t-ree 0.1.0

AST definitions for the T programming language
Documentation
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use std::collections::{HashMap, HashSet};

use crate::declaration::{Declaration, Module};
use crate::expression::{
    Binding, Block, Expression, ExpressionKind, Literal, MatchPattern, Span, Statement,
};
use crate::operator::{BinaryOperator, ComparisonOperator};
use crate::types::{IntWidth, Mutability, Signedness, Type};

fn spanned_error(span: Span, message: impl std::fmt::Display) -> String {
    if span.line > 0 {
        format!("{span}: {message}")
    } else {
        message.to_string()
    }
}

pub(crate) struct VariableInfo {
    variable_type: Type,
    auto_ref: bool,
}

pub(crate) struct ResolutionContext {
    newtypes: HashMap<String, Type>,
    return_types: HashMap<String, Type>,
    function_parameters: HashMap<String, Vec<Type>>,
    constant_types: HashMap<String, Type>,
    scopes: Vec<HashMap<String, VariableInfo>>,
    pointer_params: HashSet<String>,
    variadic_functions: HashSet<String>,
    current_return_type: Option<Type>,
}

impl ResolutionContext {
    fn new() -> Self {
        Self {
            newtypes: HashMap::new(),
            return_types: HashMap::new(),
            function_parameters: HashMap::new(),
            constant_types: HashMap::new(),
            scopes: Vec::new(),
            pointer_params: HashSet::new(),
            variadic_functions: HashSet::new(),
            current_return_type: None,
        }
    }

    fn push_scope(&mut self) {
        self.scopes.push(HashMap::new());
    }

    fn pop_scope(&mut self) {
        self.scopes.pop();
    }

    fn define_variable(&mut self, name: String, variable_type: Type, auto_ref: bool) {
        if let Some(scope) = self.scopes.last_mut() {
            scope.insert(
                name,
                VariableInfo {
                    variable_type,
                    auto_ref,
                },
            );
        }
    }

    fn lookup_variable_type(&self, name: &str) -> Option<Type> {
        for scope in self.scopes.iter().rev() {
            if let Some(info) = scope.get(name) {
                return Some(info.variable_type.clone());
            }
        }
        self.constant_types.get(name).cloned()
    }

    fn is_auto_ref(&self, name: &str) -> bool {
        self.scopes
            .iter()
            .rev()
            .any(|scope| scope.get(name).is_some_and(|info| info.auto_ref))
    }

    fn is_pointer_param(&self, name: &str) -> bool {
        self.pointer_params.contains(name)
    }

    fn is_known_name(&self, name: &str) -> bool {
        self.scopes.iter().any(|scope| scope.contains_key(name))
            || self.constant_types.contains_key(name)
            || self.return_types.contains_key(name)
            || self.newtypes.contains_key(name)
    }

    fn lookup_function_return(&self, name: &str) -> Option<Type> {
        self.return_types.get(name).cloned()
    }

    fn lookup_function_params(&self, name: &str) -> Option<&Vec<Type>> {
        self.function_parameters.get(name)
    }

    fn lookup_field(&self, type_name: &str, field_name: &str) -> Option<Type> {
        let inner = self.newtypes.get(type_name)?;
        if let Type::Tuple(fields) = inner {
            fields.iter().find_map(|f| {
                if let Type::Named(name) = f
                    && name == field_name
                {
                    Some(f.clone())
                } else {
                    None
                }
            })
        } else if inner.matches_name(field_name) {
            Some(inner.clone())
        } else {
            None
        }
    }

    fn resolve_named(&self, ty: &Type) -> Type {
        self.resolve_named_depth(ty, 0)
    }

    fn resolve_named_depth(&self, ty: &Type, depth: usize) -> Type {
        if depth > 100 {
            return ty.clone();
        }
        if let Type::Named(name) = ty
            && let Some(inner) = self.newtypes.get(name)
        {
            return self.resolve_named_depth(inner, depth + 1);
        }
        ty.clone()
    }

    fn strip_wrappers(ty: &Type) -> &Type {
        match ty {
            Type::Pointer(_, inner) | Type::Array(inner, _) | Type::Slice(_, inner) => {
                Self::strip_wrappers(inner)
            }
            Type::Vector(inner, _) => Self::strip_wrappers(inner),
            other => other,
        }
    }

