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carbon-lang/toolchain/check/handle_function.cpp
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Dana Jansens 6dbcc78e6c Rewrite symbolic constants in generic redeclarations (#5154) 
When a generic function declaration was encountered for the second or
more time, we would FinishGenericRedecl() for the function decl, but
this just popped the generic region stack and moved on.

The issue with that is when the stack entry is gone, we lose the
symbolic constants from that declaration, and are unable to rewrite them
to point to the actual generic. This left us with a function declaration
with abstract symbolic values that were not useful, and in a function
call we use the declaration attached to the definition, which would be a
declaration with broken symbolic values. Then the function would be
uncallable since deduce would be unable to determine argument types
without the generic bindings.

This resolves the issue for functions, as well as ensuring the correct
generic id from a previous declaration is used for other generic entity
types that have redeclarations.

When a function declaration is qualified, such as defining a class
method outside the class body, we need only the function declaration to
contribute to its generic region stack. The code was collecting constant
values from all qualifier segments together incorrectly.

So when we PushNameQualifierScope(), we also drop the current generic
region stack and rewrite its constant values by calling
FinishGenericRedecl(), and open a new stack entry for the next part of
the qualified declaration.

If a generic declaration somehow has more dependent instruction than a
previous declaration, it would add new instructions to its eval block
with indices beyond the elements in the actual declaration eval block,
since we only store the block from the first declaration found. To avoid
this we plumb through that we are in a redeclaration, and terminate with
an ICE instead of adding new instructions to crash on later.

Fixes #5136.
2025-03-21 22:26:08 +00:00

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// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
// Exceptions. See /LICENSE for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
#include "toolchain/base/kind_switch.h"
#include "toolchain/check/context.h"
#include "toolchain/check/control_flow.h"
#include "toolchain/check/convert.h"
#include "toolchain/check/decl_introducer_state.h"
#include "toolchain/check/decl_name_stack.h"
#include "toolchain/check/function.h"
#include "toolchain/check/generic.h"
#include "toolchain/check/handle.h"
#include "toolchain/check/import.h"
#include "toolchain/check/import_ref.h"
#include "toolchain/check/inst.h"
#include "toolchain/check/interface.h"
#include "toolchain/check/keyword_modifier_set.h"
#include "toolchain/check/literal.h"
#include "toolchain/check/merge.h"
#include "toolchain/check/modifiers.h"
#include "toolchain/check/name_component.h"
#include "toolchain/check/name_lookup.h"
#include "toolchain/check/type.h"
#include "toolchain/check/type_completion.h"
#include "toolchain/lex/token_kind.h"
#include "toolchain/parse/node_ids.h"
#include "toolchain/sem_ir/builtin_function_kind.h"
#include "toolchain/sem_ir/entry_point.h"
#include "toolchain/sem_ir/function.h"
#include "toolchain/sem_ir/ids.h"
#include "toolchain/sem_ir/pattern.h"
#include "toolchain/sem_ir/typed_insts.h"
namespace Carbon::Check {
auto HandleParseNode(Context& context, Parse::FunctionIntroducerId node_id)
-> bool {
// Create an instruction block to hold the instructions created as part of the
// function signature, such as parameter and return types.
context.inst_block_stack().Push();
// Push the bracketing node.
context.node_stack().Push(node_id);
// Optional modifiers and the name follow.
context.decl_introducer_state_stack().Push<Lex::TokenKind::Fn>();
context.decl_name_stack().PushScopeAndStartName();
// The function is potentially generic.
