clang/test/SemaCXX/function-extern-c.cpp

   1 // RUN: %clang_cc1 -Wreturn-type -fsyntax-only -std=c++11 -verify %s
   2
   3 class A {
   4 public:
   5   A(const A&);
   6 };
   7
   8 struct S {
   9   int i;
  10   double d;
  11
  12   virtual void B() {}
  13 };
  14
  15 union U {
  16   struct {
  17     int i;
  18     virtual void B() {} // Can only do this in C++11
  19   } t;
  20 };
  21
  22 struct S2 {
  23   int i;
  24   double d;
  25 };
  26
  27 extern "C" U f3( void ); // expected-warning {{'f3' has C-linkage specified, but returns user-defined type 'U' which is incompatible with C}}
  28 extern "C" S f0(void); // expected-warning {{'f0' has C-linkage specified, but returns user-defined type 'S' which is incompatible with C}}
  29 extern "C" A f4( void ); // expected-warning {{'f4' has C-linkage specified, but returns user-defined type 'A' which is incompatible with C}}
  30
  31 // These should all be fine
  32 extern "C" S2 f5( void );
  33 extern "C" void f2( A x );
  34 extern "C" void f6( S s );
  35 extern "C" void f7( U u );
  36 extern "C" double f8(void);
  37 extern "C" long long f11( void );
  38 extern "C" A *f10( void );
  39
  40 extern "C" struct mypodstruct f12(); // expected-warning {{'f12' has C-linkage specified, but returns incomplete type 'struct mypodstruct' which could be incompatible with C}}
  41
  42 namespace test2 {
  43   // FIXME: we should probably suppress the first warning as the second one
  44   // is more precise.
  45   // For now this tests that a second 'extern "C"' is not necessary to trigger
  46   // the warning.
  47   struct A;
  48   extern "C" A f(void); // expected-warning {{'f' has C-linkage specified, but returns incomplete type 'A' which could be incompatible with C}}
  49   struct A {
  50     A(const A&);
  51   };
  52   A f(void);  // no warning. warning is already issued on first declaration.
  53 }
  54
  55 namespace test3 {
  56   struct A {
  57     A(const A&);
  58   };
  59   extern "C" {
  60     // Don't warn for static functions.
  61     static A f(void);
  62   }
  63 }
  64
  65 namespace rdar13364028 {
  66 class A {
  67 public:
  68     virtual int x();
  69 };
  70
  71 extern "C" {
  72 #pragma clang diagnostic push
  73 #pragma clang diagnostic ignored "-Wreturn-type-c-linkage"
  74 A xyzzy();
  75 #pragma clang diagnostic pop
  76 A bbb(); // expected-warning {{'bbb' has C-linkage specified, but returns user-defined type 'A' which is incompatible with C}}
  77 A ccc() { // expected-warning {{'ccc' has C-linkage specified, but returns user-defined type 'A' which is incompatible with C}}
  78   return A();
  79 };
  80 }
  81
  82 A xyzzy();
  83
  84 A xyzzy()
  85 {
  86   return A();
  87 }
  88
  89 A bbb()
  90 {
  91   return A();
  92 }
  93
  94 A bbb();
  95
  96 A ccc();
  97 }