    fn is_in_type_chain(&self, needle: &Type, haystack: &Type) -> bool {
        let mut current = haystack.clone();
        loop {
            if let Type::Named(name) = &current
                && let Some(inner) = self.newtypes.get(name)
            {
                if inner == needle {
                    return true;
                }
                current = inner.clone();
                continue;
            }
            return false;
        }
    }

    fn types_conflict(&self, type_a: &Type, type_b: &Type) -> bool {
        let core_a = Self::strip_wrappers(type_a);
        let core_b = Self::strip_wrappers(type_b);
        if core_a == core_b {
            return true;
        }
        self.is_in_type_chain(core_a, core_b) || self.is_in_type_chain(core_b, core_a)
    }

    fn resolve_underlying(&self, resolved_type: &Type) -> Type {
        match resolved_type {
            Type::Named(name) => self.newtypes.get(name).map_or_else(
                || resolved_type.clone(),
                |inner| self.resolve_underlying(inner),
            ),
            Type::Pointer(mutability, inner) => {
                Type::Pointer(*mutability, Box::new(self.resolve_underlying(inner)))
            }
            other => other.clone(),
        }
    }
}

/// Resolves types across a module, replacing all `resolved_type` fields
/// with correct types based on scope analysis, field resolution, and validation.
///
/// When `check_duplicate_types` is true, rejects functions with same-type parameters.
pub fn resolve_module(module: &mut Module, check_duplicate_types: bool) -> Vec<String> {
    let mut context = ResolutionContext::new();
    let mut errors = Vec::new();

    for declaration in module.iter() {
        match declaration {
            Declaration::Type(newtype) => {
                if context.newtypes.contains_key(&newtype.name) {
                    errors.push(format!("duplicate type definition: '{}'", newtype.name));
                }
                context
                    .newtypes
                    .insert(newtype.name.clone(), newtype.inner_type.clone());
            }
            Declaration::Function(function) => {
                context
                    .return_types
                    .insert(function.name.clone(), function.return_type.clone());
                context.function_parameters.insert(
                    function.name.clone(),
                    function
                        .parameters
                        .iter()
                        .filter_map(|p| p.parameter_type.clone())
                        .collect(),
                );
            }
            Declaration::Extern(ext) => {
                context
                    .return_types
                    .insert(ext.name.clone(), ext.return_type.clone());
                context.function_parameters.insert(
                    ext.name.clone(),
                    ext.parameters
                        .parameters()
                        .iter()
                        .filter_map(|p| p.parameter_type.clone())
                        .collect(),
                );
                if matches!(
                    ext.parameters,
                    crate::declaration::ParameterList::Variadic(_)
                ) {
                    context.variadic_functions.insert(ext.name.clone());
                }
            }
            Declaration::Constant(constant) => {
                context
                    .constant_types
                    .insert(constant.name.clone(), constant.constant_type.clone());
            }
            Declaration::Import(_) => {}
        }
    }

    for declaration in module.iter_mut() {
        match declaration {
            Declaration::Function(function) => {
                context.push_scope();
                context.pointer_params.clear();
                context.current_return_type = Some(function.return_type.clone());
                for param in &function.parameters {
                    if let Some(ref parameter_type) = param.parameter_type {
                        let resolved = context.resolve_underlying(parameter_type);
                        let auto_ref = matches!(resolved, Type::Pointer(..));
                        if auto_ref {
                            context.pointer_params.insert(param.name.clone());
                        }
                        context.define_variable(
                            param.name.clone(),
                            parameter_type.clone(),
                            auto_ref,
                        );
                    }
                }
                if check_duplicate_types {
                    for param in &function.parameters {
                        if let Some(param_type) = &param.parameter_type {
                            let core = ResolutionContext::strip_wrappers(param_type);
                            if let Type::Named(type_name) = core {
                                if !context.newtypes.contains_key(type_name.as_str())
                                    && !context.return_types.contains_key(type_name.as_str())
                                {
                                    errors.push(spanned_error(
                                        function.span,
                                        format!(
                                            "in '{}': unknown type '{type_name}'",
                                            function.name
                                        ),
                                    ));
                                    continue;
                                }
                                if param.name != *type_name {
                                    errors.push(spanned_error(
                                        function.span,
                                        format!(
                                            "in '{}': parameter '{}' has named type {type_name} — use '{param_type}' shorthand instead",
                                            function.name, param.name
                                        ),
                                    ));
                                }
                            }
                        }
                    }
                    for (i, param_a) in function.parameters.iter().enumerate() {
                        for param_b in function.parameters.iter().skip(i + 1) {
                            if let (Some(type_a), Some(type_b)) =
                                (&param_a.parameter_type, &param_b.parameter_type)
                                && context.types_conflict(type_a, type_b)
                            {
                                errors.push(spanned_error(
                                    function.span,
                                    format!(
                                        "in '{}': parameters '{}' ({type_a}) and '{}' ({type_b}) have conflicting types — use distinct newtypes",
                                        function.name, param_a.name, param_b.name
                                    ),
                                ));
                            }
                        }
                    }
                }
                if let Err(error) = resolve_block(&mut function.body, &mut context) {
                    errors.push(error);
                }
                context.pop_scope();
                context.pointer_params.clear();
                context.current_return_type = None;
            }
            Declaration::Constant(constant) => {
                if let Err(error) = resolve_expression(&mut constant.value, &mut context) {
                    errors.push(error);
                }
            }
            _ => {}
        }
    }

