )]
    DuplicateErrorName {
        /// Module that contains the error domain.
        module: String,
        /// Duplicated error code name.
        name: String,
    },
    /// Two error codes in the same module share a numeric value.
    #[error("duplicate error numeric code in module '{module}': {code}")]
    #[cfg_attr(
        feature = "idl",
        diagnostic(help(
            "numeric error codes must be unique within a module; assign a different value"
        ))
    )]
    DuplicateErrorCode {
        /// Module that contains the error domain.
        module: String,
        /// Conflicting numeric error code.
        code: i32,
    },
    /// An error code uses a reserved value: `0` means success and the
    /// negative range belongs to the runtime's trap codes.
    #[error("invalid error code in module '{module}' for '{name}': must be a positive integer")]
    #[cfg_attr(
        feature = "idl",
        diagnostic(help(
            "0 means success and negative codes are reserved for the runtime (-1 generic, \
         -2 panic, -3 marshalling failure, -4 foreign callback error, -5 cancelled); use a positive integer"
        ))
    )]
    InvalidErrorCode {
        /// Module that contains the error domain.
        module: String,
        /// Error code name with the invalid value.
        name: String,
    },
    /// A function name collides with an error domain name in the same module.
    #[error("function name collides with error domain name in module '{module}': {name}")]
    #[cfg_attr(
        feature = "idl",
        diagnostic(help(
            "function and error domain names share a namespace; rename one to avoid the collision"
        ))
    )]
    NameCollisionWithErrorDomain {
        /// Module where the collision occurs.
        module: String,
        /// Name shared by the function and the error domain.
        name: String,
    },
    /// Two declarations lower to the same C identifier.
    ///
    /// Every function, type, constant, and runtime name in the C ABI starts
    /// with the library prefix and is flattened from its module path, so
    /// `m.x_y`, `m.x.y`, and `m_x.y` all become `{prefix}_m_x_y`, and an
    /// async `foo`'s completion type `{prefix}_m_foo_callback` collides with
    /// a function named `foo_callback`.
    #[error("C symbol collision: {first} and {second} both lower to '{symbol}'")]
    #[cfg_attr(
        feature = "idl",
        diagnostic(help(
            "every C identifier is the library prefix plus the underscore-joined module path \
         plus the declaration name; rename one of the colliding declarations"
        ))
    )]
    SymbolCollision {
        /// The colliding C identifier.
        symbol: String,
        /// The declaration that claimed the identifier first.
        first: String,
        /// The declaration that collided with it.
        second: String,
    },
    /// A synchronous callable declares `cancellable: true`.
    #[error("function '{module}::{function}' is cancellable but not async")]
    #[cfg_attr(
        feature = "idl",
        diagnostic(help(
            "only async functions take a cancel token; add `async: true` or remove \
         `cancellable: true`"
        ))
    )]
    CancellableNotAsync {
        /// Module that contains the function.
        module: String,
        /// The offending function.
        function: String,
    },
    /// A function declares `throws: true` but no error domain is in scope.
    #[error("function '{module}::{function}' declares throws but no error domain is in scope")]
    #[cfg_attr(
        feature = "idl",
        diagnostic(help(
            "a throwing function reports codes from its module's error domain; declare an \
         `errors:` block on this module (or an ancestor module), or remove `throws: true`"
        ))
    )]
    ThrowsWithoutErrorDomain {
        /// Module that contains the function.
        module: String,
        /// Function marked `throws` with no domain in scope.
        function: String,
    },
    /// Two types (structs, enums, interfaces, or callback interfaces) share a
    /// bare name.
    ///
    /// Type names must be unique across the whole API: generators emit flat
    /// per-language type names, and unqualified cross-module references
    /// resolve by bare name, so two types called `Config` would collide in
    /// generated code and make references ambiguous.
    #[error("duplicate type name '{name}' (declared in '{first}' and '{second}')")]
    #[cfg_attr(
        feature = "idl",
        diagnostic(help(
            "struct, enum, interface, callback interface, and error domain names must be unique \
         across the whole API; rename one of the declarations"
        ))
    )]
    DuplicateTypeName {
        /// The colliding bare type name.
        name: String,
        /// Module path of the first declaration.
        first: String,
        /// Module path of the second declaration.
        second: String,
    },
    /// Two error domains declare a code with the same name.
    ///
    /// Code names must be unique across every domain in the API: backends
    /// with flat namespaces (Python, Node, Go) derive one error class or
    /// constant per code, so `NotFound` in two domains would collide in
    /// generated code.
    #[error("duplicate error code name '{name}' (declared in '{first}' and '{second}')")]
    #[cfg_attr(
        feature = "idl",
        diagnostic(help(
            "error code names must be unique across the whole API; qualify one of them \
         (e.g. 'OrderNotFound')"
        ))
    )]
    DuplicateErrorCodeName {
        /// The colliding code name.
        name: String,
        /// Domain of the first declaration, as `module.Domain`.
        first: String,
        /// Domain of the second declaration, as `module.Domain`.
        second: String,
    },
    /// Two structs in the same module share a name.
    #[error("duplicate struct name in module '{module}': {name}")]
    #[cfg_attr(
        feature = "idl",
