Warn about dllexported explicit class template instantiation declarations (PR22035)

Clang would previously become confused and crash here.

It does not make a lot of sense to export these, so warning seems appropriate.

MSVC will export some member functions for this kind of specializations, whereas
MinGW ignores the dllexport-edness. The latter behaviour seems better.

Differential Revision: http://reviews.llvm.org/D6984

llvm-svn: 226208

1 files changed, 7 insertions, 2 deletions

diff --git a/clang/test/SemaCXX/dllexport.cpp b/clang/test/SemaCXX/dllexport.cpp
index 5d002ac81e5..3bb9d224f72 100644
--- a/clang/test/SemaCXX/dllexport.cpp
+++ b/clang/test/SemaCXX/dllexport.cpp
@@ -353,10 +353,10 @@ ImplicitlyInstantiatedExportedTemplate<IncompleteType> implicitlyInstantiatedExp
 
 // Don't instantiate class members of templates with explicit instantiation declarations, even if they are exported.
 struct IncompleteType2;
-template <typename T> struct __declspec(dllexport) ExportedTemplateWithExplicitInstantiationDecl {
+template <typename T> struct __declspec(dllexport) ExportedTemplateWithExplicitInstantiationDecl { // expected-note{{attribute is here}}
   int f() { return sizeof(T); } // no-error
 };
-extern template struct ExportedTemplateWithExplicitInstantiationDecl<IncompleteType2>;
+extern template struct ExportedTemplateWithExplicitInstantiationDecl<IncompleteType2>; // expected-warning{{explicit instantiation declaration should not be 'dllexport'}}
 
 // Instantiate class members for explicitly instantiated exported templates.
 struct IncompleteType3; // expected-note{{forward declaration of 'IncompleteType3'}}
@@ -386,7 +386,12 @@ template <typename T> struct __declspec(dllexport) ExportedBaseClassTemplateOfEx
 };
 struct __declspec(dllexport) ExportedBaseClass2 : public ExportedBaseClassTemplateOfExportedClass<IncompleteType5> {};
 
+// Warn about explicit instantiation declarations of dllexport classes.
+template <typename T> struct ExplicitInstantiationDeclTemplate {};
+extern template struct __declspec(dllexport) ExplicitInstantiationDeclTemplate<int>; // expected-warning{{explicit instantiation declaration should not be 'dllexport'}} expected-note{{attribute is here}}
 
+template <typename T> struct __declspec(dllexport) ExplicitInstantiationDeclExportedTemplate {}; // expected-note{{attribute is here}}
+extern template struct ExplicitInstantiationDeclExportedTemplate<int>; // expected-warning{{explicit instantiation declaration should not be 'dllexport'}}
 
 //===----------------------------------------------------------------------===//
 // Classes with template base classes