    errors
}

fn resolve_block(block: &mut Block, context: &mut ResolutionContext) -> Result<(), String> {
    for statement in &mut block.statements {
        resolve_statement(statement, context)?;
    }
    if let Some(result) = &mut block.result {
        resolve_expression(result, context)?;
        let return_is_pointer = context
            .current_return_type
            .as_ref()
            .is_some_and(|t| matches!(context.resolve_underlying(t), Type::Pointer(..)));
        if !return_is_pointer {
            try_auto_deref_in_place(result, context);
        }
    }
    Ok(())
}

fn resolve_statement(
    statement: &mut Statement,
    context: &mut ResolutionContext,
) -> Result<(), String> {
    match statement {
        Statement::Expression(expression) => {
            resolve_expression(expression, context)?;
        }
        Statement::Let {
            name,
            binding,
            declared_type,
            value,
        } => {
            resolve_expression(value, context)?;
            if matches!(value.kind, ExpressionKind::Literal(Literal::Null))
                && let Some(declared) = declared_type.as_ref()
            {
                value.resolved_type = Some(declared.clone());
            }
            try_auto_deref_in_place(value, context);
            if let (Some(declared), Some(actual)) =
                (declared_type.as_ref(), value.resolved_type.as_ref())
            {
                let declared_resolved = context.resolve_underlying(declared);
                let actual_resolved = context.resolve_underlying(actual);
                if !types_compatible(&declared_resolved, &actual_resolved) {
                    return Err(format!(
                        "type mismatch in let '{name}': expected {declared}, got {actual}",
                    ));
                }
            }
            let Some(inner_type) = declared_type
                .clone()
                .or_else(|| value.resolved_type.clone())
            else {
                return Err("unresolved type in let binding".into());
            };
            let bound_type = wrap_binding_type(*binding, inner_type);
            let auto_ref = matches!(binding, Binding::Variable | Binding::Reference);
            context.define_variable(name.clone(), bound_type, auto_ref);
        }
        Statement::Assign(target, value) => {
            resolve_expression(target, context)?;
            resolve_expression(value, context)?;
            auto_deref_replace_target(target, context)?;
            try_auto_deref_in_place(target, context);
            try_auto_deref_in_place(value, context);
            check_replace_types(target, value)?;
        }
        Statement::Return(Some(expression)) => {
            resolve_expression(expression, context)?;
            try_auto_deref_for_context(expression, context.current_return_type.as_ref(), context);
            if let (Some(expected), Some(actual)) =
                (&context.current_return_type, &expression.resolved_type)
            {
                let expected_resolved = context.resolve_underlying(expected);
                let actual_resolved = context.resolve_underlying(actual);
                if !types_compatible(&expected_resolved, &actual_resolved) {
                    return Err(format!(
                        "return type mismatch: expected {expected}, got {actual}",
                    ));
                }
            }
        }
        Statement::Return(None) => {}
        Statement::Label {
            parameters,
            initial_arguments,
            ..
        } => {
            for (i, argument) in initial_arguments.iter_mut().enumerate() {
                resolve_expression(argument, context)?;
                let param_type = parameters.get(i).and_then(|p| p.parameter_type.as_ref());
                try_auto_deref_for_context(argument, param_type, context);
            }
            for (i, param) in parameters.iter_mut().enumerate() {
                if param.parameter_type.is_none()
                    && let Some(argument) = initial_arguments.get(i)
                {
                    param.parameter_type.clone_from(&argument.resolved_type);
                }
            }
            for param in parameters.iter() {
                if let Some(ref parameter_type) = param.parameter_type {
                    context.define_variable(param.name.clone(), parameter_type.clone(), false);
                }
            }
        }
        Statement::Jump { arguments, .. } => {
            for argument in arguments.iter_mut() {
                resolve_expression(argument, context)?;
                try_auto_deref_in_place(argument, context);
            }
        }
        Statement::MultiReplace {
            bindings,
            targets,
            values,
        } => {
            for value in values.iter_mut() {
                resolve_expression(value, context)?;
                try_auto_deref_in_place(value, context);
            }
            for target in targets.iter_mut() {
                resolve_expression(target, context)?;
                auto_deref_replace_target(target, context)?;
                try_auto_deref_in_place(target, context);
            }
            for (index, binding) in bindings.iter().enumerate() {
                if let Some((name, bind_mode)) = binding
                    && let Some(target_type) = targets[index].resolved_type.clone()
                {
                    let resolved = context.resolve_named(&target_type);
                    let derefed = match resolved {
                        Type::Pointer(_, inner) => *inner,
                        other => other,
                    };
                    let auto_ref = matches!(bind_mode, Binding::Variable | Binding::Reference);
                    context.define_variable(
                        name.clone(),
                        wrap_binding_type(*bind_mode, derefed),
                        auto_ref,
                    );
                }
            }
        }
        Statement::Defer(inner) => {
            resolve_statement(inner, context)?;
        }
    }
    Ok(())
}

