Files
carbon-lang/toolchain/check/handle_function.cpp
T
Jon Ross-Perkins db022658c6 Implement syntactic merge checks for parameters. (#4149)
Note this isn't implementing checking through imports. The parse node
there is harder to access through the context, so would require
examining the entity in order to get the import declaration, to get at
the ImportIR. We also don't have a parse tree attached in that case, and
would need to add one to SemIR::File. But I believe we do want to add
that, so it's explicitly a TODO.

Note GetTokenText re-lexes literal values, so there's a bit of potential
overhead there. Not sure if we want a more efficient manner for
comparing in cases like this.
2024-07-23 20:32:24 +00:00

535 lines
22 KiB
C++

// 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/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/interface.h"
#include "toolchain/check/merge.h"
#include "toolchain/check/modifiers.h"
#include "toolchain/check/name_component.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/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);
// TODO: Use a dedicated instruction rather than VarStorage here.
context.AddInstAndPush<SemIR::VarStorage>(
node_id, {.type_id = type_id, .name_id = SemIR::NameId::ReturnSlot});
return true;
}
static auto DiagnoseModifiers(Context& context, DeclIntroducerState& introducer,
bool is_definition,
SemIR::InstId parent_scope_inst_id,
std::optional<SemIR::Inst> parent_scope_inst)
-> 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);
}
// Returns the return slot usage for a function given the computed usage for two
// different declarations of the function.
static auto MergeReturnSlot(SemIR::Function::ReturnSlot a,
SemIR::Function::ReturnSlot b)
-> SemIR::Function::ReturnSlot {
if (a == SemIR::Function::ReturnSlot::NotComputed) {
return b;
}
if (b == SemIR::Function::ReturnSlot::NotComputed) {
return a;
}
if (a == SemIR::Function::ReturnSlot::Error) {
return b;
}
if (b == SemIR::Function::ReturnSlot::Error) {
return a;
}
CARBON_CHECK(a == b)
<< "Different return slot usage computed for the same function.";
return a;
}
// 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, SemIRLoc new_loc,
SemIR::Function& new_function,
bool new_is_import, 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, {},
/*check_syntax=*/true)) {
return false;
}
CheckIsAllowedRedecl(context, Lex::TokenKind::Fn, prev_function.name_id,
{.loc = new_loc,
.is_definition = new_is_definition,
.is_extern = new_function.is_extern},
{.loc = prev_function.definition_id.is_valid()
? prev_function.definition_id
: prev_function.decl_id,
.is_definition = prev_function.definition_id.is_valid(),
.is_extern = prev_function.is_extern},
prev_import_ir_id);
if (new_is_definition) {
// Track the signature from the definition, so that IDs in the body
// match IDs in the signature.
prev_function.definition_id = new_function.definition_id;
prev_function.first_param_node_id = new_function.first_param_node_id;
prev_function.last_param_node_id = new_function.last_param_node_id;
prev_function.implicit_param_refs_id = new_function.implicit_param_refs_id;
prev_function.param_refs_id = new_function.param_refs_id;
prev_function.return_storage_id = new_function.return_storage_id;
}
// The new function might have return slot information if it was imported.
prev_function.return_slot =
MergeReturnSlot(prev_function.return_slot, new_function.return_slot);
if ((prev_import_ir_id.is_valid() && !new_is_import) ||
(prev_function.is_extern && !new_function.is_extern)) {
prev_function.is_extern = new_function.is_extern;
prev_function.decl_id = new_function.decl_id;
ReplacePrevInstForMerge(context, prev_function.parent_scope_id,
prev_function.name_id, new_function.decl_id);
}
return true;
}
// Check whether this is a redeclaration, merging if needed.
