clang/test/SemaCXX/attr-selectany.cpp

   1 // RUN: %clang_cc1 -triple x86_64-win32 -fms-compatibility -fms-extensions -fsyntax-only -verify -std=c++11 %s
   2 // RUN: %clang_cc1 -triple x86_64-unknown-linux -fms-compatibility -fms-extensions -fsyntax-only -verify -std=c++11 %s
   3 // RUN: %clang_cc1 -triple x86_64-win32-macho -fms-compatibility -fms-extensions -fsyntax-only -verify -std=c++11 %s
   4
   5 // MSVC produces similar diagnostics.
   6
   7 __declspec(selectany) void foo() { } // expected-error{{'selectany' can only be applied to data items with external linkage}}
   8
   9 __declspec(selectany) int x1 = 1;
  10
  11 const __declspec(selectany) int x2 = 2; // expected-error{{'selectany' can only be applied to data items with external linkage}}
  12
  13 extern const __declspec(selectany) int x3 = 3;
  14
  15 extern const int x4;
  16 const __declspec(selectany) int x4 = 4;
  17
  18 // MSDN says this is incorrect, but MSVC doesn't diagnose it.
  19 extern __declspec(selectany) int x5;
  20
  21 static __declspec(selectany) int x6 = 2; // expected-error{{'selectany' can only be applied to data items with external linkage}}
  22
  23 // FIXME: MSVC accepts this and makes x7 externally visible and comdat, but keep
  24 // it as internal and not weak/linkonce.
  25 static int x7; // expected-note{{previous definition}}
  26 extern __declspec(selectany) int x7;  // expected-warning{{attribute declaration must precede definition}}
  27
  28 int asdf() { return x7; }
  29
  30 class X {
  31  public:
  32   X(int i) { i++; };
  33   int i;
  34 };
  35
  36 __declspec(selectany) X x(1);
  37
  38 namespace { class Internal {}; }
  39 __declspec(selectany) auto x8 = Internal(); // expected-error {{'selectany' can only be applied to data items with external linkage}}
  40
  41
  42 // The D3D11 headers do something like this.  MSVC doesn't error on this at
  43 // all, even without the __declspec(selectany), in violation of the standard.
  44 // We fall back to a warning for selectany to accept headers.
  45 struct SomeStruct {
  46   int foo;
  47 };
  48 extern const __declspec(selectany) SomeStruct some_struct; // expected-warning {{default initialization of an object of const type 'const SomeStruct' without a user-provided default constructor is a Microsoft extension}}
  49
  50 // It should be possible to redeclare variables that were defined
  51 // __declspec(selectany) previously.
  52 extern const SomeStruct some_struct;
  53
  54 // Without selectany, this should stay an error.
  55 const SomeStruct some_struct2; // expected-error {{default initialization of an object of const type 'const SomeStruct' without a user-provided default constructor}}