fn resolve_expression(
    expression: &mut Expression,
    context: &mut ResolutionContext,
) -> Result<(), String> {
    match &mut expression.kind {
        ExpressionKind::Literal(literal) => {
            expression.resolved_type = Some(literal_type(literal));
        }
        ExpressionKind::Variable(name) => {
            if !context.is_known_name(name) {
                return Err(format!("undefined variable '{name}'"));
            }
            expression.resolved_type = context.lookup_variable_type(name);
        }
        ExpressionKind::BinaryOperation(operator, left, right) => {
            resolve_expression(left, context)?;
            resolve_expression(right, context)?;
            if matches!(left.kind, ExpressionKind::Literal(Literal::Null))
                && let Some(ref right_type) = right.resolved_type
            {
                left.resolved_type = Some(right_type.clone());
            }
            if matches!(right.kind, ExpressionKind::Literal(Literal::Null))
                && let Some(ref left_type) = left.resolved_type
            {
                right.resolved_type = Some(left_type.clone());
            }
            try_auto_deref_in_place(left, context);
            try_auto_deref_in_place(right, context);
            if matches!(
                operator,
                BinaryOperator::Comparison(
                    ComparisonOperator::Equal | ComparisonOperator::NotEqual
                )
            ) {
                let left_is_pointer = left
                    .resolved_type
                    .as_ref()
                    .is_some_and(|t| matches!(context.resolve_underlying(t), Type::Pointer(..)));
                let right_is_pointer = right
                    .resolved_type
                    .as_ref()
                    .is_some_and(|t| matches!(context.resolve_underlying(t), Type::Pointer(..)));
                let left_is_integer = left
                    .resolved_type
                    .as_ref()
                    .is_some_and(|t| matches!(context.resolve_underlying(t), Type::Int(..)));
                let right_is_integer = right
                    .resolved_type
                    .as_ref()
                    .is_some_and(|t| matches!(context.resolve_underlying(t), Type::Int(..)));
                if (left_is_pointer && right_is_integer) || (left_is_integer && right_is_pointer) {
                    return Err(spanned_error(
                        expression.span,
                        "cannot compare pointer with integer — use 'pointer == null' instead",
                    ));
                }
            }
            coerce_numeric_literals(left, right);
            coerce_mixed_newtypes(left, right, context);
            check_binary_operands(context, operator, left, right)?;
            expression.resolved_type = if let (Some(left_type), Some(right_type)) =
                (&left.resolved_type, &right.resolved_type)
                && is_pointer_arithmetic(context, operator, left_type, right_type)
            {
                if matches!(context.resolve_underlying(left_type), Type::Pointer(..)) {
                    Some(left_type.clone())
                } else {
                    Some(right_type.clone())
                }
            } else {
                left.resolved_type
                    .as_ref()
                    .map(|t| operator_result_type(operator, t))
            };
        }
        ExpressionKind::UnaryOperation(operator, operand) => {
            resolve_expression(operand, context)?;
            try_auto_deref_in_place(operand, context);
            expression.resolved_type = operand
                .resolved_type
                .as_ref()
                .map(|t| unary_result_type(operator, t));
        }
        ExpressionKind::Call(callee, arguments) => {
            resolve_expression(callee, context)?;

