1 // RUN: %clang_cc1 -fsyntax-only -verify -std=c++1y %s
2 
3 // expected-no-diagnostics
4 
5 // C++11 [basic.link]p6:
6 //   The name of a function declared in block scope and the name
7 //   of a variable declared by a block scope extern declaration
8 //   have linkage. If there is a visible declaration of an entity
9 //   with linkage having the same name and type, ignoring entities
10 //   declared outside the innermost enclosing namespace scope, the
11 //   block scope declaration declares that same entity and
12 //   receives the linkage of the previous declaration.
13 
14 extern int same_entity;
15 constexpr int *get1() {
16   int same_entity = 0; // not the same entity
17   {
18     extern int same_entity;
19     return &same_entity;
20   }
21 }
22 static_assert(get1() == &same_entity, "failed to find previous decl");
23 
24 static int same_entity_2[3];
25 constexpr int *get2() {
26   // This is a redeclaration of the same entity, even though it doesn't
27   // inherit the type of the prior declaration.
28   extern int same_entity_2[];
29   return same_entity_2;
30 }
31 static_assert(get2() == same_entity_2, "failed to find previous decl");
32 
33 static int different_entities;
34 constexpr int *get3() {
35   int different_entities = 0;
36   {
37     // FIXME: This is not a redeclaration of the prior entity, because
38     // it is not visible here. Under DR426, this is ill-formed, and without
39     // it, the static_assert below should fail.
40     extern int different_entities;
41     return &different_entities;
42   }
43 }
44 static_assert(get3() == &different_entities, "failed to find previous decl");
45