Author: Haojian Wu Date: 2024-07-02T15:21:06+02:00 New Revision: c3079ffcd34e8ee2faaf7576a69a49acc1a3653f
URL: https://github.com/llvm/llvm-project/commit/c3079ffcd34e8ee2faaf7576a69a49acc1a3653f DIFF: https://github.com/llvm/llvm-project/commit/c3079ffcd34e8ee2faaf7576a69a49acc1a3653f.diff LOG: [clang] Don't emit the warn_dangling_lifetime_pointer diagnostic for the assignment case. (#97408) The `lifetime_pointer` case is handled before the assignment case. In scenarios where we have the `gsl::Pointer` attribute, we may emit the `-Wdangling-gsl` warning for assignment cases. This means we cannot use `-Wno-dangling-assignment` to suppress the newly-added warning, this patch fixes it. Added: Modified: clang/lib/Sema/CheckExprLifetime.cpp clang/test/SemaCXX/warn-dangling-local.cpp Removed: ################################################################################ diff --git a/clang/lib/Sema/CheckExprLifetime.cpp b/clang/lib/Sema/CheckExprLifetime.cpp index fea0239f7bc36..2f9ef28da2c3e 100644 --- a/clang/lib/Sema/CheckExprLifetime.cpp +++ b/clang/lib/Sema/CheckExprLifetime.cpp @@ -1008,7 +1008,19 @@ static void checkExprLifetimeImpl(Sema &SemaRef, return true; } } + if (AEntity) { + if (!MTE) + return false; + assert(shouldLifetimeExtendThroughPath(Path) == + PathLifetimeKind::NoExtend && + "No lifetime extension for assignments"); + if (!pathContainsInit(Path)) + SemaRef.Diag(DiagLoc, diag::warn_dangling_pointer_assignment) + << AEntity->LHS << DiagRange; + return false; + } + assert(InitEntity && "only for initialization"); switch (LK) { case LK_FullExpression: llvm_unreachable("already handled this"); @@ -1031,8 +1043,6 @@ static void checkExprLifetimeImpl(Sema &SemaRef, switch (shouldLifetimeExtendThroughPath(Path)) { case PathLifetimeKind::Extend: - assert(InitEntity && "Lifetime extension should happen only for " - "initialization and not assignment"); // Update the storage duration of the materialized temporary. // FIXME: Rebuild the expression instead of mutating it. MTE->setExtendingDecl(ExtendingEntity->getDecl(), @@ -1041,8 +1051,6 @@ static void checkExprLifetimeImpl(Sema &SemaRef, return true; case PathLifetimeKind::ShouldExtend: - assert(InitEntity && "Lifetime extension should happen only for " - "initialization and not assignment"); // We're supposed to lifetime-extend the temporary along this path (per // the resolution of DR1815), but we don't support that yet. // @@ -1060,23 +1068,16 @@ static void checkExprLifetimeImpl(Sema &SemaRef, if (pathContainsInit(Path)) return false; - if (InitEntity) { - SemaRef.Diag(DiagLoc, diag::warn_dangling_variable) - << RK << !InitEntity->getParent() - << ExtendingEntity->getDecl()->isImplicit() - << ExtendingEntity->getDecl() << Init->isGLValue() << DiagRange; - } else { - SemaRef.Diag(DiagLoc, diag::warn_dangling_pointer_assignment) - << AEntity->LHS << DiagRange; - } + SemaRef.Diag(DiagLoc, diag::warn_dangling_variable) + << RK << !InitEntity->getParent() + << ExtendingEntity->getDecl()->isImplicit() + << ExtendingEntity->getDecl() << Init->isGLValue() << DiagRange; break; } break; } case LK_MemInitializer: { - assert(InitEntity && "Expect only on initializing the entity"); - if (MTE) { // Under C++ DR1696, if a mem-initializer (or a default member // initializer used by the absence of one) would lifetime-extend a @@ -1151,7 +1152,6 @@ static void checkExprLifetimeImpl(Sema &SemaRef, } case LK_New: - assert(InitEntity && "Expect only on initializing the entity"); if (isa<MaterializeTemporaryExpr>(L)) { if (IsGslPtrInitWithGslTempOwner) SemaRef.Diag(DiagLoc, diag::warn_dangling_lifetime_pointer) @@ -1169,7 +1169,6 @@ static void checkExprLifetimeImpl(Sema &SemaRef, case LK_Return: case LK_StmtExprResult: - assert(InitEntity && "Expect only on initializing the entity"); if (auto *DRE = dyn_cast<DeclRefExpr>(L)) { // We can't determine if the local variable outlives the statement // expression. diff --git a/clang/test/SemaCXX/warn-dangling-local.cpp b/clang/test/SemaCXX/warn-dangling-local.cpp index a946b8a241a38..2808a4c01f88d 100644 --- a/clang/test/SemaCXX/warn-dangling-local.cpp +++ b/clang/test/SemaCXX/warn-dangling-local.cpp @@ -26,3 +26,14 @@ void g() { const int a[] = {a[0]}; const int b[] = {a[0]}; } + +namespace std { +// std::basic_string has a hard-coded gsl::owner attr. +struct basic_string { + const char* c_str(); +}; +} // namespace std +void test(const char* a) { + // verify we're emitting the `-Wdangling-assignment` warning. + a = std::basic_string().c_str(); // expected-warning {{object backing the pointer a will be destroyed at the end of the full-expression}} +} _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
