function-extern-c.cpp
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// RUN: %clang_cc1 -Wreturn-type -fsyntax-only -std=c++11 -verify %s
class A {
public:
A(const A&);
};
struct S {
int i;
double d;
virtual void B() {}
};
union U {
struct {
int i;
virtual void B() {} // Can only do this in C++11
} t;
};
struct S2 {
int i;
double d;
};
extern "C" U f3( void ); // expected-warning {{'f3' has C-linkage specified, but returns user-defined type 'U' which is incompatible with C}}
extern "C" S f0(void); // expected-warning {{'f0' has C-linkage specified, but returns user-defined type 'S' which is incompatible with C}}
extern "C" A f4( void ); // expected-warning {{'f4' has C-linkage specified, but returns user-defined type 'A' which is incompatible with C}}
// These should all be fine
extern "C" S2 f5( void );
extern "C" void f2( A x );
extern "C" void f6( S s );
extern "C" void f7( U u );
extern "C" double f8(void);
extern "C" long long f11( void );
extern "C" A *f10( void );
extern "C" struct mypodstruct f12(); // expected-warning {{'f12' has C-linkage specified, but returns incomplete type 'struct mypodstruct' which could be incompatible with C}}
namespace test2 {
// FIXME: we should probably suppress the first warning as the second one
// is more precise.
// For now this tests that a second 'extern "C"' is not necessary to trigger
// the warning.
struct A;
extern "C" A f(void); // expected-warning {{'f' has C-linkage specified, but returns incomplete type 'test2::A' which could be incompatible with C}}
struct A {
A(const A&);
};
A f(void); // no warning. warning is already issued on first declaration.
}
namespace test3 {
struct A {
A(const A&);
};
extern "C" {
// Don't warn for static functions.
static A f(void);
}
}
// rdar://13364028
namespace rdar13364028 {
class A {
public:
virtual int x();
};
extern "C" {
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wreturn-type-c-linkage"
A xyzzy();
#pragma clang diagnostic pop
A bbb(); // expected-warning {{'bbb' has C-linkage specified, but returns user-defined type 'rdar13364028::A' which is incompatible with C}}
A ccc() { // expected-warning {{'ccc' has C-linkage specified, but returns user-defined type 'rdar13364028::A' which is incompatible with C}}
return A();
};
}
A xyzzy();
A xyzzy()
{
return A();
}
A bbb()
{
return A();
}
A bbb();
A ccc();
}