            if let ExpressionKind::Variable(ref name) = callee.kind
                && let Some(inner_type) = context.newtypes.get(name).cloned()
            {
                for arg in arguments.iter_mut() {
                    resolve_expression(arg, context)?;
                    try_auto_deref_in_place(arg, context);
                }
                let type_name = name.clone();
                if !matches!(inner_type, Type::Tuple(_)) {
                    if arguments.len() != 1 {
                        return Err(format!(
                            "'{type_name}': expected 1 value, got {}",
                            arguments.len()
                        ));
                    }
                    let value = arguments.pop().unwrap();
                    expression.kind =
                        ExpressionKind::Convert(Box::new(value), Type::Named(type_name.clone()));
                    expression.resolved_type = Some(Type::Named(type_name));
                    return Ok(());
                }
                let fields = match_fields_by_type_or_position(
                    &inner_type,
                    &type_name,
                    std::mem::take(arguments),
                )?;
                expression.kind = ExpressionKind::TypeConstruction(type_name.clone(), fields);
                expression.resolved_type = Some(Type::Named(type_name));
                if let ExpressionKind::TypeConstruction(ref name, ref fields) = expression.kind {
                    check_construction_fields(context, name, fields)?;
                }
                return Ok(());
            }

            let param_types = if let ExpressionKind::Variable(ref name) = callee.kind {
                context.lookup_function_params(name).cloned()
            } else {
                None
            };

            for arg in arguments.iter_mut() {
                resolve_expression(arg, context)?;
            }

            if let Some(ref params) = param_types {
                reorder_arguments_by_type(params, arguments, context);
            }

            for (i, arg) in arguments.iter_mut().enumerate() {
                let expects_pointer = param_types.as_ref().is_some_and(|params| {
                    i < params.len()
                        && matches!(context.resolve_named(&params[i]), Type::Pointer(..))
                });
                let arg_is_pointer = arg
                    .resolved_type
                    .as_ref()
                    .is_some_and(|t| matches!(context.resolve_underlying(t), Type::Pointer(..)));
                if !expects_pointer && !arg_is_pointer {
                    try_auto_deref_in_place(arg, context);
                }
            }

            if let Some(ref params) = param_types
                && let ExpressionKind::Variable(ref name) = callee.kind
                && arguments.len() != params.len()
                && !context.variadic_functions.contains(name.as_str())
            {
                return Err(format!(
                    "'{name}' expects {} argument{}, got {}",
                    params.len(),
                    if params.len() == 1 { "" } else { "s" },
                    arguments.len(),
                ));
            }

            if let Some(ref params) = param_types
                && let ExpressionKind::Variable(ref name) = callee.kind
                && !context.variadic_functions.contains(name.as_str())
            {
                for (index, (argument, expected)) in arguments.iter().zip(params.iter()).enumerate()
                {
                    if let Some(actual) = &argument.resolved_type {
                        let expected_resolved = context.resolve_underlying(expected);
                        let actual_resolved = context.resolve_underlying(actual);
                        if !types_compatible(&expected_resolved, &actual_resolved) {
                            return Err(format!(
                                "'{name}' argument {}: expected {expected}, got {actual}",
                                index + 1
                            ));
                        }
                    }
                }
            }