StartGenericDecl(context);
return true;
}
auto HandleParseNode(Context& context, Parse::ReturnTypeId node_id) -> bool {
// Propagate the type expression.
auto [type_node_id, type_inst_id] = context.node_stack().PopExprWithNodeId();
auto type_id = ExprAsType(context, type_node_id, type_inst_id).type_id;
// If the previous node was `IdentifierNameBeforeParams`, then it would have
// caused these entries to be pushed to the pattern stacks. But it's possible
// to have a fn declaration without any parameters, in which case we find
// `IdentifierNameNotBeforeParams` on the node stack. Then these entries are
// not on the pattern stacks yet. They are only needed in that case if we have
// a return type, which we now know that we do.
if (context.node_stack().PeekNodeKind() ==
Parse::NodeKind::IdentifierNameNotBeforeParams) {
context.pattern_block_stack().Push();
context.full_pattern_stack().PushFullPattern(
FullPatternStack::Kind::ExplicitParamList);
}
auto return_slot_pattern_id = AddPatternInst<SemIR::ReturnSlotPattern>(
context, node_id, {.type_id = type_id, .type_inst_id = type_inst_id});
auto param_pattern_id = AddPatternInst<SemIR::OutParamPattern>(
context, node_id,
{.type_id = type_id,
.subpattern_id = return_slot_pattern_id,
.index = SemIR::CallParamIndex::None});
context.node_stack().Push(node_id, param_pattern_id);
return true;
}
// Returns the ID of the self parameter pattern, or None.
// TODO: Do this during initial traversal of implicit params.
static auto FindSelfPattern(Context& context,
SemIR::InstBlockId implicit_param_patterns_id)
-> SemIR::InstId {
auto implicit_param_patterns =
context.inst_blocks().GetOrEmpty(implicit_param_patterns_id);
if (const auto* i = llvm::find_if(implicit_param_patterns,
[&](auto implicit_param_id) {
return SemIR::IsSelfPattern(
context.sem_ir(), implicit_param_id);
});
i != implicit_param_patterns.end()) {
return *i;
}
return SemIR::InstId::None;
}
// Diagnoses issues with the modifiers, removing modifiers that shouldn't be
// present.
static auto DiagnoseModifiers(Context& context,
Parse::AnyFunctionDeclId node_id,
DeclIntroducerState& introducer,
bool is_definition,
SemIR::InstId parent_scope_inst_id,
std::optional<SemIR::Inst> parent_scope_inst,
SemIR::InstId self_param_id) -> void {
CheckAccessModifiersOnDecl(context, introducer, parent_scope_inst);
LimitModifiersOnDecl(context, introducer,
KeywordModifierSet::Access | KeywordModifierSet::Extern |
KeywordModifierSet::Method |
KeywordModifierSet::Interface);
RestrictExternModifierOnDecl(context, introducer, parent_scope_inst,
is_definition);
CheckMethodModifiersOnFunction(context, introducer, parent_scope_inst_id,
parent_scope_inst);
RequireDefaultFinalOnlyInInterfaces(context, introducer, parent_scope_inst);
if (introducer.modifier_set.HasAnyOf(KeywordModifierSet::Interface)) {
// TODO: Once we are saving the modifiers for a function, add check that
// the function may only be defined if it is marked `default` or `final`.
context.TODO(introducer.modifier_node_id(ModifierOrder::Decl),
"interface modifier");
}
if (!self_param_id.has_value() &&
introducer.modifier_set.HasAnyOf(KeywordModifierSet::Method)) {
CARBON_DIAGNOSTIC(VirtualWithoutSelf, Error, "virtual class function");
context.emitter().Emit(node_id, VirtualWithoutSelf);
introducer.modifier_set.Remove(KeywordModifierSet::Method);
}
}
// Returns the virtual-family modifier as an enum.
static auto GetVirtualModifier(const KeywordModifierSet& modifier_set)
-> SemIR::Function::VirtualModifier {
return modifier_set.ToEnum<SemIR::Function::VirtualModifier>()
.Case(KeywordModifierSet::Virtual,
SemIR::Function::VirtualModifier::Virtual)
.Case(KeywordModifierSet::Abstract,
SemIR::Function::VirtualModifier::Abstract)
.Case(KeywordModifierSet::Impl, SemIR::Function::VirtualModifier::Impl)
.Default(SemIR::Function::VirtualModifier::None);
}
// Tries to merge new_function into prev_function_id. Since new_function won't
// have a definition even if one is upcoming, set is_definition to indicate the
// planned result.
