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Destroy locals at the end of blocks, not only on return (#7448)

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Destroy local variables and temporaries at each `}`, and when branching
with `break` and `continue`. In `for` statements, destroy loop variables
along with anything created within the loop at the end of each loop
iteration, and destroy the cursor and range object when the loop
terminates.

Assisted-by: Gemini via Antigravity

---------

Co-authored-by: Geoff Romer <gromer@google.com>
This commit is contained in:
Richard Smith
2026-07-14 00:59:22 +00:00
committed by GitHub
co-authored by Geoff Romer
parent 8bae79f44a
commit 6e62a7d4a2
29 changed files with 1803 additions and 266 deletions
Download Patch File Download Diff File Expand all files Collapse all files
toolchain/check/scope_stack.cpp
+50 -14
View File
@@ -9,6 +9,7 @@
#include "common/check.h"
#include "common/find.h"
#include "toolchain/check/context.h"
#include "toolchain/check/control_flow.h"
#include "toolchain/check/unused.h"
#include "toolchain/sem_ir/ids.h"
@@ -51,6 +52,7 @@ auto ScopeStack::VerifyNextCompileTimeBindIndex(llvm::StringLiteral label,
auto ScopeStack::Push(SemIR::InstId scope_inst_id, SemIR::NameScopeId scope_id,
SemIR::SpecificId specific_id,
CleanupScopeKind cleanup_scope_kind,
bool lexical_lookup_has_load_error) -> void {
// If this scope doesn't have a specific of its own, it lives in the enclosing
// scope's specific, if any.
@@ -68,7 +70,8 @@ auto ScopeStack::Push(SemIR::InstId scope_inst_id, SemIR::NameScopeId scope_id,
.next_compile_time_bind_index = SemIR::CompileTimeBindIndex(
compile_time_binding_stack_.all_values_size()),
.lexical_lookup_has_load_error =
LexicalLookupHasLoadError() || lexical_lookup_has_load_error});
LexicalLookupHasLoadError() || lexical_lookup_has_load_error,
.cleanup_scope_kind = cleanup_scope_kind});
if (scope_stack_.back().is_lexical_scope()) {
// For lexical lookups, unqualified lookup doesn't know how to find the
// associated specific, so if we start adding lexical scopes associated with
@@ -93,11 +96,15 @@ auto ScopeStack::Push(SemIR::InstId scope_inst_id, SemIR::NameScopeId scope_id,
++next_scope_index_.index;
VerifyNextCompileTimeBindIndex("Push", scope_stack_.back());
if (cleanup_scope_kind == CleanupScopeKind::Owned) {
destroy_id_stack_.PushArray();
}
}
auto ScopeStack::PushForDeclName() -> void {
Push(SemIR::InstId::None, SemIR::NameScopeId::None, SemIR::SpecificId::None,
/*lexical_lookup_has_load_error=*/false);
CleanupScopeKind::None, /*lexical_lookup_has_load_error=*/false);
MarkNestingIfInReturnScope();
}
@@ -107,13 +114,20 @@ auto ScopeStack::PushForEntity(SemIR::InstId scope_inst_id,
bool lexical_lookup_has_load_error) -> void {
CARBON_CHECK(scope_inst_id.has_value());
CARBON_DCHECK(!sem_ir().insts().Is<SemIR::FunctionDecl>(scope_inst_id));
Push(scope_inst_id, scope_id, specific_id, lexical_lookup_has_load_error);
Push(scope_inst_id, scope_id, specific_id, CleanupScopeKind::None,
lexical_lookup_has_load_error);
MarkNestingIfInReturnScope();
}
auto ScopeStack::PushForSameRegion() -> void {
auto ScopeStack::PushForSameRegion(CleanupScopeKind cleanup_scope_kind)
-> void {
if (cleanup_scope_kind == CleanupScopeKind::Inherited &&
Peek().cleanup_scope_kind == CleanupScopeKind::None) {
cleanup_scope_kind = CleanupScopeKind::None;
