Permit duplicate explicit class instantiations if MSVCCompat is enabled

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@208402 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/clang/Basic/DiagnosticSemaKinds.td b/include/clang/Basic/DiagnosticSemaKinds.td
index e33d2c16666952e0b6bb74671dddf75b627ed463..4b9b722770f9cd656c4f5831df78ebf950f7130e 100644 (file)
--- a/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/include/clang/Basic/DiagnosticSemaKinds.td
@@ -3396,6 +3396,9 @@ def err_nested_name_spec_non_tag : Error<
 // C++ Explicit Instantiation
 def err_explicit_instantiation_duplicate : Error<
     "duplicate explicit instantiation of %0">;
+def warn_explicit_instantiation_duplicate : ExtWarn<
+    "duplicate explicit instantiation of %0 ignored as a Microsoft extension">,
+    InGroup<Microsoft>;
 def note_previous_explicit_instantiation : Note<
     "previous explicit instantiation is here">;
 def ext_explicit_instantiation_after_specialization : Extension<

diff --git a/lib/Sema/SemaTemplate.cpp b/lib/Sema/SemaTemplate.cpp
index 8c0261381c1dc6b41c5b2c780cb12e8ac0192dec..dd2faf60d4a726b94a37ddff95c106ab84f8fc89 100644 (file)
--- a/lib/Sema/SemaTemplate.cpp
+++ b/lib/Sema/SemaTemplate.cpp
@@ -6526,8 +6526,12 @@ Sema::CheckSpecializationInstantiationRedecl(SourceLocation NewLoc,
       //   For a given template and a given set of template-arguments,
       //     - an explicit instantiation definition shall appear at most once
       //       in a program,
-      Diag(NewLoc, diag::err_explicit_instantiation_duplicate)
-        << PrevDecl;
+
+      // MSVCCompat: MSVC silently ignores duplicate explicit instantiations.
+      Diag(NewLoc, (getLangOpts().MSVCCompat)
+                       ? diag::warn_explicit_instantiation_duplicate
+                       : diag::err_explicit_instantiation_duplicate)
+          << PrevDecl;
       Diag(DiagLocForExplicitInstantiation(PrevDecl, PrevPointOfInstantiation),
            diag::note_previous_explicit_instantiation);
       HasNoEffect = true;

diff --git a/test/SemaTemplate/ms-class-specialization-duplicate.cpp b/test/SemaTemplate/ms-class-specialization-duplicate.cpp
new file mode 100644 (file)
index 0000000..183fdfc
--- /dev/null
+++ b/test/SemaTemplate/ms-class-specialization-duplicate.cpp
@@ -0,0 +1,9 @@
+// RUN: %clang_cc1 -fms-compatibility -fdelayed-template-parsing -fsyntax-only -verify %s
+
+template <typename T>
+class A {
+};
+typedef int TInt;
+
+template class A<int>;  // expected-note {{previous explicit instantiation is here}}
+template class A<TInt>; // expected-warning {{duplicate explicit instantiation of 'A<int>' ignored as a Microsoft extension}}