clang/test/CXX/dcl.dcl/dcl.attr/dcl.attr.unused/p3.cpp

   1 // RUN: %clang_cc1 -fsyntax-only -Wunused -Wused-but-marked-unused -std=c++17 -Wc++17-extensions -verify %s
   2 // RUN: %clang_cc1 -fsyntax-only -Wunused -Wused-but-marked-unused -std=c++11 -Wc++17-extensions -verify -DEXT %s
   3
   4 static_assert(__has_cpp_attribute(maybe_unused) == 201603, "");
   5
   6 struct [[maybe_unused]] S {};
   7
   8 enum E1 {
   9   EnumVal [[maybe_unused]],
  10   UsedEnumVal,
  11 };
  12
  13 void f() {
  14   int x; // expected-warning {{unused variable}}
  15   typedef int I; // expected-warning {{unused typedef 'I'}}
  16   E1 e;
  17   switch (e) { // expected-warning {{enumeration value 'UsedEnumVal' not handled in switch}}
  18   }
  19
  20   // Should not warn about these due to not being used.
  21   [[maybe_unused]] int y;
  22   typedef int maybe_unused_int [[maybe_unused]];
  23
  24   // Should not warn about these uses.
  25   S s;
  26   maybe_unused_int test;
  27   y = 12;
  28   switch (e) {
  29   case UsedEnumVal:
  30     break;
  31   }
  32 }
  33
  34 #ifdef EXT
  35 // expected-warning@6 {{use of the 'maybe_unused' attribute is a C++17 extension}}
  36 // expected-warning@9 {{use of the 'maybe_unused' attribute is a C++17 extension}}
  37 // expected-warning@9 {{attributes on an enumerator declaration are a C++17 extension}}
  38 // expected-warning@21 {{use of the 'maybe_unused' attribute is a C++17 extension}}
  39 // expected-warning@22 {{use of the 'maybe_unused' attribute is a C++17 extension}}
  40 #endif