static auto TryMergeRedecl(Context& context, Parse::AnyFunctionDeclId node_id,
SemIR::InstId prev_id,
SemIR::FunctionDecl& function_decl,
SemIR::Function& function_info, bool is_definition)
-> void {
if (!prev_id.is_valid()) {
return;
}
auto prev_function_id = SemIR::FunctionId::Invalid;
auto prev_import_ir_id = SemIR::ImportIRId::Invalid;
CARBON_KIND_SWITCH(context.insts().Get(prev_id)) {
case CARBON_KIND(SemIR::FunctionDecl function_decl): {
prev_function_id = function_decl.function_id;
break;
}
case CARBON_KIND(SemIR::ImportRefLoaded import_ref): {
auto import_ir_inst =
context.import_ir_insts().Get(import_ref.import_ir_inst_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_import_ir_id = import_ir_inst.ir_id;
}
}
break;
}
default:
break;
}
if (!prev_function_id.is_valid()) {
context.DiagnoseDuplicateName(function_info.decl_id, prev_id);
return;
}
if (MergeFunctionRedecl(context, node_id, function_info,
/*new_is_import=*/false, 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;
}
}
// 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 decl_block_id = context.inst_block_stack().Pop();
auto return_storage_id = SemIR::InstId::Invalid;
auto return_slot = SemIR::Function::ReturnSlot::NotComputed;
if (auto [return_node, maybe_return_storage_id] =
context.node_stack().PopWithNodeIdIf<Parse::NodeKind::ReturnType>();
maybe_return_storage_id) {
return_storage_id = *maybe_return_storage_id;
} else {
// If there's no return type, there's no return slot.
return_slot = SemIR::Function::ReturnSlot::Absent;
}
auto name = PopNameComponent(context);
if (!name.params_id.is_valid()) {
context.TODO(node_id, "function with positional parameters");
name.params_id = SemIR::InstBlockId::Empty;
}
auto name_context = context.decl_name_stack().FinishName(name);
context.node_stack()
.PopAndDiscardSoloNodeId<Parse::NodeKind::FunctionIntroducer>();
// 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, introducer, is_definition, parent_scope_inst_id,
parent_scope_inst);
bool is_extern = introducer.modifier_set.HasAnyOf(KeywordModifierSet::Extern);
if (introducer.modifier_set.HasAnyOf(KeywordModifierSet::Method)) {
context.TODO(introducer.modifier_node_id(ModifierOrder::Decl),
"method modifier");
}
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");
}
// Add the function declaration.
auto function_decl = SemIR::FunctionDecl{
SemIR::TypeId::Invalid, SemIR::FunctionId::Invalid, decl_block_id};
auto decl_id =
context.AddPlaceholderInst(SemIR::LocIdAndInst(node_id, function_decl));
// 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_id = name_context.name_id_for_new_inst(),
.parent_scope_id = name_context.parent_scope_id_for_new_inst(),
.decl_id = decl_id,
.generic_id = SemIR::GenericId::Invalid,
.first_param_node_id = name.first_param_node_id,
.last_param_node_id = name.last_param_node_id,
.implicit_param_refs_id = name.implicit_params_id,
.param_refs_id = name.params_id,
.return_storage_id = return_storage_id,
.is_extern = is_extern,
.return_slot = return_slot};
if (is_definition) {
function_info.definition_id = decl_id;
}
TryMergeRedecl(context, node_id, name_context.prev_inst_id(), function_decl,
function_info, is_definition);
// Create a new function if this isn't a valid redeclaration.
if (!function_decl.function_id.is_valid()) {
function_info.generic_id = FinishGenericDecl(context, decl_id);
function_decl.function_id = context.functions().Add(function_info);
} else {
FinishGenericRedecl(context, decl_id, function_info.generic_id);
// TODO: Validate that the redeclaration doesn't set an access modifier.
}
function_decl.type_id = context.GetFunctionType(function_decl.function_id);
// TODO: Temporarily replace the return type with the canonical return type.
