2 files changed, 26 insertions, 1 deletions
diff --git a/clang/lib/CodeGen/CGDebugInfo.cpp b/clang/lib/CodeGen/CGDebugInfo.cpp
index 8722e5ae260..ee2e21bdd48 100644
--- a/clang/lib/CodeGen/CGDebugInfo.cpp
+++ b/clang/lib/CodeGen/CGDebugInfo.cpp
@@ -1685,7 +1685,12 @@ static bool shouldOmitDefinition(codegenoptions::DebugInfoKind DebugKind,
   if (!CXXDecl)
     return false;
 
-  if (CXXDecl->hasDefinition() && CXXDecl->isDynamicClass())
+  // Only emit complete debug info for a dynamic class when its vtable is
+  // emitted.  However, Microsoft debuggers don't resolve type information
+  // across DLL boundaries, so skip this optimization if the class is marked
+  // dllimport.
+  if (CXXDecl->hasDefinition() && CXXDecl->isDynamicClass() &&
+      !CXXDecl->hasAttr<DLLImportAttr>())
     return true;
 
   TemplateSpecializationKind Spec = TSK_Undeclared;
diff --git a/clang/test/CodeGenCXX/debug-info-dllimport-base-class.cpp b/clang/test/CodeGenCXX/debug-info-dllimport-base-class.cpp
new file mode 100644
index 00000000000..8b440e14f58
--- /dev/null
+++ b/clang/test/CodeGenCXX/debug-info-dllimport-base-class.cpp
@@ -0,0 +1,20 @@
+// RUN: %clang_cc1 -triple i386-pc-windows -emit-llvm -gcodeview -debug-info-kind=limited -fms-compatibility %s -x c++ -o - | FileCheck %s
+
+// Ensure we emit debug info for the full definition of base classes that will
+// be imported from a DLL.  Otherwise, the debugger wouldn't be able to show the
+// members.
+
+// CHECK: !DICompositeType(tag: DW_TAG_structure_type, name: "ImportedBase",
+// CHECK-NOT:              DIFlagFwdDecl
+// CHECK-SAME:             ){{$}}
+
+struct __declspec(dllimport) ImportedBase {
+  ImportedBase();
+  virtual void Foo();
+};
+
+struct DerivedFromImported : public ImportedBase {};
+
+int main() {
+  DerivedFromImported d;
+}