[clang] Fix spurious availability warning (PR #94377)

[via cfe-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang

Author: Gábor Horváth (Xazax-hun)

<details>
<summary>Changes</summary>

The availability attributes are stored on the function declarations. The code was looking for them in the function template declarations. This resulted in spuriously diagnosing availablity issues in contexts that are not available.

---
Full diff: https://github.com/llvm/llvm-project/pull/94377.diff


3 Files Affected:

- (modified) clang/include/clang/Sema/Initialization.h (+1-1) 
- (modified) clang/lib/Sema/SemaAvailability.cpp (+5) 
- (added) clang/test/Sema/attr-availability-macosx.cpp (+17) 


``````````diff
diff --git a/clang/include/clang/Sema/Initialization.h b/clang/include/clang/Sema/Initialization.h
index 2072cd8d1c3ef..f443e327eaf32 100644
--- a/clang/include/clang/Sema/Initialization.h
+++ b/clang/include/clang/Sema/Initialization.h
@@ -212,7 +212,7 @@ class alignas(8) InitializedEntity {
     struct C Capture;
   };
 
-  InitializedEntity() {};
+  InitializedEntity() {}
 
   /// Create the initialization entity for a variable.
   InitializedEntity(VarDecl *Var, EntityKind EK = EK_Variable)
diff --git a/clang/lib/Sema/SemaAvailability.cpp b/clang/lib/Sema/SemaAvailability.cpp
index 330cd602297d4..3e5f90b450367 100644
--- a/clang/lib/Sema/SemaAvailability.cpp
+++ b/clang/lib/Sema/SemaAvailability.cpp
@@ -12,6 +12,7 @@
 
 #include "clang/AST/Attr.h"
 #include "clang/AST/Decl.h"
+#include "clang/AST/DeclTemplate.h"
 #include "clang/AST/RecursiveASTVisitor.h"
 #include "clang/Basic/DiagnosticSema.h"
 #include "clang/Basic/IdentifierTable.h"
@@ -46,6 +47,10 @@ static const AvailabilityAttr *getAttrForPlatform(ASTContext &Context,
   // Check each AvailabilityAttr to find the one for this platform.
   // For multiple attributes with the same platform try to find one for this
   // environment.
+  // The attribute is always on the FunctionDecl, not on the
+  // FunctionTemplateDecl.
+  if (const auto *FTD = dyn_cast<FunctionTemplateDecl>(D))
+    D = FTD->getTemplatedDecl();
   for (const auto *A : D->attrs()) {
     if (const auto *Avail = dyn_cast<AvailabilityAttr>(A)) {
       // FIXME: this is copied from CheckAvailability. We should try to
diff --git a/clang/test/Sema/attr-availability-macosx.cpp b/clang/test/Sema/attr-availability-macosx.cpp
new file mode 100644
index 0000000000000..52f320d409281
--- /dev/null
+++ b/clang/test/Sema/attr-availability-macosx.cpp
@@ -0,0 +1,17 @@
+// RUN: %clang_cc1 "-triple" "arm64-apple-macosx10.15" -fsyntax-only -verify %s
+
+__attribute__((availability(macos,introduced=11)))
+inline bool try_acquire() {
+  return true;
+}
+
+template <class T>
+__attribute__((availability(macos,introduced=11)))
+bool try_acquire_for(T duration) { // expected-note{{'try_acquire_for<int>' has been marked as being introduced in macOS 11 here, but the deployment target is macOS 10.15}}
+  return try_acquire();
+}
+
+int main() {
+  try_acquire_for(1); // expected-warning{{'try_acquire_for<int>' is only available on macOS 11 or newer}}
+  // expected-note at -1{{enclose 'try_acquire_for<int>' in a __builtin_available check to silence this warning}}
+}
\ No newline at end of file

``````````

</details>


https://github.com/llvm/llvm-project/pull/94377