1 // RUN: %clang_cc1 -fsyntax-only -verify %s 2 3 namespace test1 { 4 extern "C" { 5 void test1_f() { 6 void test1_g(int); 7 } 8 } 9 } 10 int test1_g(int); 11 12 namespace test2 { 13 extern "C" { 14 void test2_f() { 15 extern int test2_x; // expected-note {{declared with C language linkage here}} 16 } 17 } 18 } 19 float test2_x; // expected-error {{declaration of 'test2_x' in global scope conflicts with declaration with C language linkage}} 20 21 namespace test3 { 22 extern "C" { 23 void test3_f() { 24 extern int test3_b; // expected-note {{previous declaration is here}} 25 } 26 } 27 extern "C" { 28 float test3_b; // expected-error {{redefinition of 'test3_b' with a different type: 'float' vs 'int'}} 29 } 30 } 31 32 namespace N { 33 extern "C" { 34 void test4_f() { 35 extern int test4_b; // expected-note {{declared with C language linkage here}} 36 } 37 } 38 } 39 static float test4_b; // expected-error {{declaration of 'test4_b' in global scope conflicts with declaration with C language linkage}} 40 41 extern "C" { 42 void test4c_f() { 43 extern int test4_c; // expected-note {{previous}} 44 } 45 } 46 static float test4_c; // expected-error {{redefinition of 'test4_c' with a different type: 'float' vs 'int'}} 47 48 namespace N { 49 extern "C" { 50 void test5_f() { 51 extern int test5_b; // expected-note {{declared with C language linkage here}} 52 } 53 } 54 } 55 extern "C" { 56 static float test5_b; // expected-error {{declaration of 'test5_b' in global scope conflicts with declaration with C language linkage}} 57 } 58 59 extern "C" { 60 void test5c_f() { 61 extern int test5_c; // expected-note {{previous}} 62 } 63 } 64 extern "C" { 65 static float test5_c; // expected-error {{redefinition of 'test5_c' with a different type: 'float' vs 'int'}} 66 } 67 68 extern "C" { 69 void f() { 70 extern int test6_b; 71 } 72 } 73 namespace foo { 74 extern "C" { 75 static float test6_b; 76 extern float test6_b; 77 } 78 } 79 80 namespace extern_ovl { 81 extern "C" { 82 __attribute__((overloadable)) 83 void ovl_decl(void); // expected-note {{previous}} 84 85 __attribute__((overloadable)) 86 int ovl_decl(int); 87 88 __attribute__((overloadable)) 89 int ovl_decl(void); // expected-error {{functions that differ only in their return type}} 90 } 91 } 92 93 namespace linkage { 94 namespace redecl { 95 extern "C" { 96 static void linkage_redecl(); 97 static void linkage_redecl(int); 98 void linkage_redecl(); // ok, still not extern "C" 99 void linkage_redecl(int); // ok, still not extern "C" 100 void linkage_redecl(float); // expected-note {{previous}} 101 void linkage_redecl(double); // expected-error {{conflicting types}} 102 } 103 } 104 namespace redecl_2 { 105 extern "C" { 106 void linkage_redecl_2(); // expected-note {{previous}} 107 int linkage_redecl_2(int); // expected-error {{conflicting types}} 108 } 109 } 110 namespace from_outer { 111 void linkage_from_outer_1(); // expected-note {{previous}} 112 void linkage_from_outer_2(); // expected-note {{previous}} 113 extern "C" { 114 void linkage_from_outer_1(int); 115 void linkage_from_outer_1(); // expected-error {{different language linkage}} 116 void linkage_from_outer_2(); // expected-error {{different language linkage}} 117 } 118 } 119 namespace mixed { 120 extern "C" { 121 void linkage_mixed_1(); 122 static void linkage_mixed_1(int); 123 124 static void linkage_mixed_2(int); 125 void linkage_mixed_2(); 126 } 127 } 128 namespace across_scopes { 129 namespace X { 130 extern "C" void linkage_across_scopes_f() { 131 void linkage_across_scopes_g(); // expected-note {{previous}} 132 } 133 } 134 namespace Y { 135 extern "C" void linkage_across_scopes_g(int); // expected-error {{conflicting}} 136 } 137 } 138 } 139 140 int lookup_in_global_f; // expected-note {{here}} 141 namespace lookup_in_global { 142 void lookup_in_global_f(); 143 void lookup_in_global_g(); 144 extern "C" { 145 void lookup_in_global_f(int); // expected-error {{conflicts with declaration in global scope}} 146 void lookup_in_global_g(int); // expected-note {{here}} 147 } 148 } 149 int lookup_in_global_g; // expected-error {{conflicts with declaration with C language linkage}} 150 151 namespace N1 { 152 extern "C" int different_kind_1; // expected-note {{here}} 153 extern "C" void different_kind_2(); // expected-note {{here}} 154 } 155 namespace N2 { 156 extern "C" void different_kind_1(); // expected-error {{different kind of symbol}} 157 extern "C" int different_kind_2; // expected-error {{different kind of symbol}} 158 } 159 160 // We allow all these even though the standard says they are ill-formed. 