[PATCH] D102122: Support warn_unused_result on typedefs

[David Blaikie via Phabricator via cfe-commits]

dblaikie updated this revision to Diff 432131.
dblaikie added a comment.

Separate out clang:warn_unused_result so typedef support can be added to only that spelling.

This has one lingering issue (because it still currently instantiates both the clang:warn_unused_result as the same *Attr class as the others - and so SemaCXX/cxx11-attr-print.cpp is failing because the AST printing for the clang spelling decides to use the C++ standard spelling, I guess because the non-clang Attr class doesn't realize it was spelled with the clang spelling)


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D102122/new/

https://reviews.llvm.org/D102122

Files:
  clang/include/clang/Basic/Attr.td
  clang/lib/AST/Expr.cpp
  clang/lib/Sema/SemaDeclAttr.cpp
  clang/test/Misc/pragma-attribute-supported-attributes-list.test
  clang/test/SemaCXX/warn-unused-result.cpp


Index: clang/test/SemaCXX/warn-unused-result.cpp
===================================================================
--- clang/test/SemaCXX/warn-unused-result.cpp
+++ clang/test/SemaCXX/warn-unused-result.cpp
@@ -254,3 +254,15 @@
 
 void i([[nodiscard]] bool (*fp)()); // expected-warning {{'nodiscard' attribute only applies to functions, classes, or enumerations}}
 }
+
+namespace unused_typedef_result {
+[[clang::warn_unused_result]] typedef void *p;
+p f1();
+void f2() {
+  f1(); // expected-warning {{ignoring return value}}
+  void *(*p1)();
+  p1(); // no warning
+  p (*p2)();
+  p2(); // expected-warning {{ignoring return value}}
+}
+}
Index: clang/test/Misc/pragma-attribute-supported-attributes-list.test
===================================================================
--- clang/test/Misc/pragma-attribute-supported-attributes-list.test
+++ clang/test/Misc/pragma-attribute-supported-attributes-list.test
@@ -186,6 +186,7 @@
 // CHECK-NEXT: VecTypeHint (SubjectMatchRule_function)
 // CHECK-NEXT: WarnUnused (SubjectMatchRule_record)
 // CHECK-NEXT: WarnUnusedResult (SubjectMatchRule_objc_method, SubjectMatchRule_enum, SubjectMatchRule_record, SubjectMatchRule_hasType_functionType)
+// CHECK-NEXT: WarnUnusedResultClang (SubjectMatchRule_objc_method, SubjectMatchRule_enum, SubjectMatchRule_record, SubjectMatchRule_hasType_functionType, SubjectMatchRule_type_alias)
 // CHECK-NEXT: Weak (SubjectMatchRule_variable, SubjectMatchRule_function, SubjectMatchRule_record)
 // CHECK-NEXT: WeakRef (SubjectMatchRule_variable, SubjectMatchRule_function)
 // CHECK-NEXT: WebAssemblyExportName (SubjectMatchRule_function)
Index: clang/lib/Sema/SemaDeclAttr.cpp
===================================================================
--- clang/lib/Sema/SemaDeclAttr.cpp
+++ clang/lib/Sema/SemaDeclAttr.cpp
@@ -8740,6 +8740,9 @@
   case ParsedAttr::AT_WarnUnusedResult:
     handleWarnUnusedResult(S, D, AL);
     break;
+  case ParsedAttr::AT_WarnUnusedResultClang:
+    handleWarnUnusedResult(S, D, AL);
+    break;
   case ParsedAttr::AT_WeakRef:
     handleWeakRefAttr(S, D, AL);
     break;
Index: clang/lib/AST/Expr.cpp
===================================================================
--- clang/lib/AST/Expr.cpp
+++ clang/lib/AST/Expr.cpp
@@ -1522,6 +1522,10 @@
     if (const auto *A = TD->getAttr<WarnUnusedResultAttr>())
       return A;
 
+  if (const auto *TD = getCallReturnType(Ctx)->getAs<TypedefType>())
+    if (const auto *A = TD->getDecl()->getAttr<WarnUnusedResultAttr>())
+      return A;
+
   // Otherwise, see if the callee is marked nodiscard and return that attribute
   // instead.
   const Decl *D = getCalleeDecl();
Index: clang/include/clang/Basic/Attr.td
===================================================================
--- clang/include/clang/Basic/Attr.td
+++ clang/include/clang/Basic/Attr.td
@@ -2939,10 +2939,16 @@
   let SimpleHandler = 1;
 }
 
+def WarnUnusedResultClang : InheritableAttr {
+  let Spellings = [CXX11<"clang", "warn_unused_result">];
+  let Subjects = SubjectList<[ObjCMethod, Enum, Record, FunctionLike, TypedefName]>;
+  let Args = [StringArgument<"Message", 1>];
+  let Documentation = [WarnUnusedResultsDocs];
+}
+
 def WarnUnusedResult : InheritableAttr {
   let Spellings = [CXX11<"", "nodiscard", 201907>,
                    C2x<"", "nodiscard", 201904>,
-                   CXX11<"clang", "warn_unused_result">,
                    GCC<"warn_unused_result">];
   let Subjects = SubjectList<[ObjCMethod, Enum, Record, FunctionLike]>;
   let Args = [StringArgument<"Message", 1>];


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