https://github.com/ahatanak created
https://github.com/llvm/llvm-project/pull/144458
Allow using reinterpret_cast for conversions between indirect ARC pointers and
other pointer types.
rdar://153049268
>From 7a042947bbedce4e9bbb31b599f8132013bf8f3b Mon Sep 17 00:00:00 2001
From: Akira Hatanaka <ahatan...@apple.com>
Date: Fri, 13 Jun 2025 15:01:26 -0700
Subject: [PATCH] [Sema][ObjC] Loosen restrictions on reinterpret_cast
involving indirect ARC-managed pointers
Allow using reinterpret_cast for conversions between indirect ARC
pointers and other pointer types.
rdar://153049268
---
clang/include/clang/Sema/SemaObjC.h | 3 ++-
clang/lib/Sema/SemaCast.cpp | 11 +++++++----
clang/lib/Sema/SemaExprObjC.cpp | 14 ++++++++++----
clang/test/SemaObjCXX/arc-type-conversion.mm | 14 ++++++++++++--
4 files changed, 31 insertions(+), 11 deletions(-)
diff --git a/clang/include/clang/Sema/SemaObjC.h
b/clang/include/clang/Sema/SemaObjC.h
index b629c6d291402..ed08ff0acf89d 100644
--- a/clang/include/clang/Sema/SemaObjC.h
+++ b/clang/include/clang/Sema/SemaObjC.h
@@ -812,7 +812,8 @@ class SemaObjC : public SemaBase {
CheckedConversionKind CCK,
bool Diagnose = true,
bool DiagnoseCFAudited = false,
- BinaryOperatorKind Opc = BO_PtrMemD);
+ BinaryOperatorKind Opc = BO_PtrMemD,
+ bool IsReinterpretCast = false);
Expr *stripARCUnbridgedCast(Expr *e);
void diagnoseARCUnbridgedCast(Expr *e);
diff --git a/clang/lib/Sema/SemaCast.cpp b/clang/lib/Sema/SemaCast.cpp
index 14e16bc39eb3a..e15a43c116516 100644
--- a/clang/lib/Sema/SemaCast.cpp
+++ b/clang/lib/Sema/SemaCast.cpp
@@ -161,12 +161,14 @@ namespace {
Self.CheckCastAlign(SrcExpr.get(), DestType, OpRange);
}
- void checkObjCConversion(CheckedConversionKind CCK) {
+ void checkObjCConversion(CheckedConversionKind CCK,
+ bool IsReinterpretCast = false) {
assert(Self.getLangOpts().allowsNonTrivialObjCLifetimeQualifiers());
Expr *src = SrcExpr.get();
- if (Self.ObjC().CheckObjCConversion(OpRange, DestType, src, CCK) ==
- SemaObjC::ACR_unbridged)
+ if (Self.ObjC().CheckObjCConversion(
+ OpRange, DestType, src, CCK, true, false, BO_PtrMemD,
+ IsReinterpretCast) == SemaObjC::ACR_unbridged)
IsARCUnbridgedCast = true;
SrcExpr = src;
}
@@ -1263,7 +1265,8 @@ void CastOperation::CheckReinterpretCast() {
if (isValidCast(tcr)) {
if (Self.getLangOpts().allowsNonTrivialObjCLifetimeQualifiers())
- checkObjCConversion(CheckedConversionKind::OtherCast);
+ checkObjCConversion(CheckedConversionKind::OtherCast,
+ /*IsReinterpretCast=*/true);
DiagnoseReinterpretUpDownCast(Self, SrcExpr.get(), DestType, OpRange);
if (unsigned DiagID = checkCastFunctionType(Self, SrcExpr, DestType))
diff --git a/clang/lib/Sema/SemaExprObjC.cpp b/clang/lib/Sema/SemaExprObjC.cpp
index 3505d9f38d23c..59a2e660364de 100644
--- a/clang/lib/Sema/SemaExprObjC.cpp
+++ b/clang/lib/Sema/SemaExprObjC.cpp
@@ -4390,7 +4390,7 @@ SemaObjC::ARCConversionResult
SemaObjC::CheckObjCConversion(SourceRange castRange, QualType castType,
Expr *&castExpr, CheckedConversionKind CCK,
bool Diagnose, bool DiagnoseCFAudited,
- BinaryOperatorKind Opc) {
+ BinaryOperatorKind Opc, bool IsReinterpretCast) {
ASTContext &Context = getASTContext();
QualType castExprType = castExpr->getType();
@@ -4450,13 +4450,19 @@ SemaObjC::CheckObjCConversion(SourceRange castRange,
QualType castType,
// must be explicit.
