1 files changed, 65 insertions, 57 deletions

diff --git a/lib/Sema/SemaDeclCXX.cpp b/lib/Sema/SemaDeclCXX.cpp
index b1dfe0e..c80ef2d 100644
--- a/lib/Sema/SemaDeclCXX.cpp
+++ b/lib/Sema/SemaDeclCXX.cpp
@@ -1345,57 +1345,6 @@ static bool findCircularInheritance(const CXXRecordDecl *Class,
   return false;
 }
 
-/// \brief Perform propagation of DLL attributes from a derived class to a
-/// templated base class for MS compatibility.
-static void propagateDLLAttrToBaseClassTemplate(
-    Sema &S, CXXRecordDecl *Class, Attr *ClassAttr,
-    ClassTemplateSpecializationDecl *BaseTemplateSpec, SourceLocation BaseLoc) {
-  if (getDLLAttr(
-          BaseTemplateSpec->getSpecializedTemplate()->getTemplatedDecl())) {
-    // If the base class template has a DLL attribute, don't try to change it.
-    return;
-  }
-
-  if (BaseTemplateSpec->getSpecializationKind() == TSK_Undeclared) {
-    // If the base class is not already specialized, we can do the propagation.
-    auto *NewAttr = cast<InheritableAttr>(ClassAttr->clone(S.getASTContext()));
-    NewAttr->setInherited(true);
-    BaseTemplateSpec->addAttr(NewAttr);
-    return;
-  }
-
-  bool DifferentAttribute = false;
-  if (Attr *SpecializationAttr = getDLLAttr(BaseTemplateSpec)) {
-    if (!SpecializationAttr->isInherited()) {
-      // The template has previously been specialized or instantiated with an
-      // explicit attribute. We should not try to change it.
-      return;
-    }
-    if (SpecializationAttr->getKind() == ClassAttr->getKind()) {
-      // The specialization already has the right attribute.
-      return;
-    }
-    DifferentAttribute = true;
-  }
-
-  // The template was previously instantiated or explicitly specialized without
-  // a dll attribute, or the template was previously instantiated with a
-  // different inherited attribute. It's too late for us to change the
-  // attribute, so warn that this is unsupported.
-  S.Diag(BaseLoc, diag::warn_attribute_dll_instantiated_base_class)
-      << BaseTemplateSpec->isExplicitSpecialization() << DifferentAttribute;
-  S.Diag(ClassAttr->getLocation(), diag::note_attribute);
-  if (BaseTemplateSpec->isExplicitSpecialization()) {
-    S.Diag(BaseTemplateSpec->getLocation(),
-           diag::note_template_class_explicit_specialization_was_here)
-        << BaseTemplateSpec;
-  } else {
-    S.Diag(BaseTemplateSpec->getPointOfInstantiation(),
-           diag::note_template_class_instantiation_was_here)
-        << BaseTemplateSpec;
-  }
-}
-
 /// \brief Check the validity of a C++ base class specifier.
 ///
 /// \returns a new CXXBaseSpecifier if well-formed, emits diagnostics
@@ -1467,8 +1416,8 @@ Sema::CheckBaseSpecifier(CXXRecordDecl *Class,
     if (Attr *ClassAttr = getDLLAttr(Class)) {
       if (auto *BaseTemplate = dyn_cast_or_null<ClassTemplateSpecializationDecl>(
               BaseType->getAsCXXRecordDecl())) {
-        propagateDLLAttrToBaseClassTemplate(*this, Class, ClassAttr,
-                                            BaseTemplate, BaseLoc);
+        propagateDLLAttrToBaseClassTemplate(Class, ClassAttr, BaseTemplate,
+                                            BaseLoc);
       }
     }
   }
@@ -4791,8 +4740,9 @@ void Sema::checkClassLevelDLLAttribute(CXXRecordDecl *Class) {
 
   TemplateSpecializationKind TSK = Class->getTemplateSpecializationKind();
 
