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Unify MergeRedecl functions (#7632)

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As discussed in #7620.
This commit is contained in:
Özgür T. Önsoy
2026-08-25 18:43:52 +00:00
committed by GitHub
parent 1410795bf7
commit 2bdcb1fa62
17 changed files with 470 additions and 905 deletions
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toolchain/check/handle_class.cpp
+8 -125
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@@ -26,6 +26,7 @@
#include "toolchain/check/type_completion.h"
#include "toolchain/diagnostics/emitter.h"
#include "toolchain/parse/node_ids.h"
#include "toolchain/sem_ir/class.h"
#include "toolchain/sem_ir/function.h"
#include "toolchain/sem_ir/ids.h"
#include "toolchain/sem_ir/inst.h"
@@ -48,128 +49,6 @@ auto HandleParseNode(Context& context, Parse::ClassIntroducerId node_id)
return true;
}
// Tries to merge new_class into prev_class_id. Since new_class 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 class.
// Otherwise, returns false. Prints a diagnostic when appropriate.
static auto MergeClassRedecl(Context& context, Parse::AnyClassDeclId node_id,
SemIR::Class& new_class, bool new_is_definition,
SemIR::ClassId prev_class_id,
SemIR::ImportIRId prev_import_ir_id) -> bool {
auto& prev_class = context.classes().Get(prev_class_id);
SemIR::LocId prev_loc_id(prev_class.latest_decl_id());
// Check the generic parameters match, if they were specified.
if (!CheckRedeclParamsMatch(context, DeclParams(new_class),
DeclParams(prev_class))) {
return false;
}
DiagnoseIfInvalidRedecl(
context, Lex::TokenKind::Class, prev_class.name_id,
RedeclInfo(new_class, node_id, new_is_definition),
RedeclInfo(prev_class, prev_loc_id, prev_class.has_definition_started()),
prev_import_ir_id);
if (new_is_definition && prev_class.has_definition_started()) {
// Don't attempt to merge multiple definitions.
return false;
}
if (new_is_definition) {
prev_class.MergeDefinition(new_class);
}
if (prev_import_ir_id.has_value() ||
(prev_class.is_extern && !new_class.is_extern)) {
prev_class.first_owning_decl_id = new_class.first_owning_decl_id;
ReplacePrevInstForMerge(context, new_class.parent_scope_id,
prev_class.name_id, new_class.first_owning_decl_id);
}
return true;
}
// Adds the name to name lookup. If there's a conflict, tries to merge. May
// update class_decl and class_info when merging.
static auto MergeOrAddName(Context& context, Parse::AnyClassDeclId node_id,
const DeclNameStack::NameContext& name_context,
SemIR::InstId class_decl_id,
SemIR::ClassDecl& class_decl,
SemIR::Class& class_info, bool is_definition,
SemIR::AccessKind access_kind) -> void {
SemIR::ScopeLookupResult lookup_result =
context.decl_name_stack().LookupOrAddName(name_context, class_decl_id,
access_kind);
if (lookup_result.is_poisoned()) {
// This is a declaration of a poisoned name.
DiagnosePoisonedName(context, name_context.name_id_for_new_inst(),
lookup_result.poisoning_loc_id(), name_context.loc_id);
return;
}
if (!lookup_result.is_found()) {
return;
}
SemIR::InstId prev_id = lookup_result.target_inst_id();
auto prev_class_id = SemIR::ClassId::None;
auto prev_import_ir_id = SemIR::ImportIRId::None;
auto prev = context.insts().Get(prev_id);
CARBON_KIND_SWITCH(prev) {
case CARBON_KIND(SemIR::ClassDecl class_decl): {
prev_class_id = class_decl.class_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::ClassDecl>(import_ir_inst.inst_id())) {
break;
}
// Use the constant value to get the ID.
auto decl_value = context.insts().Get(
context.constant_values().GetConstantInstId(prev_id));
if (auto class_type = decl_value.TryAs<SemIR::ClassType>()) {
prev_class_id = class_type->class_id;
prev_import_ir_id = import_ir_inst.ir_id();
} else if (auto generic_class_type =
context.types().TryGetAs<SemIR::GenericClassType>(
decl_value.type_id())) {
prev_class_id = generic_class_type->class_id;
prev_import_ir_id = import_ir_inst.ir_id();
}
break;
}
default:
break;
}
if (!prev_class_id.has_value()) {
// This is a redeclaration of something other than a class.
DiagnoseDuplicateName(context, name_context.name_id, name_context.loc_id,
SemIR::LocId(prev_id));
return;
}
// TODO: Fix `extern` logic. It doesn't work correctly, but doesn't seem worth
// ripping out because existing code may incrementally help.
if (MergeClassRedecl(context, node_id, class_info, is_definition,
prev_class_id, prev_import_ir_id)) {
// When merging, use the existing entity rather than adding a new one.
class_decl.class_id = prev_class_id;
class_decl.type_id = prev.type_id();
// TODO: Validate that the redeclaration doesn't set an access modifier.
}
}
static auto BuildClassDecl(Context& context, Parse::AnyClassDeclId node_id,
bool is_definition)
-> std::tuple<SemIR::ClassId, SemIR::InstId> {
@@ -223,9 +102,13 @@ static auto BuildClassDecl(Context& context, Parse::AnyClassDeclId node_id,
DiagnoseIfGenericMissingExplicitParameters(context, class_info);
MergeOrAddName(context, node_id, name_context, class_decl_id, class_decl,
class_info, is_definition,
introducer.modifier_set.GetAccessKind());
SemIR::ScopeLookupResult lookup_result =
context.decl_name_stack().LookupOrAddName(
name_context, class_decl_id, introducer.modifier_set.GetAccessKind());
TryMergeRedecl(context, name_context, lookup_result,
MergeRedeclEntityInfo<SemIR::Class>{
.new_entity_decl = class_decl, .new_entity = class_info},
is_definition);
// Create a new class if this isn't a valid redeclaration.
bool is_new_class = !class_decl.class_id.has_value();