//
// If merging is successful, returns true and may update the previous function.
// Otherwise, returns false. Prints a diagnostic when appropriate.
static auto MergeFunctionRedecl(Context& context,
Parse::AnyFunctionDeclId node_id,
SemIR::Function& new_function,
bool new_is_definition,
SemIR::FunctionId prev_function_id,
SemIR::ImportIRId prev_import_ir_id) -> bool {
auto& prev_function = context.functions().Get(prev_function_id);
if (!CheckFunctionTypeMatches(context, new_function, prev_function)) {
return false;
}
DiagnoseIfInvalidRedecl(
context, Lex::TokenKind::Fn, prev_function.name_id,
RedeclInfo(new_function, node_id, new_is_definition),
RedeclInfo(prev_function, prev_function.latest_decl_id(),
prev_function.has_definition_started()),
prev_import_ir_id);
if (new_is_definition && prev_function.has_definition_started()) {
return false;
}
if (!prev_function.first_owning_decl_id.has_value()) {
prev_function.first_owning_decl_id = new_function.first_owning_decl_id;
}
if (new_is_definition) {
// Track the signature from the definition, so that IDs in the body
// match IDs in the signature.
prev_function.MergeDefinition(new_function);
prev_function.call_params_id = new_function.call_params_id;
prev_function.return_slot_pattern_id = new_function.return_slot_pattern_id;
prev_function.self_param_id = new_function.self_param_id;
}
if (prev_import_ir_id.has_value()) {
ReplacePrevInstForMerge(context, new_function.parent_scope_id,
prev_function.name_id,
new_function.first_owning_decl_id);
}
return true;
}
// Check whether this is a redeclaration, merging if needed.
static auto TryMergeRedecl(Context& context, Parse::AnyFunctionDeclId node_id,
const DeclNameStack::NameContext& name_context,
SemIR::FunctionDecl& function_decl,
SemIR::Function& function_info, bool is_definition)
-> void {
if (name_context.state == DeclNameStack::NameContext::State::Poisoned) {
DiagnosePoisonedName(context, name_context.name_id_for_new_inst(),
name_context.poisoning_loc_id, name_context.loc_id);
return;
}
auto prev_id = name_context.prev_inst_id();
if (!prev_id.has_value()) {
return;
}
auto prev_function_id = SemIR::FunctionId::None;
auto prev_type_id = SemIR::TypeId::None;
auto prev_import_ir_id = SemIR::ImportIRId::None;
CARBON_KIND_SWITCH(context.insts().Get(prev_id)) {
case CARBON_KIND(SemIR::FunctionDecl function_decl): {
prev_function_id = function_decl.function_id;
prev_type_id = function_decl.type_id;
break;
}
case SemIR::ImportRefLoaded::Kind: {
auto import_ir_inst = GetCanonicalImportIRInst(context, prev_id);
// Verify the decl so that things like aliases are name conflicts.
const auto* import_ir =
context.import_irs().Get(import_ir_inst.ir_id).sem_ir;
if (!import_ir->insts().Is<SemIR::FunctionDecl>(import_ir_inst.inst_id)) {
break;
}
// Use the type to get the ID.
if (auto struct_value = context.insts().TryGetAs<SemIR::StructValue>(
context.constant_values().GetConstantInstId(prev_id))) {
if (auto function_type = context.types().TryGetAs<SemIR::FunctionType>(
struct_value->type_id)) {
prev_function_id = function_type->function_id;
prev_type_id = struct_value->type_id;
prev_import_ir_id = import_ir_inst.ir_id;
}
}
break;
}
default:
break;
}
if (!prev_function_id.has_value()) {
DiagnoseDuplicateName(context, name_context.name_id, name_context.loc_id,
prev_id);
return;
}
if (MergeFunctionRedecl(context, node_id, function_info, is_definition,
prev_function_id, prev_import_ir_id)) {
// When merging, use the existing function rather than adding a new one.
