C++ DR2387: a variable template declared wtih (or instantiated with) a

const-qualified type is not implicitly given internal linkage. But a
variable template declared 'static' is.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@359048 91177308-0d34-0410-b5e6-96231b3b80d8

9 files changed, 87 insertions, 20 deletions

diff --git a/test/CXX/drs/dr0xx.cpp b/test/CXX/drs/dr0xx.cpp
index 911aab1747..53bd6f3f05 100644
--- a/test/CXX/drs/dr0xx.cpp
+++ b/test/CXX/drs/dr0xx.cpp
@@ -869,18 +869,17 @@ namespace dr68 { // dr68: yes
 }
 
 namespace dr69 { // dr69: yes
-  template<typename T> static void f() {}
+  template<typename T> static void f() {} // #dr69-f
   // FIXME: Should we warn here?
   inline void g() { f<int>(); }
-  // FIXME: This should be rejected, per [temp.explicit]p11.
-  extern template void f<char>();
+  extern template void f<char>(); // expected-error {{explicit instantiation declaration of 'f' with internal linkage}}
 #if __cplusplus < 201103L
   // expected-error@-2 {{C++11 extension}}
 #endif
   template<void(*)()> struct Q {};
   Q<&f<int> > q;
 #if __cplusplus < 201103L
-  // expected-error@-2 {{internal linkage}} expected-note@-11 {{here}}
+  // expected-error@-2 {{internal linkage}} expected-note@#dr69-f {{here}}
 #endif
 }
 
diff --git a/test/CXX/drs/dr17xx.cpp b/test/CXX/drs/dr17xx.cpp
index 9f67b24271..bf7458ea81 100644
--- a/test/CXX/drs/dr17xx.cpp
+++ b/test/CXX/drs/dr17xx.cpp
@@ -77,7 +77,7 @@ namespace dr1758 { // dr1758: 3.7
 #endif
 }
 
-namespace dr1722 { // dr1722: 9.0
+namespace dr1722 { // dr1722: 9
 #if __cplusplus >= 201103L
 void f() {
   const auto lambda = [](int x) { return x + 1; };
diff --git a/test/CXX/drs/dr23xx.cpp b/test/CXX/drs/dr23xx.cpp
new file mode 100644
index 0000000000..87db0d4c9b
--- /dev/null
+++ b/test/CXX/drs/dr23xx.cpp
@@ -0,0 +1,26 @@
+// RUN: %clang_cc1 -std=c++98 %s -verify -fexceptions -fcxx-exceptions -pedantic-errors
+// RUN: %clang_cc1 -std=c++11 %s -verify -fexceptions -fcxx-exceptions -pedantic-errors
+// RUN: %clang_cc1 -std=c++14 %s -verify -fexceptions -fcxx-exceptions -pedantic-errors
+// RUN: %clang_cc1 -std=c++17 %s -verify -fexceptions -fcxx-exceptions -pedantic-errors
+// RUN: %clang_cc1 -std=c++2a %s -verify -fexceptions -fcxx-exceptions -pedantic-errors
+
+#if __cplusplus <= 201103L
+// expected-no-diagnostics
+#endif
+
+namespace dr2387 { // dr2387: 9
+#if __cplusplus >= 201402L
+  template<int> int a = 0;
+  extern template int a<0>; // ok
+
+  template<int> static int b = 0;
+  extern template int b<0>; // expected-error {{internal linkage}}
+
+  template<int> const int c = 0;
+  extern template const int c<0>; // ok, has external linkage despite 'const'
+
+  template<typename T> T d = 0;
+  extern template int d<int>;
+  extern template const int d<const int>;
+#endif
+}
diff --git a/test/CXX/module/module.interface/p3.cpp b/test/CXX/module/module.interface/p3.cpp
index 89c5e08f54..22a003550b 100644
--- a/test/CXX/module/module.interface/p3.cpp
+++ b/test/CXX/module/module.interface/p3.cpp
@@ -48,7 +48,7 @@ export namespace { int c; } // expected-error {{declaration of 'c' with internal
 namespace { // expected-note {{here}}
   export int d; // expected-error {{export declaration appears within anonymous namespace}}
 }
-export template<typename> static int e; // FIXME
+export template<typename> static int e; // expected-error {{declaration of 'e' with internal linkage cannot be exported}}
 export template<typename> static int f(); // expected-error {{declaration of 'f' with internal linkage cannot be exported}}
 export const int k = 5;
 export static union { int n; }; // expected-error {{declaration of 'n' with internal linkage cannot be exported}}
diff --git a/test/CXX/module/module.interface/p5.cpp b/test/CXX/module/module.interface/p5.cpp
index c4299dc04f..17c4105baa 100644
--- a/test/CXX/module/module.interface/p5.cpp
+++ b/test/CXX/module/module.interface/p5.cpp
@@ -14,7 +14,7 @@ static union { int sg1, sg2; }; // expected-note {{target}}
 namespace NS {}
 
 template<typename> int ta;
-template<typename> static int sta;
+template<typename> static int sta; // expected-note {{target}}
 template<typename> void tb();
 template<typename> static void stb(); // expected-note {{target}}
 template<typename> struct tc {};
@@ -44,7 +44,7 @@ namespace UnnamedNS {
   }
 }
 
