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Reapply "[clang] Fix sema on ObjCLifetime conversion (#178524)" (#180817)

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Clang can't handle objc lifetime correctly when casting We reuse the
approach similar to lifetime: First remove it before the conversion,
then add it back.

Add a test

Fixes https://github.com/llvm/llvm-project/issues/177478
This commit is contained in:
Peter Rong 2026-02-13 12:27:20 -08:00 committed by GitHub
parent 8cd31aa2c6
commit 742af32b67
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4 changed files with 119 additions and 1 deletions
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1
clang/docs/ReleaseNotes.rst
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@ -296,6 +296,7 @@ Miscellaneous Clang Crashes Fixed
generic lambda. (#GH172289)
- Fixed a crash in C++ overload resolution with ``_Atomic``-qualified argument types. (#GH170433)
- Fixed an assertion when diagnosing address-space qualified ``new``/``delete`` in language-defined address spaces such as OpenCL ``__local``. (#GH178319)
- Fixed an assertion failure in ObjC++ ARC when binding a rvalue reference to reference with different lifetimes (#GH178524)
OpenACC Specific Changes
------------------------

11
clang/lib/Sema/SemaInit.cpp
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@ -5651,7 +5651,16 @@ static void TryReferenceInitializationCore(Sema &S,
T1QualsIgnoreAS.removeAddressSpace();
T2QualsIgnoreAS.removeAddressSpace();
}
QualType cv1T4 = S.Context.getQualifiedType(cv2T2, T1QualsIgnoreAS);
// Strip the existing ObjC lifetime qualifier from cv2T2 before combining
// with T1's qualifiers.
QualType T2ForQualConv = cv2T2;
if (T1Quals.getObjCLifetime() != T2Quals.getObjCLifetime()) {
Qualifiers T2BaseQuals =
T2ForQualConv.getQualifiers().withoutObjCLifetime();
T2ForQualConv = S.Context.getQualifiedType(
T2ForQualConv.getUnqualifiedType(), T2BaseQuals);
}
QualType cv1T4 = S.Context.getQualifiedType(T2ForQualConv, T1QualsIgnoreAS);
if (T1QualsIgnoreAS != T2QualsIgnoreAS)
Sequence.AddQualificationConversionStep(cv1T4, ValueKind);
Sequence.AddReferenceBindingStep(cv1T4, ValueKind == VK_PRValue);