function_decl.function_id = prev_function_id;
function_decl.type_id = prev_type_id;
}
}
// Adds the declaration to name lookup when appropriate.
static auto MaybeAddToNameLookup(
Context& context, const DeclNameStack::NameContext& name_context,
const KeywordModifierSet& modifier_set,
const std::optional<SemIR::Inst>& parent_scope_inst, SemIR::InstId decl_id)
-> void {
if (name_context.state == DeclNameStack::NameContext::State::Poisoned ||
name_context.prev_inst_id().has_value()) {
return;
}
// At interface scope, a function declaration introduces an associated
// function.
auto lookup_result_id = decl_id;
if (parent_scope_inst && !name_context.has_qualifiers) {
if (auto interface_scope =
parent_scope_inst->TryAs<SemIR::InterfaceDecl>()) {
lookup_result_id = BuildAssociatedEntity(
context, interface_scope->interface_id, decl_id);
}
}
context.decl_name_stack().AddName(name_context, lookup_result_id,
modifier_set.GetAccessKind());
}
// If the function is the entry point, do corresponding validation.
static auto ValidateForEntryPoint(Context& context,
Parse::AnyFunctionDeclId node_id,
SemIR::FunctionId function_id,
const SemIR::Function& function_info)
-> void {
if (!SemIR::IsEntryPoint(context.sem_ir(), function_id)) {
return;
}
auto return_type_id = function_info.GetDeclaredReturnType(context.sem_ir());
// TODO: Update this once valid signatures for the entry point are decided.
if (function_info.implicit_param_patterns_id.has_value() ||
!function_info.param_patterns_id.has_value() ||
!context.inst_blocks().Get(function_info.param_patterns_id).empty() ||
(return_type_id.has_value() &&
return_type_id != GetTupleType(context, {}) &&
// TODO: Decide on valid return types for `Main.Run`. Perhaps we should
// have an interface for this.
return_type_id != MakeIntType(context, node_id, SemIR::IntKind::Signed,
context.ints().Add(32)))) {
CARBON_DIAGNOSTIC(InvalidMainRunSignature, Error,
"invalid signature for `Main.Run` function; expected "
"`fn ()` or `fn () -> i32`");
context.emitter().Emit(node_id, InvalidMainRunSignature);
}
}
// Requests a vtable be created when processing a virtual function.
static auto RequestVtableIfVirtual(
Context& context, Parse::AnyFunctionDeclId node_id,
SemIR::Function::VirtualModifier virtual_modifier,
const std::optional<SemIR::Inst>& parent_scope_inst, SemIR::InstId decl_id)
-> void {
// In order to request a vtable, the function must be virtual, and in a class
// scope.
if (virtual_modifier == SemIR::Function::VirtualModifier::None ||
!parent_scope_inst) {
return;
}
auto class_decl = parent_scope_inst->TryAs<SemIR::ClassDecl>();
if (!class_decl) {
return;
}
auto& class_info = context.classes().Get(class_decl->class_id);
if (virtual_modifier == SemIR::Function::VirtualModifier::Impl &&
!class_info.base_id.has_value()) {
CARBON_DIAGNOSTIC(ImplWithoutBase, Error, "impl without base class");
context.emitter().Emit(node_id, ImplWithoutBase);
}
// TODO: If this is an `impl` function, check there's a matching base
// function that's impl or virtual.
class_info.is_dynamic = true;
context.vtable_stack().AddInstId(decl_id);
}
// Validates the `destroy` function's signature. May replace invalid values for
// recovery.
static auto ValidateIfDestroy(Context& context, bool is_redecl,
std::optional<SemIR::Inst> parent_scope_inst,
SemIR::Function& function_info) -> void {
if (function_info.name_id != SemIR::NameId::Destroy) {
return;
}
// For recovery, always force explicit parameters to be empty. We do this
// before any of the returns for simplicity.