        diagnostic(help("struct names must be unique within a module; rename the duplicate"))
    )]
    DuplicateStructName {
        /// Module that contains the structs.
        module: String,
        /// Duplicated struct name.
        name: String,
    },
    /// Two fields of one struct share a name.
    #[error("duplicate field name in struct '{struct_name}': {field}")]
    #[cfg_attr(
        feature = "idl",
        diagnostic(help("field names must be unique within a struct; rename the duplicate"))
    )]
    DuplicateStructField {
        /// Struct that contains the colliding fields.
        struct_name: String,
        /// Duplicated field name.
        field: String,
    },
    /// A struct declares no fields.
    #[error("empty struct in module '{module}': {name}")]
    #[cfg_attr(
        feature = "idl",
        diagnostic(help(
            "structs must have at least one field; add a field or remove the struct"
        ))
    )]
    EmptyStruct {
        /// Module that contains the struct.
        module: String,
        /// Name of the empty struct.
        name: String,
    },
    /// Two enums in the same module share a name.
    #[error("duplicate enum name in module '{module}': {name}")]
    #[cfg_attr(
        feature = "idl",
        diagnostic(help("enum names must be unique within a module; rename the duplicate"))
    )]
    DuplicateEnumName {
        /// Module that contains the enums.
        module: String,
        /// Duplicated enum name.
        name: String,
    },
    /// An enum declares no variants.
    #[error("empty enum in module '{module}': {name}")]
    #[cfg_attr(
        feature = "idl",
        diagnostic(help(
            "enums must have at least one variant; add a variant or remove the enum"
        ))
    )]
    EmptyEnum {
        /// Module that contains the enum.
        module: String,
        /// Name of the empty enum.
        name: String,
    },
    /// Two variants of one enum share a name.
    #[error("duplicate enum variant in enum '{enum_name}': {variant}")]
    #[cfg_attr(
        feature = "idl",
        diagnostic(help("variant names must be unique within an enum; rename the duplicate"))
    )]
    DuplicateEnumVariant {
        /// Enum that contains the colliding variants.
        enum_name: String,
        /// Duplicated variant name.
        variant: String,
    },
    /// Two associated fields of one rich enum variant share a name.
    #[error("duplicate field '{field}' in variant '{variant}' of enum '{enum_name}'")]
    #[cfg_attr(
        feature = "idl",
        diagnostic(help(
            "associated field names must be unique within an enum variant; rename the duplicate"
        ))
    )]
    DuplicateEnumVariantField {
        /// Enum that contains the variant.
        enum_name: String,
        /// Variant that contains the colliding fields.
        variant: String,
        /// Duplicated associated field name.
        field: String,
    },
    /// Two variants of one enum share a numeric discriminant.
    #[error("duplicate enum value in enum '{enum_name}': {value}")]
    #[cfg_attr(
        feature = "idl",
        diagnostic(help(
            "variant numeric values must be unique within an enum; assign a different value"
        ))
    )]
    DuplicateEnumValue {
        /// Enum that contains the variants.
        enum_name: String,
        /// Conflicting numeric discriminant.
        value: i32,
    },
    /// Two interfaces in the same module share a name.
    #[error("duplicate interface name in module '{module}': {name}")]
    #[cfg_attr(
        feature = "idl",
        diagnostic(help("interface names must be unique within a module; rename the duplicate"))
    )]
    DuplicateInterfaceName {
        /// Module that contains the interfaces.
        module: String,
        /// Duplicated interface name.
        name: String,
    },
    /// Two members (constructors, methods, or statics) of one interface share
    /// a name.
    #[error("duplicate member name in interface '{interface}': {name}")]
    #[cfg_attr(
        feature = "idl",
        diagnostic(help(
            "constructor, method, and static names share one namespace per interface; \
         rename the duplicate"
        ))
    )]
    DuplicateInterfaceMember {
        /// Interface that contains the colliding members.
        interface: String,
        /// Duplicated member name.
        name: String,
    },
    /// An interface declares no members at all.
    #[error("empty interface in module '{module}': {name}")]
    #[cfg_attr(
        feature = "idl",
        diagnostic(help(
            "interfaces must declare at least one constructor, method, or static; \
         add a member or remove the interface"
        ))
    )]
    EmptyInterface {
        /// Module that contains the interface.
        module: String,
        /// Name of the empty interface.
        name: String,
    },
    /// An interface constructor declares an explicit return type.
    #[error("constructor '{constructor}' of interface '{interface}' declares a return type")]
    #[cfg_attr(
        feature = "idl",
        diagnostic(help(
            "a constructor implicitly returns a new instance of its interface; remove the \
         `return` field"
        ))
    )]
    ConstructorHasReturn {
        /// Interface that declares the constructor.
        interface: String,
        /// The offending constructor.
        constructor: String,
    },
    /// An interface constructor is marked `async`.
    #[error("constructor '{constructor}' of interface '{interface}' cannot be async")]
    #[cfg_attr(
        feature = "idl",
        diagnostic(help(
            "constructors are synchronous; expose an async static factory returning the \
         interface instead"
        ))
    )]
    AsyncConstructor {
        /// Interface that declares the constructor.
        interface: String,
        /// The offending constructor.
        constructor: String,
    },
    /// An interface reference appears as a map key.
    #[error("interface type '{name}' is not valid in {location}")]
    #[cfg_attr(