161 extern "C" { 162 struct stat {}; // expected-warning{{empty struct has size 0 in C, size 1 in C++}} 163 void stat(struct stat); 164 } 165 namespace X { 166 extern "C" { 167 void stat(struct ::stat); 168 } 169 } 170 int stat(int *p); 171 void global_fn_vs_extern_c_var_1(); 172 namespace X { 173 extern "C" int global_fn_vs_extern_c_var_1; 174 extern "C" int global_fn_vs_extern_c_var_2; 175 } 176 void global_fn_vs_extern_c_var_2(); 177 void global_fn_vs_extern_c_fn_1(); 178 namespace X { 179 extern "C" int global_fn_vs_extern_c_fn_1(int); 180 extern "C" int global_fn_vs_extern_c_fn_2(int); 181 } 182 void global_fn_vs_extern_c_fn_2(); 183 extern "C" void name_with_using_decl_1(int); 184 namespace using_decl { 185 void name_with_using_decl_1(); 186 void name_with_using_decl_2(); 187 void name_with_using_decl_3(); 188 } 189 using using_decl::name_with_using_decl_1; 190 using using_decl::name_with_using_decl_2; 191 extern "C" void name_with_using_decl_2(int); 192 extern "C" void name_with_using_decl_3(int); 193 using using_decl::name_with_using_decl_3; 194 195 // We do not allow a global variable and an extern "C" function to have the same 196 // name, because such entities may have the same mangled name. 197 int global_var_vs_extern_c_fn_1; // expected-note {{here}} 198 namespace X { 199 extern "C" void global_var_vs_extern_c_fn_1(); // expected-error {{conflicts with declaration in global scope}} 200 extern "C" void global_var_vs_extern_c_fn_2(); // expected-note {{here}} 201 } 202 int global_var_vs_extern_c_fn_2; // expected-error {{conflicts with declaration with C language linkage}} 203 int global_var_vs_extern_c_var_1; // expected-note {{here}} 204 namespace X { 205 extern "C" double global_var_vs_extern_c_var_1; // expected-error {{conflicts with declaration in global scope}} 206 extern "C" double global_var_vs_extern_c_var_2; // expected-note {{here}} 207 } 208 int global_var_vs_extern_c_var_2; // expected-error {{conflicts with declaration with C language linkage}} 209 210 template <class T> struct pr5065_n1 {}; 211 extern "C" { 212 union pr5065_1 {}; // expected-warning{{empty union has size 0 in C, size 1 in C++}} 213 struct pr5065_2 { int: 0; }; // expected-warning{{struct has size 0 in C, size 1 in C++}} 214 struct pr5065_3 {}; // expected-warning{{empty struct has size 0 in C, size 1 in C++}} 215 struct pr5065_4 { // expected-warning{{empty struct has size 0 in C, size 1 in C++}} 216 struct Inner {}; // expected-warning{{empty struct has size 0 in C, size 1 in C++}} 217 }; 218 // These should not warn 219 class pr5065_n3 {}; 220 pr5065_n1<int> pr5065_v; 221 struct pr5065_n4 { void m() {} }; 222 struct pr5065_n5 : public pr5065_3 {}; 223 struct pr5065_n6 : public virtual pr5065_3 {}; 224 } 225 struct pr5065_n7 {}; 226 227 namespace tag_hiding { 228 namespace namespace_with_injected_name { 229 class Boo { 230 friend struct ExternCStruct1; 231 }; 232 void ExternCStruct4(); // expected-note 2{{candidate}} 233 } 234 235 class Baz { 236 friend struct ExternCStruct2; 237 friend void ExternCStruct3(); 238 }; 239 240 using namespace namespace_with_injected_name; 241 242 extern "C" { 243 struct ExternCStruct1; 244 struct ExternCStruct2; 245 struct ExternCStruct3; 246 struct ExternCStruct4; // expected-note {{candidate}} 247 } 248 ExternCStruct1 *p1; 249 ExternCStruct2 *p2; 250 ExternCStruct3 *p3; 251 ExternCStruct4 *p4; // expected-error {{ambiguous}} 252 253 extern "C" { 254 struct ExternCStruct1; 255 struct ExternCStruct2; 256 struct ExternCStruct3; 257 struct ExternCStruct4; // expected-note {{candidate}} 258 } 259 ExternCStruct1 *q1 = p1; 260 ExternCStruct2 *q2 = p2; 261 ExternCStruct3 *q3 = p3; 262 ExternCStruct4 *q4 = p4; // expected-error {{ambiguous}} 263 } 264 265 namespace PR35697 { 266 typedef struct {} *ReturnStruct; 267 extern "C" ReturnStruct PR35697_f(); 268 extern "C" ReturnStruct PR35697_v; 269 ReturnStruct PR35697_f(); 270 ReturnStruct PR35697_v; 271 272 namespace { 273 extern "C" ReturnStruct PR35697_f(); 274 extern "C" ReturnStruct PR35697_v; 275 void q() { 276 extern ReturnStruct PR35697_f(); 277 extern ReturnStruct PR35697_v; 278 } 279 } 280 } 281 282 namespace PR46859 { 283 extern "bogus" // expected-error {{unknown linkage language}} 284 template<int> struct X {}; // expected-error {{templates can only be declared in namespace or class scope}} 285 } 286