1 files changed, 12 insertions, 1 deletions
diff --git a/lib/Sema/SemaTemplate.cpp b/lib/Sema/SemaTemplate.cpp
index 37eeee2f88676..19c0f2a9390dc 100644
--- a/lib/Sema/SemaTemplate.cpp
+++ b/lib/Sema/SemaTemplate.cpp
@@ -7369,12 +7369,23 @@ Sema::ActOnExplicitInstantiation(Scope *S,
       // FIXME: Need to notify the ASTMutationListener that we did this.
       Def->setTemplateSpecializationKind(TSK);
 
-      if (!getDLLAttr(Def) && getDLLAttr(Specialization)) {
+      if (!getDLLAttr(Def) && getDLLAttr(Specialization) &&
+          Context.getTargetInfo().getCXXABI().isMicrosoft()) {
+        // In the MS ABI, an explicit instantiation definition can add a dll
+        // attribute to a template with a previous instantiation declaration.
+        // MinGW doesn't allow this.
         auto *A = cast<InheritableAttr>(
             getDLLAttr(Specialization)->clone(getASTContext()));
         A->setInherited(true);
         Def->addAttr(A);
         checkClassLevelDLLAttribute(Def);
+
+        // Propagate attribute to base class templates.
+        for (auto &B : Def->bases()) {
+          if (auto *BT = dyn_cast_or_null<ClassTemplateSpecializationDecl>(
+                  B.getType()->getAsCXXRecordDecl()))
+            propagateDLLAttrToBaseClassTemplate(Def, A, BT, B.getLocStart());
+        }
       }
     }