        feature = "idl",
        diagnostic(help(
            "interface objects may appear anywhere except as map keys; key a map by a scalar, \
         string, or C-style enum instead"
        ))
    )]
    InterfaceInInvalidPosition {
        /// The referenced interface name.
        name: String,
        /// Position where the interface reference appeared.
        location: String,
    },
    /// A type reference names a struct, enum, interface, or callback interface
    /// that doesn't exist.
    #[error("unknown type reference: {name}")]
    #[cfg_attr(
        feature = "idl",
        diagnostic(help(
            "define a struct, enum, interface, or callback interface with this name, or check \
         for typos"
        ))
    )]
    UnknownTypeRef {
        /// Unresolved type name.
        name: String,
    },
    /// A map uses a key type the C ABI can't represent.
    #[error("invalid map key type: {key_type}; only integers, bools, strings, and C-style enums are allowed as map keys")]
    #[cfg_attr(feature = "idl", diagnostic(help("map keys must be integers (i8 through u64), bool, string, or a C-style enum; structs, rich enums, interfaces, optionals, lists, and maps cannot be keys")))]
    InvalidMapKey {
        /// Rejected key type, rendered as it appears in the IDL.
        key_type: String,
    },
    /// An iterator type appears somewhere other than a function return.
    #[error("iterator type is only valid as a function return type, found in {location}")]
    #[cfg_attr(feature = "idl", diagnostic(help("iterator types can only be used as function return types, not as parameters or struct fields")))]
    IteratorInInvalidPosition {
        /// Position where the iterator type appeared.
        location: String,
    },
    /// Two callback interfaces in the same module share a name.
    #[error("duplicate callback interface name in module '{module}': {name}")]
    #[cfg_attr(
        feature = "idl",
        diagnostic(help(
            "callback interface names must be unique within a module; rename the duplicate"
        ))
    )]
    DuplicateCallbackInterfaceName {
        /// Module that contains the callback interfaces.
        module: String,
        /// Duplicated callback interface name.
        name: String,
    },
    /// A callback interface declares no methods.
    #[error("empty callback interface in module '{module}': {name}")]
    #[cfg_attr(
        feature = "idl",
        diagnostic(help(
            "callback interfaces must declare at least one method; add a method or remove the \
         callback interface"
        ))
    )]
    EmptyCallbackInterface {
        /// Module that contains the callback interface.
        module: String,
        /// Name of the empty callback interface.
        name: String,
    },
    /// Two methods of one callback interface share a name.
    #[error("duplicate method name in callback interface '{interface}': {name}")]
    #[cfg_attr(
        feature = "idl",
        diagnostic(help(
            "method names must be unique within a callback interface; rename the duplicate"
        ))
    )]
    DuplicateCallbackMethod {
        /// Callback interface that contains the colliding methods.
        interface: String,
        /// Duplicated method name.
        name: String,
    },
    /// A callback-interface method uses a flag or return type the callback
    /// ABI can't carry. The `reason` names the offending feature.
    #[error("method '{method}' of callback interface '{interface}' {reason}")]
    #[cfg_attr(
        feature = "idl",
        diagnostic(help(
            "callback-interface methods are synchronous, never throw, and return either nothing \
         or a direct value (a scalar, bool, or C-style enum): the consumer implements them, \
         so no producer-owned allocation or error payload can flow back"
        ))
    )]
    InvalidCallbackMethod {
        /// Callback interface that declares the method.
        interface: String,
        /// The offending method.
        method: String,
        /// Why the method was rejected.
        reason: &'static str,
    },
    /// A callback-interface type appears in a position other than a callable
    /// parameter.
    #[error("callback interface '{name}' is not valid in {location}")]
    #[cfg_attr(
        feature = "idl",
        diagnostic(help(
            "a callback interface is a consumer-implemented vtable: it may be passed as a \
         parameter of a function, constructor, static, or method, but it can't be returned, \
         nested inside another type, or passed to another callback-interface method"
        ))
    )]
    CallbackInterfaceInInvalidPosition {
        /// The referenced callback interface name.
        name: String,
        /// Position where the reference appeared.
        location: String,
    },
    /// An async function tries to return an iterator, which has no async ABI.
    #[error("async function '{module}::{function}' cannot return an iterator")]
    #[cfg_attr(
        feature = "idl",
        diagnostic(help(
            "the callback-completed async ABI has no streaming protocol; return a list ([T]) \
         from the async function, or make the function synchronous and return iter<T>"
        ))
    )]
    AsyncIteratorReturn {
        /// Module that contains the function.
        module: String,
        /// Async function with the iterator return.
        function: String,
    },
    /// The document declares a schema version this build doesn't support.
    #[error("unsupported schema version '{version}'; supported versions: {supported}")]
    #[cfg_attr(
        feature = "idl",
        diagnostic(help(
            "set the version field to the current schema version and update the \
         document to match the current schema (see docs/src/reference/idl.md)"
        ))
    )]
    UnsupportedSchemaVersion {
        /// Version requested by the document.
        version: String,
        /// Comma-separated list of versions this build accepts.
        supported: String,
    },
}