-export { // expected-note 18{{here}}
+export { // expected-note 19{{here}}
   using ::a;
   using ::sa; // expected-error {{using declaration referring to 'sa' with internal linkage}}
   using ::b;
@@ -56,7 +56,7 @@ export { // expected-note 18{{here}}
   using ::sg1; // expected-error {{using declaration referring to 'sg1' with internal linkage}}
 
   using ::ta;
-  using ::sta; // FIXME {{using declaration referring to 'sta' with internal linkage}}
+  using ::sta; // expected-error {{using declaration referring to 'sta' with internal linkage}}
   using ::tb;
   using ::stb; // expected-error {{using declaration referring to 'stb' with internal linkage}}
   using ::tc;
diff --git a/test/CodeGenCXX/cxx1y-variable-template-linkage.cpp b/test/CodeGenCXX/cxx1y-variable-template-linkage.cpp
index bc775568aa..c77841cabc 100644
--- a/test/CodeGenCXX/cxx1y-variable-template-linkage.cpp
+++ b/test/CodeGenCXX/cxx1y-variable-template-linkage.cpp
@@ -6,21 +6,61 @@
 // should be 'internal global' and not 'linkonce_odr global'.
 
 template <typename T> int x = 42;
-
+// CHECK-DAG: @_Z1xIiE = linkonce_odr global
 // CHECK-DAG: @_Z1xIZL3foovE3FooE = internal global
 
+// 'static' affects the linkage of the global
+template <typename T> static int y = 42;
+// CHECK-DAG: @_ZL1yIiE = internal global
+// CHECK-DAG: @_ZL1yIZL3foovE3FooE = internal global
+
+// 'const' does not
+template <typename T> const int z = 42;
+// CHECK-DAG: @_Z1zIiE = linkonce_odr constant
+// CHECK-DAG: @_Z1zIZL3foovE3FooE = internal constant
+
+template <typename T> T t = 42;
+// CHECK-DAG: @_Z1tIiE = linkonce_odr global
+// CHECK-DAG: @_Z1tIKiE = linkonce_odr constant
+
+int mode;
+
 // CHECK-DAG: define internal dereferenceable(4) i32* @_ZL3foov(
-static int &foo() {
+static const int &foo() {
    struct Foo { };
-   
-   // CHECK-DAG: ret i32* @_Z1xIZL3foovE3FooE
-   return x<Foo>;
+
+   switch (mode) {
+   case 0:
+     // CHECK-DAG: @_Z1xIiE
+     return x<int>;
+   case 1:
+     // CHECK-DAG: @_Z1xIZL3foovE3FooE
+     return x<Foo>;
+   case 2:
+     // CHECK-DAG: @_ZL1yIiE
+     return y<int>;
+   case 3:
+     // CHECK-DAG: @_ZL1yIZL3foovE3FooE
+     return y<Foo>;
+   case 4:
+     // CHECK-DAG: @_Z1zIiE
+     return z<int>;
+   case 5:
+     // CHECK-DAG: @_Z1zIZL3foovE3FooE
+     return z<Foo>;
+   case 6:
+     // CHECK-DAG: @_Z1tIiE
+     return t<int>;
+   case 7:
+     // CHECK-DAG: @_Z1tIKiE
+     return t<const int>;
+   }
 }
 
 
 #if !__has_feature(cxx_exceptions) // File A
 // CHECKA-DAG: define dereferenceable(4) i32* @_Z3barv(
-int &bar() { 
+const int &bar() {
 	// CHECKA-DAG: call dereferenceable(4) i32* @_ZL3foov()
 	return foo();
 }
@@ -28,7 +68,7 @@ int &bar() {
 #else // File B
 
 // CHECKB-DAG: declare dereferenceable(4) i32* @_Z3barv(
-int &bar();
+const int &bar();
 
 int main() {
 	// CHECKB-DAG: call dereferenceable(4) i32* @_Z3barv()
diff --git a/test/SemaCXX/PR10177.cpp b/test/SemaCXX/PR10177.cpp
index 59630be508..0d2e792f52 100644
--- a/test/SemaCXX/PR10177.cpp
+++ b/test/SemaCXX/PR10177.cpp
@@ -57,11 +57,10 @@ namespace N {
 }
 
 #else
-// expected-no-diagnostics
 
 namespace { template<typename> extern int n; }
 template<typename T> int g() { return n<int>; }
-namespace { extern template int n<int>; }
+namespace { extern template int n<int>; } // expected-error {{explicit instantiation declaration of 'n<int>' with internal linkage}}
 
 #endif
 
diff --git a/test/SemaCXX/warn-unused-filescoped.cpp b/test/SemaCXX/warn-unused-filescoped.cpp
index 93c6bbd7ed..e052ecb1af 100644
--- a/test/SemaCXX/warn-unused-filescoped.cpp
+++ b/test/SemaCXX/warn-unused-filescoped.cpp
@@ -207,8 +207,9 @@ static void completeRedeclChainForTemplateSpecialization() { } // expected-warni
 
 namespace test10 {
 #if __cplusplus >= 201103L
+// FIXME: Warn on template definitions with no instantiations?
 template<class T>
-constexpr T pi = T(3.14); // expected-warning {{unused}}
+constexpr T pi = T(3.14);
 #endif
 }
 
diff --git a/test/SemaCXX/warn-unused-variables.cpp b/test/SemaCXX/warn-unused-variables.cpp
index a7ac9afc36..97634ac43c 100644
--- a/test/SemaCXX/warn-unused-variables.cpp
+++ b/test/SemaCXX/warn-unused-variables.cpp
@@ -135,7 +135,9 @@ namespace PR19305 {
   template<typename T> int m = 0;
   template<typename T> int m<T*> = 0;
 
-  template<> const int m<void> = 0; // expected-warning {{unused variable}}
+  // This has external linkage, so could be referenced by a declaration in a
+  // different translation unit.
+  template<> const int m<void> = 0; // no warning
 }
 
 namespace ctor_with_cleanups {