auto orig_param_patterns_id = function_info.param_patterns_id;
function_info.param_patterns_id = SemIR::InstBlockId::Empty;
// Use differences on merge to diagnose remaining issues.
if (is_redecl) {
return;
}
if (!parent_scope_inst || !parent_scope_inst->Is<SemIR::ClassDecl>()) {
CARBON_DIAGNOSTIC(DestroyFunctionOutsideClass, Error,
"declaring `fn destroy` in non-class scope");
context.emitter().Emit(function_info.latest_decl_id(),
DestroyFunctionOutsideClass);
return;
}
if (!function_info.self_param_id.has_value()) {
CARBON_DIAGNOSTIC(DestroyFunctionMissingSelf, Error,
"missing implicit `self` parameter");
context.emitter().Emit(function_info.latest_decl_id(),
DestroyFunctionMissingSelf);
return;
}
// `self` must be the only implicit parameter.
if (auto block =
context.inst_blocks().Get(function_info.implicit_param_patterns_id);
block.size() > 1) {
// Point at the first non-`self` parameter.
auto param_id = block[function_info.self_param_id == block[0] ? 1 : 0];
CARBON_DIAGNOSTIC(DestroyFunctionUnexpectedImplicitParam, Error,
"unexpected implicit parameter");
context.emitter().Emit(param_id, DestroyFunctionUnexpectedImplicitParam);
return;
}
if (!orig_param_patterns_id.has_value()) {
CARBON_DIAGNOSTIC(DestroyFunctionPositionalParams, Error,
"missing empty explicit parameter list");
context.emitter().Emit(function_info.latest_decl_id(),
DestroyFunctionPositionalParams);
return;
}
if (orig_param_patterns_id != SemIR::InstBlockId::Empty) {
CARBON_DIAGNOSTIC(DestroyFunctionNonEmptyExplicitParams, Error,
"unexpected parameter");
context.emitter().Emit(context.inst_blocks().Get(orig_param_patterns_id)[0],
DestroyFunctionNonEmptyExplicitParams);
return;
}
if (auto return_type_id =
function_info.GetDeclaredReturnType(context.sem_ir());
return_type_id.has_value() &&
return_type_id != GetTupleType(context, {})) {
CARBON_DIAGNOSTIC(DestroyFunctionIncorrectReturnType, Error,
"incorrect return type; must be unspecified or `()`");
context.emitter().Emit(function_info.return_slot_pattern_id,
DestroyFunctionIncorrectReturnType);
return;
}
}
// Diagnoses when positional params aren't supported. Reassigns the pattern
// block if needed.
static auto DiagnosePositionalParams(Context& context,
SemIR::Function& function_info) -> void {
if (function_info.param_patterns_id.has_value()) {
return;
}
context.TODO(function_info.latest_decl_id(),
"function with positional parameters");
function_info.param_patterns_id = SemIR::InstBlockId::Empty;
}
// Build a FunctionDecl describing the signature of a function. This
// handles the common logic shared by function declaration syntax and function
// definition syntax.
static auto BuildFunctionDecl(Context& context,
Parse::AnyFunctionDeclId node_id,
bool is_definition)
-> std::pair<SemIR::FunctionId, SemIR::InstId> {
auto return_slot_pattern_id = SemIR::InstId::None;
if (auto [return_node, maybe_return_slot_pattern_id] =
context.node_stack().PopWithNodeIdIf<Parse::NodeKind::ReturnType>();
maybe_return_slot_pattern_id) {
return_slot_pattern_id = *maybe_return_slot_pattern_id;
}
auto name = PopNameComponent(context, return_slot_pattern_id);
auto name_context = context.decl_name_stack().FinishName(name);
context.node_stack()
.PopAndDiscardSoloNodeId<Parse::NodeKind::FunctionIntroducer>();
auto self_param_id =
FindSelfPattern(context, name.implicit_param_patterns_id);
// Process modifiers.
