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      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 definition 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 linkage {
     81   namespace redecl {
     82     extern "C" {
     83       static void linkage_redecl();
     84       static void linkage_redecl(int);
     85       void linkage_redecl(); // ok, still not extern "C"
     86       void linkage_redecl(int); // ok, still not extern "C"
     87       void linkage_redecl(float); // expected-note {{previous}}
     88       void linkage_redecl(double); // expected-error {{conflicting types}}
     89     }
     90   }
     91   namespace from_outer {
     92     void linkage_from_outer_1(); // expected-note {{previous}}
     93     void linkage_from_outer_2(); // expected-note {{previous}}
     94     extern "C" {
     95       void linkage_from_outer_1(int);
     96       void linkage_from_outer_1(); // expected-error {{different language linkage}}
     97       void linkage_from_outer_2(); // expected-error {{different language linkage}}
     98     }
     99   }
    100   namespace mixed {
    101     extern "C" {
    102       void linkage_mixed_1();
    103       static void linkage_mixed_1(int);
    104 
    105       static void linkage_mixed_2(int);
    106       void linkage_mixed_2();
    107     }
    108   }
    109   namespace across_scopes {
    110     namespace X {
    111       extern "C" void linkage_across_scopes_f() {
    112         void linkage_across_scopes_g(); // expected-note {{previous}}
    113       }
    114     }
    115     namespace Y {
    116       extern "C" void linkage_across_scopes_g(int); // expected-error {{conflicting}}
    117     }
    118   }
    119 }
    120 
    121 int lookup_in_global_f; // expected-note {{here}}
    122 namespace lookup_in_global {
    123   void lookup_in_global_f();
    124   void lookup_in_global_g();
    125   extern "C" {
    126     void lookup_in_global_f(int); // expected-error {{conflicts with declaration in global scope}}
    127     void lookup_in_global_g(int); // expected-note {{here}}
    128   }
    129 }
    130 int lookup_in_global_g; // expected-error {{conflicts with declaration with C language linkage}}
    131 
    132 namespace N1 {
    133   extern "C" int different_kind_1; // expected-note {{here}}
    134   extern "C" void different_kind_2(); // expected-note {{here}}
    135 }
    136 namespace N2 {
    137   extern "C" void different_kind_1(); // expected-error {{different kind of symbol}}
    138   extern "C" int different_kind_2; // expected-error {{different kind of symbol}}
    139 }
    140 
    141 // We allow all these even though the standard says they are ill-formed.
    142 extern "C" {
    143   struct stat {};   // expected-warning{{empty struct has size 0 in C, size 1 in C++}}
    144   void stat(struct stat);
    145 }
    146 namespace X {
    147   extern "C" {
    148     void stat(struct ::stat);
    149   }
    150 }
    151 int stat(int *p);
    152 void global_fn_vs_extern_c_var_1();
    153 namespace X {
    154   extern "C" int global_fn_vs_extern_c_var_1;
    155   extern "C" int global_fn_vs_extern_c_var_2;
    156 }
    157 void global_fn_vs_extern_c_var_2();
    158 void global_fn_vs_extern_c_fn_1();
    159 namespace X {
    160   extern "C" int global_fn_vs_extern_c_fn_1(int);
    161   extern "C" int global_fn_vs_extern_c_fn_2(int);
    162 }
    163 void global_fn_vs_extern_c_fn_2();
    164 extern "C" void name_with_using_decl_1(int);
    165 namespace using_decl {
    166   void name_with_using_decl_1();
    167   void name_with_using_decl_2();
    168   void name_with_using_decl_3();
    169 }
    170 using using_decl::name_with_using_decl_1;
    171 using using_decl::name_with_using_decl_2;
    172 extern "C" void name_with_using_decl_2(int);
    173 extern "C" void name_with_using_decl_3(int);
    174 using using_decl::name_with_using_decl_3;
    175 
    176 // We do not allow a global variable and an extern "C" function to have the same
    177 // name, because such entities may have the same mangled name.
    178 int global_var_vs_extern_c_fn_1; // expected-note {{here}}
    179 namespace X {
    180   extern "C" void global_var_vs_extern_c_fn_1(); // expected-error {{conflicts with declaration in global scope}}
    181   extern "C" void global_var_vs_extern_c_fn_2(); // expected-note {{here}}
    182 }
    183 int global_var_vs_extern_c_fn_2; // expected-error {{conflicts with declaration with C language linkage}}
    184 int global_var_vs_extern_c_var_1; // expected-note {{here}}
    185 namespace X {
    186   extern "C" double global_var_vs_extern_c_var_1; // expected-error {{conflicts with declaration in global scope}}
    187   extern "C" double global_var_vs_extern_c_var_2; // expected-note {{here}}
    188 }
    189 int global_var_vs_extern_c_var_2; // expected-error {{conflicts with declaration with C language linkage}}
    190 
    191 template <class T> struct pr5065_n1 {};
    192 extern "C" {
    193   union pr5065_1 {}; // expected-warning{{empty union has size 0 in C, size 1 in C++}}
    194   struct pr5065_2 { int: 0; }; // expected-warning{{struct has size 0 in C, size 1 in C++}}
    195   struct pr5065_3 {}; // expected-warning{{empty struct has size 0 in C, size 1 in C++}}
    196   struct pr5065_4 { // expected-warning{{empty struct has size 0 in C, size 1 in C++}}
    197     struct Inner {}; // expected-warning{{empty struct has size 0 in C, size 1 in C++}}
    198   };
    199   // These should not warn
    200   class pr5065_n3 {};
    201   pr5065_n1<int> pr5065_v;
    202   struct pr5065_n4 { void m() {} };
    203   struct pr5065_n5 : public pr5065_3 {};
    204   struct pr5065_n6 : public virtual pr5065_3 {};
    205 }
    206 struct pr5065_n7 {};
    207