            expression.resolved_type = if let ExpressionKind::Variable(ref name) = callee.kind {
                context.lookup_function_return(name)
            } else if let Some(callee_type) = &callee.resolved_type
                && let Type::Function(signature) = context.resolve_named(callee_type)
            {
                Some(*signature.return_type)
            } else {
                None
            };
        }
        ExpressionKind::Field(object, field_name) => {
            resolve_expression(object, context)?;
            let Some(object_type) = object.resolved_type.as_ref() else {
                return Err(spanned_error(
                    expression.span,
                    format!("cannot access field '{field_name}' on expression with unknown type"),
                ));
            };
            expression.resolved_type = Some(
                resolve_field_type(object_type, field_name, context)
                    .map_err(|error| spanned_error(expression.span, error))?,
            );
        }
        ExpressionKind::Index(array, index) => {
            resolve_expression(array, context)?;
            resolve_expression(index, context)?;
            try_auto_deref_in_place(index, context);
            expression.resolved_type = array
                .resolved_type
                .as_ref()
                .map(|t| resolve_index_type(t, context));
        }
        ExpressionKind::Dereference(operand) => {
            resolve_expression(operand, context)?;
            let is_pointer = operand
                .resolved_type
                .as_ref()
                .is_some_and(|t| matches!(context.resolve_named(t), Type::Pointer(..)));
            if is_pointer {
                expression.resolved_type = operand.resolved_type.as_ref().map(|t| {
                    if let Type::Pointer(_, inner) = context.resolve_named(t) {
                        *inner
                    } else {
                        unreachable!()
                    }
                });
            } else {
                let placeholder = Expression::new(
                    ExpressionKind::Literal(Literal::Bool(false)),
                    Some(Type::Bool),
                );
                let old = std::mem::replace(expression, placeholder);
                if let ExpressionKind::Dereference(operand) = old.kind {
                    *expression = *operand;
                }
            }
        }
        ExpressionKind::Convert(operand, target_type) => {
            resolve_expression(operand, context)?;
            if let Some(ref source_type) = operand.resolved_type
                && source_type == target_type
            {
                return Err(spanned_error(
                    expression.span,
                    format!("unnecessary cast: {source_type} is already {target_type}"),
                ));
            }
            let target_is_pointer =
                matches!(context.resolve_underlying(target_type), Type::Pointer(..));
            if !target_is_pointer && !is_pointer_param_chain(operand, context) {
                try_auto_deref_in_place(operand, context);
            }
            expression.resolved_type = Some(target_type.clone());
        }
        ExpressionKind::Transmute(operand, target_type) => {
            let span = expression.span;
            resolve_expression(operand, context)?;
            if let Some(ref source_type) = operand.resolved_type {
                let source_resolved = context.resolve_underlying(source_type);
                let target_resolved = context.resolve_underlying(target_type);
                let source_is_pointer = matches!(source_resolved, Type::Pointer(..));
                let target_is_pointer = matches!(target_resolved, Type::Pointer(..));
                let source_is_integer = matches!(source_resolved, Type::Int(..));
                let target_is_integer = matches!(target_resolved, Type::Int(..));
                if !source_is_pointer && !target_is_pointer {
                    return Err(spanned_error(
                        span,
                        format!(
                            "'as' is only for pointer casts — use '{target_type}: value' for conversions",
                        ),
                    ));
                }
                if source_is_pointer && !target_is_pointer && !target_is_integer {
                    return Err(spanned_error(
                        span,
                        format!(
                            "pointer can only be cast to integer or other pointer, not {target_type}",
                        ),
                    ));
                }
                if !source_is_pointer && !source_is_integer && target_is_pointer {
                    return Err(spanned_error(
                        span,
                        format!(
                            "only integers or pointers can be cast to pointer, not {source_type}",
                        ),
                    ));
                }
                if matches!(source_resolved, Type::Pointer(Mutability::Shared, _))
                    && matches!(target_resolved, Type::Pointer(Mutability::Mutable, _))
                {
                    return Err(spanned_error(
                        span,
                        format!("cannot cast &T to |T: {source_type} as {target_type}"),
                    ));
                }
            }
            expression.resolved_type = Some(target_type.clone());
        }
        ExpressionKind::SizeOf(_) => {
            expression.resolved_type = Some(Type::Int(IntWidth::WSize, Signedness::Unsigned));
        }
        ExpressionKind::TypeConstruction(name, fields) => {
            for (field_name, value) in fields.iter_mut() {
                resolve_expression(value, context)?;
                let field_type = context
                    .newtypes
                    .get(field_name)
                    .map(|_| Type::Named(field_name.clone()));
                try_auto_deref_for_context(value, field_type.as_ref(), context);
            }
            check_construction_fields(context, name, fields)?;
            expression.resolved_type = Some(Type::Named(name.clone()));
        }
        ExpressionKind::ArrayLiteral(elements) => {
            for element in elements.iter_mut() {
                resolve_expression(element, context)?;
                try_auto_deref_in_place(element, context);
            }
            let element_type = elements.first().and_then(|e| e.resolved_type.clone());
            let length = elements.len();
            if let Some(element_type) = element_type {
                let new_type = match &expression.resolved_type {
                    Some(Type::Vector(_, _)) => Type::Vector(Box::new(element_type), length),
                    _ => Type::Array(Box::new(element_type), length),
                };
                expression.resolved_type = Some(new_type);
            }
        }
        ExpressionKind::TupleLiteral(elements) => {
            for element in elements.iter_mut() {
                resolve_expression(element, context)?;
                try_auto_deref_in_place(element, context);
            }
            let types: Option<Vec<Type>> =
                elements.iter().map(|e| e.resolved_type.clone()).collect();
            expression.resolved_type = types.map(Type::Tuple);
        }
        ExpressionKind::Block(block) => {
            resolve_block(block, context)?;
            expression.resolved_type = Some(block_result_type(block));
        }
        ExpressionKind::If {
            condition,
            then_branch,
            else_branch,
        } => {
            resolve_expression(condition, context)?;
            try_auto_deref_in_place(condition, context);
            if let Some(ref condition_type) = condition.resolved_type {
                let resolved = context.resolve_underlying(condition_type);
                if matches!(resolved, Type::Pointer(..)) {
                    return Err(spanned_error(
                        condition.span,
                        "if-condition must be bool, not a pointer — use 'pointer != null' instead",
                    ));
                }
            }
            resolve_block(then_branch, context)?;
            if let Some(else_branch) = else_branch {
                resolve_block(else_branch, context)?;
            }
            expression.resolved_type = Some(block_result_type(then_branch));
        }
        ExpressionKind::Match { value, arms } => {
            resolve_expression(value, context)?;
            try_auto_deref_in_place(value, context);
            for arm in arms.iter_mut() {
                context.push_scope();
                if let MatchPattern::Variant(type_name, binding_name) = &arm.pattern {
                    if let Some(inner) = context.newtypes.get(type_name).cloned() {
                        let binding_type = context.resolve_named(&inner);
                        context.define_variable(binding_name.clone(), binding_type, false);
                    }
                } else if let MatchPattern::Variable(binding_name) = &arm.pattern
                    && let Some(ref value_type) = value.resolved_type
                {
                    context.define_variable(binding_name.clone(), value_type.clone(), false);
                }
                resolve_block(&mut arm.body, context)?;
                context.pop_scope();
            }
            expression.resolved_type = Some(
                arms.first()
                    .map_or_else(Type::unit, |arm| block_result_type(&arm.body)),
            );
        }
        ExpressionKind::Replace(target, value) => {
            resolve_expression(target, context)?;
            resolve_expression(value, context)?;
            auto_deref_replace_target(target, context)?;
            try_auto_deref_in_place(target, context);
            try_auto_deref_in_place(value, context);
            expression.resolved_type.clone_from(&target.resolved_type);