auto [parent_scope_inst_id, parent_scope_inst] =
context.name_scopes().GetInstIfValid(name_context.parent_scope_id);
auto introducer =
context.decl_introducer_state_stack().Pop<Lex::TokenKind::Fn>();
DiagnoseModifiers(context, node_id, introducer, is_definition,
parent_scope_inst_id, parent_scope_inst, self_param_id);
bool is_extern = introducer.modifier_set.HasAnyOf(KeywordModifierSet::Extern);
auto virtual_modifier = GetVirtualModifier(introducer.modifier_set);
// Add the function declaration.
SemIR::FunctionDecl function_decl = {SemIR::TypeId::None,
SemIR::FunctionId::None,
context.inst_block_stack().Pop()};
auto decl_id = AddPlaceholderInst(context, node_id, function_decl);
RequestVtableIfVirtual(context, node_id, virtual_modifier, parent_scope_inst,
decl_id);
// Build the function entity. This will be merged into an existing function if
// there is one, or otherwise added to the function store.
auto function_info =
SemIR::Function{name_context.MakeEntityWithParamsBase(
name, decl_id, is_extern, introducer.extern_library),
{.call_params_id = name.call_params_id,
.return_slot_pattern_id = name.return_slot_pattern_id,
.virtual_modifier = virtual_modifier,
.self_param_id = self_param_id}};
if (is_definition) {
function_info.definition_id = decl_id;
}
// Analyze standard function signatures before positional parameters, so that
// we can have more specific diagnostics and recovery.
bool is_redecl =
name_context.state == DeclNameStack::NameContext::State::Resolved;
ValidateIfDestroy(context, is_redecl, parent_scope_inst, function_info);
DiagnosePositionalParams(context, function_info);
TryMergeRedecl(context, node_id, name_context, function_decl, function_info,
is_definition);
// Create a new function if this isn't a valid redeclaration.
if (!function_decl.function_id.has_value()) {
if (function_info.is_extern && context.sem_ir().is_impl()) {
DiagnoseExternRequiresDeclInApiFile(context, node_id);
}
function_info.generic_id = BuildGenericDecl(context, decl_id);
function_decl.function_id = context.functions().Add(function_info);
function_decl.type_id =
GetFunctionType(context, function_decl.function_id,
context.scope_stack().PeekSpecificId());
} else {
auto prev_decl_generic_id =
context.functions().Get(function_decl.function_id).generic_id;
FinishGenericRedecl(context, prev_decl_generic_id);
// TODO: Validate that the redeclaration doesn't set an access modifier.
}
// Write the function ID into the FunctionDecl.
ReplaceInstBeforeConstantUse(context, decl_id, function_decl);
// Diagnose 'definition of `abstract` function' using the canonical Function's
// modifiers.
if (is_definition &&
context.functions().Get(function_decl.function_id).virtual_modifier ==
SemIR::Function::VirtualModifier::Abstract) {
CARBON_DIAGNOSTIC(DefinedAbstractFunction, Error,
"definition of `abstract` function");
context.emitter().Emit(TokenOnly(node_id), DefinedAbstractFunction);
}
// Add to name lookup if needed, now that the decl is built.
MaybeAddToNameLookup(context, name_context, introducer.modifier_set,
parent_scope_inst, decl_id);
ValidateForEntryPoint(context, node_id, function_decl.function_id,
function_info);
if (!is_definition && context.sem_ir().is_impl() && !is_extern) {
context.definitions_required().push_back(decl_id);
}
return {function_decl.function_id, decl_id};
}
auto HandleParseNode(Context& context, Parse::FunctionDeclId node_id) -> bool {
BuildFunctionDecl(context, node_id, /*is_definition=*/false);
context.decl_name_stack().PopScope();
return true;
}
static auto CheckFunctionDefinitionSignature(Context& context,
SemIR::Function& function)
-> void {
auto params_to_complete =
context.inst_blocks().GetOrEmpty(function.call_params_id);
// Check the return type is complete.
if (function.return_slot_pattern_id.has_value()) {
CheckFunctionReturnType(
context, context.insts().GetLocId(function.return_slot_pattern_id),
function, SemIR::SpecificId::None);
params_to_complete = params_to_complete.drop_back();
}
// Check the parameter types are complete.
for (auto param_ref_id : params_to_complete) {
if (param_ref_id == SemIR::ErrorInst::SingletonInstId) {
continue;
}
// The parameter types need to be complete.
