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Silence spurious -Wnontrivial-memcall warnings in C mode (#137429)

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clang currently issues a warning when memset is used on a struct that
contains an address-discriminated pointer field, even though this is
entirely valid behavior.

For example:

```
struct S {
  int * __ptrauth(1, 1, 100) p;
} s;

memset(&s, 0, sizeof(struct S));
```

Only allow the warning to be emitted in C++ mode to silence the warning.

rdar://142495870
This commit is contained in:
Akira Hatanaka 2025-04-29 18:37:57 -07:00 committed by GitHub
parent a01a5b82dc
commit 6bb4ce0f6f
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GPG Key ID: B5690EEEBB952194
2 changed files with 65 additions and 5 deletions
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10
clang/lib/Sema/SemaChecking.cpp
View File

@ -9735,9 +9735,9 @@ void Sema::CheckMemaccessArguments(const CallExpr *Call,
// completed later. GCC does not diagnose such code, but we may want to
// consider diagnosing it in the future, perhaps under a different, but
// related, diagnostic group.
bool MayBeTriviallyCopyableCXXRecord =
RT->isIncompleteType() ||
RT->desugar().isTriviallyCopyableType(Context);
bool NonTriviallyCopyableCXXRecord =
getLangOpts().CPlusPlus && !RT->isIncompleteType() &&
!RT->desugar().isTriviallyCopyableType(Context);
if ((BId == Builtin::BImemset || BId == Builtin::BIbzero) &&
RT->getDecl()->isNonTrivialToPrimitiveDefaultInitialize()) {
@ -9746,7 +9746,7 @@ void Sema::CheckMemaccessArguments(const CallExpr *Call,
<< ArgIdx << FnName << PointeeTy << 0);
SearchNonTrivialToInitializeField::diag(PointeeTy, Dest, *this);
} else if ((BId == Builtin::BImemset || BId == Builtin::BIbzero) &&
!MayBeTriviallyCopyableCXXRecord && ArgIdx == 0) {
NonTriviallyCopyableCXXRecord && ArgIdx == 0) {
// FIXME: Limiting this warning to dest argument until we decide
// whether it's valid for source argument too.
DiagRuntimeBehavior(Dest->getExprLoc(), Dest,
@ -9759,7 +9759,7 @@ void Sema::CheckMemaccessArguments(const CallExpr *Call,
<< ArgIdx << FnName << PointeeTy << 1);
SearchNonTrivialToCopyField::diag(PointeeTy, Dest, *this);
} else if ((BId == Builtin::BImemcpy || BId == Builtin::BImemmove) &&
!MayBeTriviallyCopyableCXXRecord && ArgIdx == 0) {
NonTriviallyCopyableCXXRecord && ArgIdx == 0) {
// FIXME: Limiting this warning to dest argument until we decide
// whether it's valid for source argument too.
DiagRuntimeBehavior(Dest->getExprLoc(), Dest,

60
clang/test/Sema/warn-nontrivial-struct-memaccess-ptrauth.c Normal file
View File

@ -0,0 +1,60 @@
// RUN: %clang_cc1 -triple arm64-apple-ios -fptrauth-calls -fptrauth-intrinsics -fsyntax-only -verify=c,expected %s
// RUN: %clang_cc1 -triple aarch64-linux-gnu -fptrauth-calls -fptrauth-intrinsics -fsyntax-only -verify=c,expected %s
// RUN: %clang_cc1 -triple arm64-apple-ios -fptrauth-calls -fptrauth-intrinsics -fsyntax-only -x c++ -verify=cxx,expected %s
// RUN: %clang_cc1 -triple aarch64-linux-gnu -fptrauth-calls -fptrauth-intrinsics -fsyntax-only -x c++ -verify=cxx,expected %s
#if defined __cplusplus
extern "C" {
#endif
void *memset(void *, int, __SIZE_TYPE__);
void bzero(void *, __SIZE_TYPE__);
void *memcpy(void *, const void *, __SIZE_TYPE__);
void *memmove(void *, const void *, __SIZE_TYPE__);
#if defined __cplusplus
}
#endif
#define AQ __ptrauth(1,1,50)
#define IQ __ptrauth(1,0,50)
struct PtrAuthTrivial {
int f0;
int * IQ f1;
};
struct PtrAuthNonTrivial0 {
int f0;
int * AQ f1; // c-note 2 {{non-trivial to copy}}
int f2;
};
struct PtrAuthNonTrivial1 {
int * AQ f0; // c-note 2 {{non-trivial to copy}}
int f1;
struct PtrAuthNonTrivial0 f2;
};
void testPtrAuthTrivial(struct PtrAuthTrivial *d, struct PtrAuthTrivial *s) {
memset(d, 0, sizeof(struct PtrAuthTrivial));
memset(d, 1, sizeof(struct PtrAuthTrivial));
bzero(d, sizeof(struct PtrAuthTrivial));
memcpy(d, s, sizeof(struct PtrAuthTrivial));
memmove(d, s, sizeof(struct PtrAuthTrivial));
}
void testPtrAuthNonTrivial1(struct PtrAuthNonTrivial1 *d,
struct PtrAuthNonTrivial1 *s) {
memset(d, 0, sizeof(struct PtrAuthNonTrivial1)); // cxx-warning {{is a pointer to non-trivially copyable type 'struct PtrAuthNonTrivial1'}} // cxx-note {{explicitly cast the pointer to silence}}
memset(d, 1, sizeof(struct PtrAuthNonTrivial1)); // cxx-warning {{is a pointer to non-trivially copyable type 'struct PtrAuthNonTrivial1'}} // cxx-note {{explicitly cast the pointer to silence}}
bzero(d, sizeof(struct PtrAuthNonTrivial1)); // cxx-warning {{is a pointer to non-trivially copyable type 'struct PtrAuthNonTrivial1'}} // cxx-note {{explicitly cast the pointer to silence}}
memcpy(d, s, sizeof(struct PtrAuthNonTrivial1));
// c-warning@-1 {{that is not trivial to primitive-copy}}
// cxx-warning@-2 {{is a pointer to non-trivially copyable type 'struct PtrAuthNonTrivial1'}}
// expected-note@-3 {{explicitly cast the pointer to silence}}
memmove(d, s, sizeof(struct PtrAuthNonTrivial1));
// c-warning@-1 {{that is not trivial to primitive-copy}}
// cxx-warning@-2 {{is a pointer to non-trivially copyable type 'struct PtrAuthNonTrivial1'}}
// expected-note@-3 {{explicitly cast the pointer to silence}}
}