/// Every validation failure found in one pass, each wrapped as a
/// [`ValidationDiagnostic`] carrying an optional source span.
///
/// `Display` renders every message on its own line; miette renderers reach the
/// individual diagnostics through [`Diagnostic::related`].
#[derive(Debug)]
pub struct ValidationDiagnostics {
    /// The individual failures, in the order they were found. Never empty.
    pub diagnostics: Vec<ValidationDiagnostic>,
}

impl ValidationDiagnostics {
    /// The first failure, which every report is guaranteed to contain.
    pub fn first(&self) -> &ValidationDiagnostic {
        &self.diagnostics[0]
    }
}

impl std::fmt::Display for ValidationDiagnostics {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        for (i, d) in self.diagnostics.iter().enumerate() {
            if i > 0 {
                writeln!(f)?;
            }
            write!(f, "{d}")?;
        }
        Ok(())
    }
}

impl std::error::Error for ValidationDiagnostics {}

#[cfg(feature = "idl")]
impl Diagnostic for ValidationDiagnostics {
    fn code<'a>(&'a self) -> Option<Box<dyn std::fmt::Display + 'a>> {
        self.first().code()
    }

    fn help<'a>(&'a self) -> Option<Box<dyn std::fmt::Display + 'a>> {
        self.first().help()
    }

    fn source_code(&self) -> Option<&dyn miette::SourceCode> {
        self.first().source_code()
    }

    fn labels(&self) -> Option<Box<dyn Iterator<Item = miette::LabeledSpan> + '_>> {
        self.first().labels()
    }

    fn related<'a>(&'a self) -> Option<Box<dyn Iterator<Item = &'a dyn Diagnostic> + 'a>> {
        if self.diagnostics.len() <= 1 {
            return None;
        }
        Some(Box::new(
            self.diagnostics[1..].iter().map(|d| d as &dyn Diagnostic),
        ))
    }
}