69
clang/test/CodeGenObjCXX/arc-lifetime-rvalue-ref-binding.mm Normal file
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@ -0,0 +1,69 @@
// RUN: %clang_cc1 -std=c++17 -triple x86_64-apple-darwin10 -emit-llvm -fobjc-arc -O0 -disable-llvm-passes -o - %s | FileCheck %s
// Test for correct IR generation when binding ObjC ARC __strong rvalues
// to const __autoreleasing references. Previously, this caused an assertion
// failure in Qualifiers::addConsistentQualifiers.
// The const id& parameter has implicit __autoreleasing lifetime.
void take(const id&);
// CHECK-LABEL: define{{.*}} void @_Z19test_rvalue_bindingv()
// CHECK: [[OBJ:%.*]] = alloca ptr, align 8
// CHECK: store ptr null, ptr [[OBJ]], align 8
// CHECK: call void @_Z4takeRU15__autoreleasingKP11objc_object(ptr noundef nonnull align 8 dereferenceable(8) [[OBJ]])
// CHECK: call void @llvm.objc.storeStrong(ptr [[OBJ]], ptr null)
// CHECK: ret void
void test_rvalue_binding() {
id obj = nullptr;
take(static_cast<id&&>(obj));
}
// CHECK-LABEL: define{{.*}} void @_Z19test_lvalue_bindingv()
// CHECK: [[OBJ:%.*]] = alloca ptr, align 8
// CHECK: store ptr null, ptr [[OBJ]], align 8
// CHECK: call void @_Z4takeRU15__autoreleasingKP11objc_object(ptr noundef nonnull align 8 dereferenceable(8) [[OBJ]])
// CHECK: call void @llvm.objc.storeStrong(ptr [[OBJ]], ptr null)
// CHECK: ret void
void test_lvalue_binding() {
id obj = nullptr;
take(obj);
}
// Test with fold expressions and perfect forwarding (original crash case).
template <typename... Args>
void call(Args... args) {
(take(static_cast<Args&&>(args)), ...);
}
// CHECK-LABEL: define{{.*}} void @_Z20test_fold_expressionv()
// CHECK: call void @_Z4callIJU8__strongP11objc_objectEEvDpT_(ptr noundef null)
void test_fold_expression() {
call<id>(nullptr);
}
// CHECK-LABEL: define{{.*}} void @_Z4callIJU8__strongP11objc_objectEEvDpT_(ptr noundef %args)
// CHECK: [[ARGS_ADDR:%.*]] = alloca ptr, align 8
// CHECK: store ptr null, ptr [[ARGS_ADDR]], align 8
// CHECK: call void @llvm.objc.storeStrong(ptr [[ARGS_ADDR]], ptr %args)
// CHECK: call void @_Z4takeRU15__autoreleasingKP11objc_object(ptr noundef nonnull align 8 dereferenceable(8) [[ARGS_ADDR]])
// CHECK: call void @llvm.objc.storeStrong(ptr [[ARGS_ADDR]], ptr null)
// CHECK: ret void
// Test that binding a prvalue to an __autoreleasing rvalue reference emits
// retain+autorelease (not retain+release), per ARC semantics for __autoreleasing.
// CHECK-LABEL: define{{.*}} void @_Z32test_autoreleasing_rvalue_ref_prP11objc_object(ptr noundef %a)
// CHECK: [[A_ADDR:%.*]] = alloca ptr, align 8
// CHECK: [[R:%.*]] = alloca ptr, align 8
// CHECK: [[REF_TMP:%.*]] = alloca ptr, align 8
// CHECK: store ptr null, ptr [[A_ADDR]], align 8
// CHECK: call void @llvm.objc.storeStrong(ptr [[A_ADDR]], ptr %a)
// CHECK: [[LOAD:%.*]] = load ptr, ptr [[A_ADDR]], align 8
// CHECK: [[RETAINED:%.*]] = call ptr @llvm.objc.retain(ptr [[LOAD]])
// CHECK: [[AUTORELEASED:%.*]] = call ptr @llvm.objc.autorelease(ptr [[RETAINED]])
// CHECK: store ptr [[AUTORELEASED]], ptr [[REF_TMP]], align 8
// CHECK: store ptr [[REF_TMP]], ptr [[R]], align 8
// CHECK: call void @llvm.objc.storeStrong(ptr [[A_ADDR]], ptr null)
// CHECK: ret void
void test_autoreleasing_rvalue_ref_pr(id a) {
id __autoreleasing && r = id{a};
}

39
clang/test/SemaObjCXX/arc-lifetime-rvalue-ref-binding.mm Normal file
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@ -0,0 +1,39 @@
// RUN: %clang_cc1 -std=c++17 -fsyntax-only -fobjc-arc -verify %s
// RUN: %clang_cc1 -std=c++17 -fobjc-arc -ast-dump %s 2>&1 | FileCheck %s
// expected-no-diagnostics
// Test for binding ObjC ARC __strong rvalues to const __autoreleasing references.
// This previously caused an assertion failure in Qualifiers::addConsistentQualifiers
// when the compiler attempted to add conflicting ObjC lifetime qualifiers.
// The const id& parameter has implicit __autoreleasing lifetime.
void take(const id&);
// CHECK-LABEL: FunctionDecl {{.*}} test_rvalue_binding
// CHECK: CallExpr
// CHECK: ImplicitCastExpr {{.*}} 'const __autoreleasing id' xvalue <NoOp>
// CHECK-NEXT: CXXStaticCastExpr {{.*}} '__strong id' xvalue static_cast<__strong id &&> <NoOp>
void test_rvalue_binding() {
id obj = nullptr;
take(static_cast<id&&>(obj));
}
// CHECK-LABEL: FunctionDecl {{.*}} test_lvalue_binding
// CHECK: CallExpr
// CHECK: ImplicitCastExpr {{.*}} 'const __autoreleasing id' lvalue <NoOp>
// CHECK-NEXT: DeclRefExpr {{.*}} '__strong id' lvalue
void test_lvalue_binding() {
id obj = nullptr;
take(obj);
}
// Test with fold expressions and perfect forwarding (original crash case).
template <typename... Args>
void call(Args... args) {
(take(static_cast<Args&&>(args)), ...);
}
// CHECK-LABEL: FunctionDecl {{.*}} test_fold_expression
void test_fold_expression() {
call<id>(nullptr);
}