clang/test/Modules/redecl-templates.cpp

   1 // RUN: rm -rf %t
   2 // RUN: %clang_cc1 -x c++ -I %S/Inputs/redecl-templates %s -verify -std=c++14
   3 // RUN: %clang_cc1 -x c++ -fmodules -fimplicit-module-maps -fmodules-cache-path=%t -I %S/Inputs/redecl-templates %s -verify -std=c++14
   4
   5 template<int N> struct A {};
   6 template<int N> using X = A<N>;
   7
   8 template<int N> constexpr void f() {}
   9 template<int N> constexpr void g() { f<N>(); }
  10
  11 template<int N> extern int v;
  12 template<int N> int &w = v<N>;
  13
  14 #include "a.h"
  15
  16 // Be careful not to mention A here, that'll import the decls from "a.h".
  17 int g(X<1> *);
  18 X<1> *p = 0;
  19
  20 // This will implicitly instantiate A<1> if we haven't imported the explicit
  21 // specialization declaration from "a.h".
  22 int k = g(p);
  23 // Likewise for f and v.
  24 void h() { g<1>(); }
  25 int &x = w<1>;
  26
  27 // This is OK: we declared the explicit specialization before we triggered
  28 // instantiation of this specialization.
  29 template<> struct A<1> {};
  30 template<> constexpr void f<1>() {}
  31 // Variable template explicit specializations are always definitions unless they
  32 // are static data members declared without an initializer.
  33 template<> int v<1>; // expected-error {{redefinition of 'v<1>'}}
  34                      // expected-note@Inputs/redecl-templates/a.h:8 {{previous definition is here}}