[Clang]: enhance handling of [[deprecated]] attribute diagnostics for local variables

[a-tarasyuk]

Fixes #90073

[llvmbot]

@llvm/pr-subscribers-clang

Author: Oleksandr T. (a-tarasyuk)

Changes

Fixes #90073

---

Full diff: https://github.com/llvm/llvm-project/pull/113575.diff

3 Files Affected:

• (modified) clang/docs/ReleaseNotes.rst (+2)
• (modified) clang/lib/Sema/SemaAvailability.cpp (+6)
• (modified) clang/test/SemaCXX/deprecated.cpp (+14)

diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 28bb83a1c9d60f..89c97d4b6631f2 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -424,6 +424,8 @@ Improvements to Clang's diagnostics
   name was a reserved name, which we improperly allowed to suppress the
   diagnostic.
 
+- Clang now diagnoses [[deprecated]] attribute usage on local variables (#GH90073).
+
 Improvements to Clang's time-trace
 ----------------------------------
 
diff --git a/clang/lib/Sema/SemaAvailability.cpp b/clang/lib/Sema/SemaAvailability.cpp
index 798cabaa31a476..d62b3eb1a480e7 100644
--- a/clang/lib/Sema/SemaAvailability.cpp
+++ b/clang/lib/Sema/SemaAvailability.cpp
@@ -182,6 +182,12 @@ static bool ShouldDiagnoseAvailabilityInContext(
       return false;
   }
 
+  if (K == AR_Deprecated) {
+    if (const auto *VD = dyn_cast<VarDecl>(OffendingDecl))
+      if (VD->isLocalVarDecl() && VD->isDeprecated())
+        return true;
+  }
+
   // Checks if we should emit the availability diagnostic in the context of C.
   auto CheckContext = [&](const Decl *C) {
     if (K == AR_NotYetIntroduced) {
diff --git a/clang/test/SemaCXX/deprecated.cpp b/clang/test/SemaCXX/deprecated.cpp
index a93331023f7e21..02fdf0bec5c088 100644
--- a/clang/test/SemaCXX/deprecated.cpp
+++ b/clang/test/SemaCXX/deprecated.cpp
@@ -260,5 +260,19 @@ namespace ArrayComp {
   bool b7 = arr1 == +f();
 }
 
+namespace GH90073 {
+[[deprecated]] int f() { // expected-note {{'f' has been explicitly marked deprecated here}}
+  [[deprecated]] int a;  // expected-note {{'a' has been explicitly marked deprecated here}} \
+                         // expected-note {{'a' has been explicitly marked deprecated here}}
+  a = 0;    // expected-warning {{'a' is deprecated}}
+  return a; // expected-warning {{'a' is deprecated}}
+}
+
+int main() {
+  f(); // expected-warning {{'f' is deprecated}}
+  return 0;
+}
+}
+
 # 1 "/usr/include/system-header.h" 1 3
 void system_header_function(void) throw();

[Sirraide]

LGTM

On the issue for this, there was some discussion about the fact that the standard might disallow deprecating local variables at some point, but so long as we (still) allow that, it only makes sense to actually diagnose the deprecation as well considering that it seems to be straight-forward enough to implement.