RequireCompleteType(
context, context.insts().GetAs<SemIR::AnyParam>(param_ref_id).type_id,
context.insts().GetLocId(param_ref_id), [&] {
CARBON_DIAGNOSTIC(
IncompleteTypeInFunctionParam, Error,
"parameter has incomplete type {0} in function definition",
TypeOfInstId);
return context.emitter().Build(
param_ref_id, IncompleteTypeInFunctionParam, param_ref_id);
});
}
}
// Processes a function definition after a signature for which we have already
// built a function ID. This logic is shared between processing regular function
// definitions and delayed parsing of inline method definitions.
static auto HandleFunctionDefinitionAfterSignature(
Context& context, Parse::FunctionDefinitionStartId node_id,
SemIR::FunctionId function_id, SemIR::InstId decl_id) -> void {
auto& function = context.functions().Get(function_id);
// Create the function scope and the entry block.
context.return_scope_stack().push_back({.decl_id = decl_id});
context.inst_block_stack().Push();
context.region_stack().PushRegion(context.inst_block_stack().PeekOrAdd());
context.scope_stack().Push(decl_id);
StartGenericDefinition(context);
CheckFunctionDefinitionSignature(context, function);
context.node_stack().Push(node_id, function_id);
}
auto HandleFunctionDefinitionSuspend(Context& context,
Parse::FunctionDefinitionStartId node_id)
-> SuspendedFunction {
// Process the declaration portion of the function.
auto [function_id, decl_id] =
BuildFunctionDecl(context, node_id, /*is_definition=*/true);
return {.function_id = function_id,
.decl_id = decl_id,
.saved_name_state = context.decl_name_stack().Suspend()};
}
auto HandleFunctionDefinitionResume(Context& context,
Parse::FunctionDefinitionStartId node_id,
SuspendedFunction suspended_fn) -> void {
context.decl_name_stack().Restore(suspended_fn.saved_name_state);
HandleFunctionDefinitionAfterSignature(
context, node_id, suspended_fn.function_id, suspended_fn.decl_id);
}
auto HandleParseNode(Context& context, Parse::FunctionDefinitionStartId node_id)
-> bool {
// Process the declaration portion of the function.
auto [function_id, decl_id] =
BuildFunctionDecl(context, node_id, /*is_definition=*/true);
HandleFunctionDefinitionAfterSignature(context, node_id, function_id,
decl_id);
return true;
}
auto HandleParseNode(Context& context, Parse::FunctionDefinitionId node_id)
-> bool {
SemIR::FunctionId function_id =
context.node_stack().Pop<Parse::NodeKind::FunctionDefinitionStart>();
// If the `}` of the function is reachable, reject if we need a return value
// and otherwise add an implicit `return;`.
if (IsCurrentPositionReachable(context)) {
if (context.functions()
.Get(function_id)
.return_slot_pattern_id.has_value()) {
CARBON_DIAGNOSTIC(
MissingReturnStatement, Error,
"missing `return` at end of function with declared return type");
context.emitter().Emit(TokenOnly(node_id), MissingReturnStatement);
} else {
AddInst<SemIR::Return>(context, node_id, {});
}
}
context.scope_stack().Pop();
context.inst_block_stack().Pop();
context.return_scope_stack().pop_back();
context.decl_name_stack().PopScope();
auto& function = context.functions().Get(function_id);
function.body_block_ids = context.region_stack().PopRegion();
// If this is a generic function, collect information about the definition.
