[PATCH] D102122: Support warn_unused_result on typedefs

[David Blaikie via Phabricator via cfe-commits]

dblaikie updated this revision to Diff 432091.
dblaikie added a comment.

Rebase


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/test/CXX/dcl.dcl/dcl.attr/dcl.attr.nodiscard/p1.cpp
  clang/test/Misc/pragma-attribute-supported-attributes-list.test
  clang/test/Sema/c2x-nodiscard.c
  clang/test/Sema/unused-expr.c
  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/Sema/unused-expr.c
===================================================================
--- clang/test/Sema/unused-expr.c
+++ clang/test/Sema/unused-expr.c
@@ -96,7 +96,7 @@
   return 0;
 }
 
-int t7 __attribute__ ((warn_unused_result)); // expected-warning {{'warn_unused_result' attribute only applies to Objective-C methods, enums, structs, unions, classes, functions, and function pointers}}
+int t7 __attribute__ ((warn_unused_result)); // expected-warning {{'warn_unused_result' attribute only applies to Objective-C methods, enums, structs, unions, classes, functions, function pointers, and typedefs}}
 
 // PR4010
 int (*fn4)(void) __attribute__ ((warn_unused_result));
Index: clang/test/Sema/c2x-nodiscard.c
===================================================================
--- clang/test/Sema/c2x-nodiscard.c
+++ clang/test/Sema/c2x-nodiscard.c
@@ -15,7 +15,7 @@
 [[nodiscard]] int f1(void);
 enum [[nodiscard]] E1 { One };
 
-[[nodiscard]] int i; // expected-warning {{'nodiscard' attribute only applies to Objective-C methods, enums, structs, unions, classes, functions, and function pointers}}
+[[nodiscard]] int i; // expected-warning {{'nodiscard' attribute only applies to Objective-C methods, enums, structs, unions, classes, functions, function pointers, and typedefs}}
 
 struct [[nodiscard]] S4 {
   int i;
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
@@ -185,7 +185,7 @@
 // CHECK-NEXT: VecReturn (SubjectMatchRule_record)
 // 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: WarnUnusedResult (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/test/CXX/dcl.dcl/dcl.attr/dcl.attr.nodiscard/p1.cpp
===================================================================
--- clang/test/CXX/dcl.dcl/dcl.attr/dcl.attr.nodiscard/p1.cpp
+++ clang/test/CXX/dcl.dcl/dcl.attr/dcl.attr.nodiscard/p1.cpp
@@ -7,4 +7,4 @@
 [[nodiscard]] int f();
 enum [[nodiscard]] E {};
 
-namespace [[nodiscard]] N {} // expected-warning {{'nodiscard' attribute only applies to Objective-C methods, enums, structs, unions, classes, functions, and function pointers}}
+namespace [[nodiscard]] N {} // expected-warning {{'nodiscard' attribute only applies to Objective-C methods, enums, structs, unions, classes, functions, function pointers, and typedefs}}
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
@@ -2944,7 +2944,7 @@
                    C2x<"", "nodiscard", 201904>,
                    CXX11<"clang", "warn_unused_result">,
                    GCC<"warn_unused_result">];
-  let Subjects = SubjectList<[ObjCMethod, Enum, Record, FunctionLike]>;
+  let Subjects = SubjectList<[ObjCMethod, Enum, Record, FunctionLike, TypedefName]>;
   let Args = [StringArgument<"Message", 1>];
   let Documentation = [WarnUnusedResultsDocs];
   let AdditionalMembers = [{


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