// This is a placeholder to avoid breaking tests before generic type
// substitution is ready.
if (return_storage_id.is_valid()) {
auto return_storage = context.insts().Get(return_storage_id);
return_storage.SetType(SemIR::GetTypeInInstance(
context.sem_ir(), SemIR::GenericInstanceId::Invalid,
return_storage.type_id()));
context.sem_ir().insts().Set(return_storage_id, return_storage);
}
// Write the function ID into the FunctionDecl.
context.ReplaceInstBeforeConstantUse(decl_id, function_decl);
// Check if we need to add this to name lookup, now that the function decl is
// done.
if (!name_context.prev_inst_id().is_valid()) {
// At interface scope, a function declaration introduces an associated
// function.
auto lookup_result_id = function_info.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,
introducer.modifier_set.GetAccessKind());
}
if (SemIR::IsEntryPoint(context.sem_ir(), function_decl.function_id)) {
auto return_type_id = function_info.declared_return_type(context.sem_ir());
// TODO: Update this once valid signatures for the entry point are decided.
if (function_info.implicit_param_refs_id.is_valid() ||
!function_info.param_refs_id.is_valid() ||
!context.inst_blocks().Get(function_info.param_refs_id).empty() ||
(return_type_id.is_valid() &&
return_type_id !=
context.GetBuiltinType(SemIR::BuiltinInstKind::IntType) &&
return_type_id != context.GetTupleType({}))) {
CARBON_DIAGNOSTIC(InvalidMainRunSignature, Error,
"Invalid signature for `Main.Run` function. Expected "
"`fn ()` or `fn () -> i32`.");
context.emitter().Emit(node_id, InvalidMainRunSignature);
}
}
if (!is_definition && context.IsImplFile() && !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;
}
// 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.scope_stack().Push(decl_id);
StartGenericDefinition(context);
context.AddCurrentCodeBlockToFunction();
// Check the return type is complete.
CheckFunctionReturnType(context, function.return_storage_id, function);
// Check the parameter types are complete.
for (auto param_id : llvm::concat<const SemIR::InstId>(
context.inst_blocks().GetOrEmpty(function.implicit_param_refs_id),
context.inst_blocks().GetOrEmpty(function.param_refs_id))) {
auto param = context.insts().Get(param_id);
// Find the parameter in the pattern.
// TODO: More general pattern handling?
if (auto addr_pattern = param.TryAs<SemIR::AddrPattern>()) {
param_id = addr_pattern->inner_id;
param = context.insts().Get(param_id);
}
// The parameter types need to be complete.
context.TryToCompleteType(param.type_id(), [&] {
CARBON_DIAGNOSTIC(
IncompleteTypeInFunctionParam, Error,
"Parameter has incomplete type `{0}` in function definition.",
SemIR::TypeId);
return context.emitter().Build(param_id, IncompleteTypeInFunctionParam,
param.type_id());
});
}
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 (context.is_current_position_reachable()) {
if (context.functions().Get(function_id).return_storage_id.is_valid()) {
CARBON_DIAGNOSTIC(
MissingReturnStatement, Error,
"Missing `return` at end of function with declared return type.");
context.emitter().Emit(TokenOnly(node_id), MissingReturnStatement);
} else {
context.AddInst<SemIR::Return>(node_id, {});
}
}
context.scope_stack().Pop();
context.inst_block_stack().Pop();
context.return_scope_stack().pop_back();
context.decl_name_stack().PopScope();
// If this is a generic function, collect information about the definition.
auto& function = context.functions().Get(function_id);
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 the builtin
// `builtin_inst_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_refs =
context.inst_blocks().GetOrEmpty(function.implicit_param_refs_id);
auto param_refs = context.inst_blocks().GetOrEmpty(function.param_refs_id);
param_type_ids.reserve(implicit_param_refs.size() + param_refs.size());
for (auto param_id :
llvm::concat<const SemIR::InstId>(implicit_param_refs, param_refs)) {
// 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.declared_return_type(context.sem_ir());
if (!return_type_id.is_valid()) {
return_type_id = context.GetTupleType({});
}
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);
if (IsValidBuiltinDeclaration(context, function, builtin_kind)) {
function.builtin_function_kind = builtin_kind;
} 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