FinishGenericDefinition(context, function.generic_id);
return true;
}
auto HandleParseNode(Context& context,
Parse::BuiltinFunctionDefinitionStartId node_id) -> bool {
// Process the declaration portion of the function.
auto [function_id, _] =
BuildFunctionDecl(context, node_id, /*is_definition=*/true);
context.node_stack().Push(node_id, function_id);
return true;
}
auto HandleParseNode(Context& context, Parse::BuiltinNameId node_id) -> bool {
context.node_stack().Push(node_id);
return true;
}
// Looks up a builtin function kind given its name as a string.
// TODO: Move this out to another file.
static auto LookupBuiltinFunctionKind(Context& context,
Parse::BuiltinNameId name_id)
-> SemIR::BuiltinFunctionKind {
auto builtin_name = context.string_literal_values().Get(
context.tokens().GetStringLiteralValue(
context.parse_tree().node_token(name_id)));
auto kind = SemIR::BuiltinFunctionKind::ForBuiltinName(builtin_name);
if (kind == SemIR::BuiltinFunctionKind::None) {
CARBON_DIAGNOSTIC(UnknownBuiltinFunctionName, Error,
"unknown builtin function name \"{0}\"", std::string);
context.emitter().Emit(name_id, UnknownBuiltinFunctionName,
builtin_name.str());
}
return kind;
}
// Returns whether `function` is a valid declaration of `builtin_kind`.
static auto IsValidBuiltinDeclaration(Context& context,
const SemIR::Function& function,
SemIR::BuiltinFunctionKind builtin_kind)
-> bool {
// Form the list of parameter types for the declaration.
llvm::SmallVector<SemIR::TypeId> param_type_ids;
auto implicit_param_patterns =
context.inst_blocks().GetOrEmpty(function.implicit_param_patterns_id);
auto param_patterns =
context.inst_blocks().GetOrEmpty(function.param_patterns_id);
param_type_ids.reserve(implicit_param_patterns.size() +
param_patterns.size());
for (auto param_id : llvm::concat<const SemIR::InstId>(
implicit_param_patterns, param_patterns)) {
// TODO: We also need to track whether the parameter is declared with
// `var`.
param_type_ids.push_back(context.insts().Get(param_id).type_id());
}
// Get the return type. This is `()` if none was specified.
auto return_type_id = function.GetDeclaredReturnType(context.sem_ir());
if (!return_type_id.has_value()) {
return_type_id = GetTupleType(context, {});
}
return builtin_kind.IsValidType(context.sem_ir(), param_type_ids,
return_type_id);
}
auto HandleParseNode(Context& context,
Parse::BuiltinFunctionDefinitionId /*node_id*/) -> bool {
auto name_id =
context.node_stack().PopForSoloNodeId<Parse::NodeKind::BuiltinName>();
auto [fn_node_id, function_id] =
context.node_stack()
.PopWithNodeId<Parse::NodeKind::BuiltinFunctionDefinitionStart>();
auto builtin_kind = LookupBuiltinFunctionKind(context, name_id);
if (builtin_kind != SemIR::BuiltinFunctionKind::None) {
auto& function = context.functions().Get(function_id);
CheckFunctionDefinitionSignature(context, function);
if (IsValidBuiltinDeclaration(context, function, builtin_kind)) {
function.builtin_function_kind = builtin_kind;
// Build an empty generic definition if this is a generic builtin.
StartGenericDefinition(context);
FinishGenericDefinition(context, function.generic_id);
} else {
CARBON_DIAGNOSTIC(InvalidBuiltinSignature, Error,
"invalid signature for builtin function \"{0}\"",
std::string);
context.emitter().Emit(fn_node_id, InvalidBuiltinSignature,
builtin_kind.name().str());
}
}
context.decl_name_stack().PopScope();
return true;
}
} // namespace Carbon::Check
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