r244488 - [dllimport] A non-imported class with an imported key can't have a key

[Reid Kleckner via cfe-commits]

Author: rnk
Date: Mon Aug 10 14:39:01 2015
New Revision: 244488

URL: http://llvm.org/viewvc/llvm-project?rev=244488&view=rev
Log:
[dllimport] A non-imported class with an imported key can't have a key

Summary:
The vtable takes its DLL storage class from the class, not the key
function. When they disagree, the vtable won't be exported by the DLL
that defines the key function. The easiest way to ensure that importers
of the class emit their own vtable is to say that the class has no key
function.

Reviewers: hans, majnemer

Subscribers: cfe-commits

Differential Revision: http://reviews.llvm.org/D11913

Modified:
    cfe/trunk/lib/AST/RecordLayoutBuilder.cpp
    cfe/trunk/test/CodeGenCXX/dllimport-rtti.cpp

Modified: cfe/trunk/lib/AST/RecordLayoutBuilder.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/AST/RecordLayoutBuilder.cpp?rev=244488&r1=244487&r2=244488&view=diff
==============================================================================
--- cfe/trunk/lib/AST/RecordLayoutBuilder.cpp (original)
+++ cfe/trunk/lib/AST/RecordLayoutBuilder.cpp Mon Aug 10 14:39:01 2015
@@ -2008,6 +2008,12 @@ static const CXXMethodDecl *computeKeyFu
         continue;
     }
 
+    // If the key function is dllimport but the class isn't, then the class has
+    // no key function. The DLL that exports the key function won't export the
+    // vtable in this case.
+    if (MD->hasAttr<DLLImportAttr>() && !RD->hasAttr<DLLImportAttr>())
+      return nullptr;
+
     // We found it.
     return MD;
   }

Modified: cfe/trunk/test/CodeGenCXX/dllimport-rtti.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenCXX/dllimport-rtti.cpp?rev=244488&r1=244487&r2=244488&view=diff
==============================================================================
--- cfe/trunk/test/CodeGenCXX/dllimport-rtti.cpp (original)
+++ cfe/trunk/test/CodeGenCXX/dllimport-rtti.cpp Mon Aug 10 14:39:01 2015
@@ -22,3 +22,11 @@ struct __declspec(dllimport) V {
 // GNU-DAG: @_ZTV1V = available_externally dllimport
 // GNU-DAG: @_ZTS1V = linkonce_odr
 // GNU-DAG: @_ZTI1V = linkonce_odr
+
+struct W {
+  __declspec(dllimport) virtual void f();
+  virtual void g();
+} w;
+// GNU-DAG: @_ZTV1W = linkonce_odr
+// GNU-DAG: @_ZTS1W = linkonce_odr
+// GNU-DAG: @_ZTI1W = linkonce_odr