carbon-language/carbon-lang
1
0
Fork 0
mirror of https://github.com/carbon-language/carbon-lang.git synced 2026-10-06 07:24:42 +01:00
Code Issues Packages Projects Releases 10 Wiki Activity

Import non-const rvalue references as var parameters. (#7125)

Browse Source 
When importing a C++ function with an rvalue reference parameter, we
previously produced a Carbon value parameter. This would lead to the
toolchain believing it could pass the address of a non-expiring object
to the function, which would lead to a use-after-move.

Instead, we now map non-const rvalue reference parameters to Carbon
`var` parameters. This forces the object passed into C++ to be unique
and owned by the call. While that's not an exact match for C++ rvalue
reference parameters, given that it provides "always move" not
"conditionally move", it's the closest match we have at the moment.
This commit is contained in:
Richard Smith
2026-04-29 00:28:00 +00:00
committed by GitHub
parent ab0aff91b8
commit 0124aae041
23 changed files with 412 additions and 411 deletions
Download Patch File Download Diff File Expand all files Collapse all files
toolchain/check/pattern.cpp
+41 -16
View File
@@ -9,6 +9,7 @@
#include "toolchain/check/inst.h"
#include "toolchain/check/return.h"
#include "toolchain/check/type.h"
#include "toolchain/sem_ir/inst.h"
namespace Carbon::Check {
@@ -202,27 +203,51 @@ auto AddPatternVarStorage(Context& context, SemIR::InstBlockId pattern_block_id,
auto AddParamPattern(Context& context, SemIR::LocId loc_id,
SemIR::NameId name_id,
SemIR::ExprRegionId type_expr_region_id,
SemIR::TypeId type_id, bool is_ref) -> SemIR::InstId {
auto pattern_type_id = GetPatternType(context, type_id);
const auto& param_pattern_kind =
is_ref ? SemIR::RefParamPattern::Kind : SemIR::ValueParamPattern::Kind;
auto pattern_id = AddInst(
context, SemIR::LocIdAndInst::RuntimeVerified(
context.sem_ir(), loc_id,
SemIR::AnyLeafParamPattern{.kind = param_pattern_kind,
.type_id = pattern_type_id,
.pretty_name_id = name_id}));
SemIR::TypeId type_id, ParamPatternKind kind)
-> SemIR::InstId {
auto param_pattern_kind = [kind]() -> SemIR::InstKind {
switch (kind) {
case ParamPatternKind::Value:
return SemIR::ValueParamPattern::Kind;
case ParamPatternKind::Ref:
return SemIR::RefParamPattern::Kind;
case ParamPatternKind::Var:
return SemIR::VarParamPattern::Kind;
}
}();
auto entity_name_id = AddBindingEntityName(context, name_id,
/*form_id=*/SemIR::InstId::None,
/*is_unused=*/false,
/*phase=*/BindingPhase::Runtime);
return AddBindingPattern(context, loc_id, type_expr_region_id,
{.kind = SemIR::WrapperBindingPattern::Kind,
.type_id = GetPatternType(context, type_id),
.entity_name_id = entity_name_id,
.subpattern_id = pattern_id})
.pattern_id;
auto pattern_type_id = GetPatternType(context, type_id);
if (kind == ParamPatternKind::Var) {
auto pattern_id = AddBindingPattern(context, loc_id, type_expr_region_id,
{.kind = SemIR::RefBindingPattern::Kind,
.type_id = pattern_type_id,
.entity_name_id = entity_name_id,
.subpattern_id = SemIR::InstId::None});
return AddInst(context, SemIR::LocIdAndInst::RuntimeVerified(
context.sem_ir(), loc_id,
SemIR::VarParamPattern{
.type_id = pattern_type_id,
.subpattern_id = pattern_id.pattern_id}));
} else {
auto pattern_id = AddInst(
context, SemIR::LocIdAndInst::RuntimeVerified(
context.sem_ir(), loc_id,
SemIR::AnyLeafParamPattern{.kind = param_pattern_kind,
.type_id = pattern_type_id,
.pretty_name_id = name_id}));
return AddBindingPattern(context, loc_id, type_expr_region_id,
{.kind = SemIR::WrapperBindingPattern::Kind,
.type_id = GetPatternType(context, type_id),
.entity_name_id = entity_name_id,
.subpattern_id = pattern_id})
.pattern_id;
}
}
} // namespace Carbon::Check