https://github.com/llvmbot created
https://github.com/llvm/llvm-project/pull/150980
Backport 837b2d464ff16fe0d892dcf2827747c97dd5465e
Requested by: @AaronBallman
>From 197fbd01a89825c9bf80a2e174406fcb8e0cba71 Mon Sep 17 00:00:00 2001
From: Aaron Ballman <aa...@aaronballman.com>
Date: Mon, 28 Jul 2025 11:53:33 -0400
Subject: [PATCH] [[gnu::nonstring]] should work on pointers too (#150974)
Clang's current implementation only works on array types, but GCC (which
is where we got this attribute) supports it on pointers as well as
arrays.
Fixes #150951
(cherry picked from commit 837b2d464ff16fe0d892dcf2827747c97dd5465e)
---
clang/include/clang/Basic/AttrDocs.td | 6 +++---
clang/lib/Sema/SemaDeclAttr.cpp | 6 +++---
clang/test/Sema/attr-nonstring.c | 8 ++++++++
3 files changed, 14 insertions(+), 6 deletions(-)
diff --git a/clang/include/clang/Basic/AttrDocs.td
b/clang/include/clang/Basic/AttrDocs.td
index fefdaba7f8bf5..76747d2b11811 100644
--- a/clang/include/clang/Basic/AttrDocs.td
+++ b/clang/include/clang/Basic/AttrDocs.td
@@ -9417,9 +9417,9 @@ def NonStringDocs : Documentation {
let Category = DocCatDecl;
let Content = [{
The ``nonstring`` attribute can be applied to the declaration of a variable or
-a field whose type is a character array to specify that the character array is
-not intended to behave like a null-terminated string. This will silence
-diagnostics with code like:
+a field whose type is a character pointer or character array to specify that
+the buffer is not intended to behave like a null-terminated string. This will
+silence diagnostics with code like:
.. code-block:: c
diff --git a/clang/lib/Sema/SemaDeclAttr.cpp b/clang/lib/Sema/SemaDeclAttr.cpp
index 5f481ed1f7139..eff5f9568236a 100644
--- a/clang/lib/Sema/SemaDeclAttr.cpp
+++ b/clang/lib/Sema/SemaDeclAttr.cpp
@@ -5011,10 +5011,10 @@ void Sema::AddModeAttr(Decl *D, const
AttributeCommonInfo &CI,
static void handleNonStringAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
// This only applies to fields and variable declarations which have an array
- // type.
+ // type or pointer type, with character elements.
QualType QT = cast<ValueDecl>(D)->getType();
- if (!QT->isArrayType() ||
- !QT->getBaseElementTypeUnsafe()->isAnyCharacterType()) {
+ if ((!QT->isArrayType() && !QT->isPointerType()) ||
+ !QT->getPointeeOrArrayElementType()->isAnyCharacterType()) {
S.Diag(D->getBeginLoc(), diag::warn_attribute_non_character_array)
<< AL << AL.isRegularKeywordAttribute() << QT << AL.getRange();
return;
diff --git a/clang/test/Sema/attr-nonstring.c b/clang/test/Sema/attr-nonstring.c
index 3838aa3bbee15..fe7b6d259dd79 100644
--- a/clang/test/Sema/attr-nonstring.c
+++ b/clang/test/Sema/attr-nonstring.c
@@ -229,3 +229,11 @@ struct Outer o2[] = {
}
}
};
+
+// The attribute also works with a pointer type, not just an array type.
+__attribute__((nonstring)) char *ptr1;
+__attribute__((nonstring)) const unsigned char *ptr2;
+struct GH150951 {
+ __attribute__((nonstring)) char *ptr1;
+ __attribute__((nonstring)) const unsigned char *ptr2;
+};
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