/// Validate an [`Api`] document, reporting **every** rule violation found.
/// The optional `source` is `(filename, contents)` of the IDL file and is
/// used to attach spans to the returned diagnostics. Pass `None` when the
/// API is constructed in memory (tests, programmatic builds) and there is no
/// on-disk source.
///
/// This is the one checked way to turn a parsed document into the
/// [`ResolvedApi`] every generator consumes. The document is never rewritten;
/// the resolved view indexes its declarations so that
/// [`ResolvedApi::resolve`] can turn each written reference into a
/// [`Ty`](crate::model::Ty) whose kind and owning module are known.
///
/// # Errors
///
/// Returns [`ValidationDiagnostics`] carrying one [`ValidationDiagnostic`]
/// per violation: an unsupported schema version, a duplicate or invalid name,
/// an unknown or misplaced type, an empty struct or enum, a `throws` without
/// an error domain, or any other rule violation in the catalog above.
pub fn validate_api(
    api: Api,
    source: Option<(&str, &str)>,
) -> Result<ResolvedApi, ValidationDiagnostics> {
    let errors = validate_api_inner(&api);
    if errors.is_empty() {
        return Ok(ResolvedApi::assume_valid(api));
    }
    Err(ValidationDiagnostics {
        diagnostics: errors
            .into_iter()
            .map(|e| ValidationDiagnostic::new(e, source))
            .collect(),
    })
}

fn validate_api_inner(api: &Api) -> Vec<ValidationError> {
    let mut errors = Vec::new();
    if !SUPPORTED_VERSIONS.contains(&api.version.as_str()) {
        // A wrong-schema document is checked no further: the rules below
        // assume the current schema's shape.
        return vec![ValidationError::UnsupportedSchemaVersion {
            version: api.version.clone(),
            supported: SUPPORTED_VERSIONS.join(", "),
        }];
    }
    let types = rules::TypeIndex::build(&api.modules);
    let mut module_names = BTreeSet::new();
    for m in &api.modules {
        if !module_names.insert(m.name.clone()) {
            errors.push(ValidationError::DuplicateModuleName(m.name.clone()));
        }
        rules::validate_module(m, &types, false, &mut errors);
    }
    rules::check_global_type_names(&api.modules, &mut errors);
    rules::check_global_error_code_names(&api.modules, &mut errors);
    if errors.is_empty() {
        check_symbol_collisions(api, &mut errors);
    }
    errors
}

/// Build the binding model (any prefix works: collisions are invariant under
/// a shared prefix) and reject any C identifier claimed twice.
fn check_symbol_collisions(api: &Api, errors: &mut Vec<ValidationError>) {
    let resolved = ResolvedApi::assume_valid(api.clone());
    let model = crate::model::BindingModel::build(&resolved);
    let mut seen: std::collections::BTreeMap<String, String> = std::collections::BTreeMap::new();
    let runtime = crate::model::RUNTIME_SYMBOLS.len();
    for (i, (symbol, origin)) in model.c_symbols().into_iter().enumerate() {
        let family = symbol
            .strip_prefix(&format!("{}_", model.prefix))
            .and_then(|rest| {
                crate::model::RESERVED_SYMBOL_FAMILIES
                    .iter()
                    .find(|f| rest.starts_with(*f))
            });
        if let (Some(family), true) = (family, i >= runtime) {
            errors.push(ValidationError::SymbolCollision {
                symbol: symbol.clone(),
                first: format!("the C value-buffer helpers ('{}_{family}*')", model.prefix),
                second: origin.clone(),
            });
        }
        match seen.get(&symbol) {
            Some(first) => errors.push(ValidationError::SymbolCollision {
                symbol,
                first: first.clone(),
                second: origin,
            }),
            None => {
                seen.insert(symbol, origin);
            }
        }
    }
}