// Allow conversions between pointers to lifetime types and coreFoundation
// pointers too, but only when the conversions are explicit.
+ // Allow conversions requested with a reinterpret_cast that converts an
+ // expression of type T* to type U*.
if (exprACTC == ACTC_indirectRetainable &&
(castACTC == ACTC_voidPtr ||
- (castACTC == ACTC_coreFoundation && SemaRef.isCast(CCK))))
+ (castACTC == ACTC_coreFoundation && SemaRef.isCast(CCK)) ||
+ (IsReinterpretCast && (effCastType->isPointerType() ||
+ effCastType->isObjCObjectPointerType()))))
return ACR_okay;
if (castACTC == ACTC_indirectRetainable &&
- (exprACTC == ACTC_voidPtr || exprACTC == ACTC_coreFoundation) &&
- SemaRef.isCast(CCK))
+ (((exprACTC == ACTC_voidPtr || exprACTC == ACTC_coreFoundation) &&
+ SemaRef.isCast(CCK)) ||
+ (IsReinterpretCast && (castExprType->isPointerType() ||
+ castExprType->isObjCObjectPointerType()))))
return ACR_okay;
switch (ARCCastChecker(Context, exprACTC, castACTC, false).Visit(castExpr)) {
diff --git a/clang/test/SemaObjCXX/arc-type-conversion.mm
b/clang/test/SemaObjCXX/arc-type-conversion.mm
index 64cfd02ec18c0..2b44624121504 100644
--- a/clang/test/SemaObjCXX/arc-type-conversion.mm
+++ b/clang/test/SemaObjCXX/arc-type-conversion.mm
@@ -1,5 +1,7 @@
// RUN: %clang_cc1 -fobjc-runtime-has-weak -fsyntax-only -fobjc-arc -verify
-fblocks %s
+@class NSString;
+
void * cvt(id arg) // expected-note{{candidate function not viable: cannot
convert argument of incomplete type 'void *' to '__strong id'}}
{
void* voidp_val;
@@ -72,6 +74,16 @@ void test_reinterpret_cast(__strong id *sip, __weak id *wip,
(void)reinterpret_cast<__weak id *>(cwip); //
expected-error{{reinterpret_cast from '__weak id const *' to '__weak id *'
casts away qualifiers}}
(void)reinterpret_cast<__weak id *>(csip); //
expected-error{{reinterpret_cast from '__strong id const *' to '__weak id *'
casts away qualifiers}}
(void)reinterpret_cast<__strong id *>(cwip); //
expected-error{{reinterpret_cast from '__weak id const *' to '__strong id *'
casts away qualifiers}}
+
+ auto *p0 = reinterpret_cast<unsigned long *>(sip);
+ (void)reinterpret_cast<__strong id *>(p0);
+ auto *p1 = reinterpret_cast<__weak NSString *>(sip);
+ (void)reinterpret_cast<__strong id *>(p1);
+ (void)reinterpret_cast<unsigned long *>(csip); // expected-error
{{reinterpret_cast from '__strong id const *' to 'unsigned long *' casts away
qualifiers}}
+ const unsigned long *p2 = nullptr;
+ (void)reinterpret_cast<__strong id *>(p2); // expected-error
{{reinterpret_cast from 'const unsigned long *' to '__strong id *' casts away
qualifiers}}
+ auto ul = reinterpret_cast<unsigned long>(sip);
+ (void)reinterpret_cast<__strong id *>(ul); // expected-error {{cast of
'unsigned long' to '__strong id *' is disallowed with ARC}}
}
void test_cstyle_cast(__strong id *sip, __weak id *wip,
@@ -194,8 +206,6 @@ void from_void(void *vp) {
typedef void (^Block_strong)() __strong;
typedef void (^Block_autoreleasing)() __autoreleasing;
-@class NSString;
-
void ownership_transfer_in_cast(void *vp, Block *pblk) {
__strong NSString **sip2 = static_cast<NSString **>(static_cast<__strong id
*>(vp));
__strong NSString **&si2pref = static_cast<NSString **&>(sip2);
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