https://github.com/AaronBallman created
https://github.com/llvm/llvm-project/pull/135013
We were passing the address of a local variable to a call to Diag() which then
tried to use the object after its lifetime ended, resulting in crashes. We no
longer pass the temporary object any longer.
Fixes #26612
>From 99190952174f334642ec237596969f9b0c846411 Mon Sep 17 00:00:00 2001
From: Aaron Ballman <aa...@aaronballman.com>
Date: Wed, 9 Apr 2025 09:51:49 -0400
Subject: [PATCH] Fix crash with align_value diagnostic reporting
We were passing the address of a local variable to a call to Diag()
which then tried to use the object after its lifetime ended, resulting
in crashes. We no longer pass the temporary object any longer.
Fixes #26612
---
clang/docs/ReleaseNotes.rst | 4 ++++
clang/lib/Sema/SemaDeclAttr.cpp | 3 +--
clang/test/SemaCXX/align_value.cpp | 14 ++++++++++++++
3 files changed, 19 insertions(+), 2 deletions(-)
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 5b702b56038f7..cd16641c25ed8 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -386,6 +386,10 @@ Bug Fixes to Attribute Support
or too few attribute argument indicies for the specified callback function.
(#GH47451)
+- No longer crashing on ``__attribute__((align_value(N)))`` during template
+ instantiation when the function parameter type is not a pointer or reference.
+ (#GH26612)
+
Bug Fixes to C++ Support
^^^^^^^^^^^^^^^^^^^^^^^^
diff --git a/clang/lib/Sema/SemaDeclAttr.cpp b/clang/lib/Sema/SemaDeclAttr.cpp
index d76afe9d6464d..b3c0367ed51b2 100644
--- a/clang/lib/Sema/SemaDeclAttr.cpp
+++ b/clang/lib/Sema/SemaDeclAttr.cpp
@@ -4383,7 +4383,6 @@ static void handleAlignValueAttr(Sema &S, Decl *D, const
ParsedAttr &AL) {
}
void Sema::AddAlignValueAttr(Decl *D, const AttributeCommonInfo &CI, Expr *E) {
- AlignValueAttr TmpAttr(Context, CI, E);
SourceLocation AttrLoc = CI.getLoc();
QualType T;
@@ -4397,7 +4396,7 @@ void Sema::AddAlignValueAttr(Decl *D, const
AttributeCommonInfo &CI, Expr *E) {
if (!T->isDependentType() && !T->isAnyPointerType() &&
!T->isReferenceType() && !T->isMemberPointerType()) {
Diag(AttrLoc, diag::warn_attribute_pointer_or_reference_only)
- << &TmpAttr << T << D->getSourceRange();
+ << CI << T << D->getSourceRange();
return;
}
diff --git a/clang/test/SemaCXX/align_value.cpp
b/clang/test/SemaCXX/align_value.cpp
index 519868201f994..ad89791902e7f 100644
--- a/clang/test/SemaCXX/align_value.cpp
+++ b/clang/test/SemaCXX/align_value.cpp
@@ -24,3 +24,17 @@ struct nope {
// expected-note@+1 {{in instantiation of template class 'nope<long double,
4>' requested here}}
nope<long double, 4> y2;
+namespace GH26612 {
+// This used to crash while issuing the diagnostic about only applying to a
+// pointer or reference type.
+// FIXME: it would be ideal to only diagnose once rather than twice. We get one
+// diagnostic from explicit template arguments and another one for deduced
+// template arguments, which seems silly.
+template <class T>
+void f(T __attribute__((align_value(4))) x) {} // expected-warning 2
{{'align_value' attribute only applies to a pointer or reference ('int' is
invalid)}}
+
+void foo() {
+ f<int>(0); // expected-note {{while substituting explicitly-specified
template arguments into function template 'f'}} \
+ expected-note {{while substituting deduced template arguments
into function template 'f' [with T = int]}}
+}
+} // namespace GH26612
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