-  // Don't dllexport explicit class template instantiation declarations.
-  if (ClassExported && TSK == TSK_ExplicitInstantiationDeclaration) {
+  // Ignore explicit dllexport on explicit class template instantiation declarations.
+  if (ClassExported && !ClassAttr->isInherited() &&
+      TSK == TSK_ExplicitInstantiationDeclaration) {
     Class->dropAttr<DLLExportAttr>();
     return;
   }
@@ -4840,12 +4790,15 @@ void Sema::checkClassLevelDLLAttribute(CXXRecordDecl *Class) {
     }
 
     if (MD && ClassExported) {
+      if (TSK == TSK_ExplicitInstantiationDeclaration)
+        // Don't go any further if this is just an explicit instantiation
+        // declaration.
+        continue;
+
       if (MD->isUserProvided()) {
         // Instantiate non-default class member functions ...
 
         // .. except for certain kinds of template specializations.
-        if (TSK == TSK_ExplicitInstantiationDeclaration)
-          continue;
         if (TSK == TSK_ImplicitInstantiation && !ClassAttr->isInherited())
           continue;
 
@@ -4876,6 +4829,61 @@ void Sema::checkClassLevelDLLAttribute(CXXRecordDecl *Class) {
   }
 }
 
+/// \brief Perform propagation of DLL attributes from a derived class to a
+/// templated base class for MS compatibility.
+void Sema::propagateDLLAttrToBaseClassTemplate(
+    CXXRecordDecl *Class, Attr *ClassAttr,
+    ClassTemplateSpecializationDecl *BaseTemplateSpec, SourceLocation BaseLoc) {
+  if (getDLLAttr(
+          BaseTemplateSpec->getSpecializedTemplate()->getTemplatedDecl())) {
+    // If the base class template has a DLL attribute, don't try to change it.
+    return;
+  }
+
+  auto TSK = BaseTemplateSpec->getSpecializationKind();
+  if (!getDLLAttr(BaseTemplateSpec) &&
+      (TSK == TSK_Undeclared || TSK == TSK_ExplicitInstantiationDeclaration ||
+       TSK == TSK_ImplicitInstantiation)) {
+    // The template hasn't been instantiated yet (or it has, but only as an
+    // explicit instantiation declaration or implicit instantiation, which means
+    // we haven't codegenned any members yet), so propagate the attribute.
+    auto *NewAttr = cast<InheritableAttr>(ClassAttr->clone(getASTContext()));
+    NewAttr->setInherited(true);
+    BaseTemplateSpec->addAttr(NewAttr);
+
+    // If the template is already instantiated, checkDLLAttributeRedeclaration()
+    // needs to be run again to work see the new attribute. Otherwise this will
+    // get run whenever the template is instantiated.
+    if (TSK != TSK_Undeclared)
+      checkClassLevelDLLAttribute(BaseTemplateSpec);
+
+    return;
+  }
+
+  if (getDLLAttr(BaseTemplateSpec)) {
+    // The template has already been specialized or instantiated with an
+    // attribute, explicitly or through propagation. We should not try to change
+    // it.
+    return;
+  }
+
+  // The template was previously instantiated or explicitly specialized without
+  // a dll attribute, It's too late for us to add an attribute, so warn that
+  // this is unsupported.
+  Diag(BaseLoc, diag::warn_attribute_dll_instantiated_base_class)
+      << BaseTemplateSpec->isExplicitSpecialization();
+  Diag(ClassAttr->getLocation(), diag::note_attribute);
+  if (BaseTemplateSpec->isExplicitSpecialization()) {
+    Diag(BaseTemplateSpec->getLocation(),
+           diag::note_template_class_explicit_specialization_was_here)
+        << BaseTemplateSpec;
+  } else {
+    Diag(BaseTemplateSpec->getPointOfInstantiation(),
+           diag::note_template_class_instantiation_was_here)
+        << BaseTemplateSpec;
+  }
+}
+
 /// \brief Perform semantic checks on a class definition that has been
 /// completing, introducing implicitly-declared members, checking for
 /// abstract types, etc.