}
Push(SemIR::InstId::None, SemIR::NameScopeId::None, SemIR::SpecificId::None,
/*lexical_lookup_has_load_error=*/false);
cleanup_scope_kind, /*lexical_lookup_has_load_error=*/false);
}
auto ScopeStack::PushForFunctionBody(SemIR::InstId scope_inst_id) -> void {
@@ -122,10 +136,10 @@ auto ScopeStack::PushForFunctionBody(SemIR::InstId scope_inst_id) -> void {
const auto& function = sem_ir().functions().Get(function_decl.function_id);
auto self_specific = sem_ir().generics().GetSelfSpecific(function.generic_id);
Push(scope_inst_id, SemIR::NameScopeId::None, self_specific,
/*lexical_lookup_has_load_error=*/false);
CleanupScopeKind::Owned, /*lexical_lookup_has_load_error=*/false);
return_scope_stack_.push_back({.decl_id = scope_inst_id});
destroy_id_stack_.PushArray();
return_scope_stack_.push_back(
{.decl_id = scope_inst_id, .cleanup_scope_depth = cleanup_scope_depth()});
}
auto ScopeStack::Pop(bool check_unused) -> void {
@@ -148,6 +162,12 @@ auto ScopeStack::Pop(bool check_unused) -> void {
non_lexical_scope_stack_.pop_back();
}
if (scope.cleanup_scope_kind == CleanupScopeKind::Owned) {
CARBON_CHECK(destroy_id_stack_.PeekArray().empty(),
"Popping scope with cleanups");
destroy_id_stack_.PopArray();
}
if (!return_scope_stack_.empty()) {
if (scope.has_returned_var) {
CARBON_CHECK(return_scope_stack_.back().returned_var.has_value());
@@ -157,13 +177,12 @@ auto ScopeStack::Pop(bool check_unused) -> void {
if (return_scope_stack_.back().decl_id == scope.scope_inst_id) {
// Leaving the function scope.
return_scope_stack_.pop_back();
destroy_id_stack_.PopArray();
} else if (return_scope_stack_.back().nested_scope_index == scope.index) {
// Returned to a function scope from a non-function nested entity scope.
return_scope_stack_.back().nested_scope_index = ScopeIndex::None;
} else {
if (return_scope_stack_.back().nested_scope_index == scope.index) {
// Returned to a function scope from a non-function nested entity scope.
return_scope_stack_.back().nested_scope_index = ScopeIndex::None;
}
}
} else {
CARBON_CHECK(!scope.has_returned_var);
}
VerifyNextCompileTimeBindIndex("Pop", scope);
@@ -179,6 +198,21 @@ auto ScopeStack::PopTo(ScopeIndex index, bool check_unused) -> void {
PeekIndex());
}
auto ScopeStack::MergeTopScopeIntoGrandparentAndPop() -> void {
CARBON_CHECK(scope_stack_.size() >= 3);
auto& grandparent = scope_stack_[scope_stack_.size() - 3];
auto& parent = scope_stack_[scope_stack_.size() - 2];
auto& current = scope_stack_[scope_stack_.size() - 1];
CARBON_CHECK(current.num_names == 0);
CARBON_CHECK(grandparent.cleanup_scope_kind != CleanupScopeKind::None &&
parent.cleanup_scope_kind == CleanupScopeKind::Owned &&
current.cleanup_scope_kind == CleanupScopeKind::Owned);
destroy_id_stack_.MergeTopArrayIntoGrandparent();
Pop();
}
auto ScopeStack::MarkUsed(SemIR::NameId name_id, SemIR::LocId loc_id,
bool is_reachable) -> void {
auto& lexical_results = lexical_lookup_.Get(name_id);
@@ -361,6 +395,8 @@ auto ScopeStack::Suspend() -> SuspendedScope {
compile_time_binding_stack_.PopArray();
// This would be easy to support if we had a need, but currently we do not.
CARBON_CHECK(result.entry.cleanup_scope_kind == CleanupScopeKind::None,
"Should not suspend a function definition scope.");
CARBON_CHECK(!result.entry.has_returned_var,
"Should not suspend a scope with a returned var.");
return result;