            check_replace_types(target, value)?;
        }
        ExpressionKind::OpAssign(_, target, value) => {
            resolve_expression(target, context)?;
            resolve_expression(value, context)?;
            auto_deref_replace_target(target, context)?;
            try_auto_deref_in_place(target, context);
            try_auto_deref_in_place(value, context);
            expression.resolved_type.clone_from(&target.resolved_type);
        }
        ExpressionKind::Slice(array, start, end) => {
            resolve_expression(array, context)?;
            if let Some(start) = start {
                resolve_expression(start, context)?;
                try_auto_deref_in_place(start, context);
            }
            if let Some(end) = end {
                resolve_expression(end, context)?;
                try_auto_deref_in_place(end, context);
            }
            expression.resolved_type = array.resolved_type.as_ref().map(|t| {
                let resolved = context.resolve_named(t);
                let element_type = match &resolved {
                    Type::Array(inner, _) => (**inner).clone(),
                    _ => resolved,
                };
                Type::Slice(Mutability::Shared, Box::new(element_type))
            });
        }
        ExpressionKind::Print(args) => {
            for arg in args.iter_mut() {
                resolve_expression(arg, context)?;
                try_auto_deref_in_place(arg, context);
            }
            expression.resolved_type = Some(Type::unit());
        }
    }
    Ok(())
}

mod helpers;
use helpers::*;