[clang] cd754af - [Clang] Permit both `gnu` and `clang` prefixes on some attributes (#125796)

[via cfe-commits]

Author: Joseph Huber
Date: 2025-02-05T08:16:00-06:00
New Revision: cd754af55f5b7f6f5371852843bc3613866232c2

URL: https://github.com/llvm/llvm-project/commit/cd754af55f5b7f6f5371852843bc3613866232c2
DIFF: https://github.com/llvm/llvm-project/commit/cd754af55f5b7f6f5371852843bc3613866232c2.diff

LOG: [Clang] Permit both `gnu` and `clang` prefixes on some attributes (#125796)

Summary:
Some attributes have gnu extensions that share names with clang
attributes. If these imply the same thing, we can specially declare this
to be an alternate but equivalent spelling. This patch enables this for
`no_sanitize` and provides the infrastructure for more to be added if
needed.

Discussions welcome on whether or not we want to bind ourselves to GNU
behavior, since theoretically it's possible for GNU to silently change
the semantics away from our implementation, but I'm not an expert.

Fixes: https://github.com/llvm/llvm-project/issues/125760

Added: 
    

Modified: 
    clang/docs/ReleaseNotes.rst
    clang/include/clang/Basic/Attr.td
    clang/test/SemaCXX/attr-no-sanitize.cpp
    clang/utils/TableGen/ClangAttrEmitter.cpp

Removed: 
    


################################################################################
diff  --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 87d2544a30ed818..f7feca0089f94d3 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -112,6 +112,8 @@ Removed Compiler Flags
 Attribute Changes in Clang
 --------------------------
 
+- The ``no_sanitize`` attribute now accepts both ``gnu`` and ``clang`` names.
+
 Improvements to Clang's diagnostics
 -----------------------------------
 

diff  --git a/clang/include/clang/Basic/Attr.td b/clang/include/clang/Basic/Attr.td
index 2a3a29bd2ee1cf4..4384a98d63eb3df 100644
--- a/clang/include/clang/Basic/Attr.td
+++ b/clang/include/clang/Basic/Attr.td
@@ -380,6 +380,13 @@ class Clang<string name, bit allowInC = 1, int version = 1>
   bit AllowInC = allowInC;
 }
 
+// This spelling combines the spellings of GCC and Clang for cases where the
+// spellings are equivalent for compile compatibility.
+class ClangGCC<string name, bit allowInC = 1, int version = 1>
+    : Spelling<name, "ClangGCC", version> {
+  bit AllowInC = allowInC;
+}
+
 // HLSL Annotation spellings
 class HLSLAnnotation<string name> : Spelling<name, "HLSLAnnotation">;
 
@@ -3677,7 +3684,7 @@ def X86ForceAlignArgPointer : InheritableAttr, TargetSpecificAttr<TargetAnyX86>
 }
 
 def NoSanitize : InheritableAttr {
-  let Spellings = [Clang<"no_sanitize">];
+  let Spellings = [ClangGCC<"no_sanitize">];
   let Args = [VariadicStringArgument<"Sanitizers">];
   let Subjects = SubjectList<[Function, ObjCMethod, GlobalVar], ErrorDiag>;
   let Documentation = [NoSanitizeDocs];

diff  --git a/clang/test/SemaCXX/attr-no-sanitize.cpp b/clang/test/SemaCXX/attr-no-sanitize.cpp
index 8951f616ce0f056..cd60e71963ac30a 100644
--- a/clang/test/SemaCXX/attr-no-sanitize.cpp
+++ b/clang/test/SemaCXX/attr-no-sanitize.cpp
@@ -21,8 +21,8 @@ int f3() __attribute__((no_sanitize("address")));
 
 // DUMP-LABEL: FunctionDecl {{.*}} f4
 // DUMP: NoSanitizeAttr {{.*}} hwaddress
-// PRINT: {{\[\[}}clang::no_sanitize("hwaddress")]] int f4()
-[[clang::no_sanitize("hwaddress")]] int f4();
+// PRINT: {{\[\[}}gnu::no_sanitize("hwaddress")]] int f4()
+[[gnu::no_sanitize("hwaddress")]] int f4();
 
 // DUMP-LABEL: FunctionDecl {{.*}} f5
 // DUMP: NoSanitizeAttr {{.*}} address thread hwaddress

diff  --git a/clang/utils/TableGen/ClangAttrEmitter.cpp b/clang/utils/TableGen/ClangAttrEmitter.cpp
index de12c7062666a45..af7478b7986f92b 100644
--- a/clang/utils/TableGen/ClangAttrEmitter.cpp
+++ b/clang/utils/TableGen/ClangAttrEmitter.cpp
@@ -108,6 +108,14 @@ GetFlattenedSpellings(const Record &Attr) {
       Ret.emplace_back("CXX11", Name, "clang", false, *Spelling);
       if (Spelling->getValueAsBit("AllowInC"))
         Ret.emplace_back("C23", Name, "clang", false, *Spelling);
+    } else if (Variety == "ClangGCC") {
+      Ret.emplace_back("GNU", Name, "", false, *Spelling);
+      Ret.emplace_back("CXX11", Name, "clang", false, *Spelling);
+      Ret.emplace_back("CXX11", Name, "gnu", false, *Spelling);
+      if (Spelling->getValueAsBit("AllowInC")) {
+        Ret.emplace_back("C23", Name, "clang", false, *Spelling);
+        Ret.emplace_back("C23", Name, "gnu", false, *Spelling);
+      }
     } else {
       Ret.push_back(FlattenedSpelling(*Spelling));
     }