Revert r199416, "MS ABI: Improve selection of an inheritance model"

It broke tests for targeting x86_64-pc-win32:

    Clang Tools :: clang-modernize/LoopConvert/array.cpp
    Clang :: CodeGenCXX/2010-05-10-Var-DbgInfo.cpp
    Clang :: CodeGenCXX/member-call-parens.cpp
    Clang :: CodeGenCXX/ptr-to-datamember.cpp
    Clang :: SemaTemplate/instantiate-function-1.cpp

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@199475 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 29 insertions, 20 deletions

diff --git a/lib/Sema/SemaCast.cpp b/lib/Sema/SemaCast.cpp
index 499e8b18be..63cb15db52 100644
--- a/lib/Sema/SemaCast.cpp
+++ b/lib/Sema/SemaCast.cpp
@@ -21,7 +21,6 @@
 #include "clang/AST/ExprObjC.h"
 #include "clang/AST/RecordLayout.h"
 #include "clang/Basic/PartialDiagnostic.h"
-#include "clang/Basic/TargetInfo.h"
 #include "clang/Sema/Initialization.h"
 #include "llvm/ADT/SmallVector.h"
 #include <set>
@@ -1780,13 +1779,6 @@ static TryCastResult TryReinterpretCast(Sema &Self, ExprResult &SrcExpr,
       return TC_Failed;
     }
 
-    if (Self.Context.getTargetInfo().getCXXABI().isMicrosoft()) {
-      // We need to determine the inheritance model that the class will use if
-      // haven't yet.
-      Self.RequireCompleteType(OpRange.getBegin(), SrcType, 0);
-      Self.RequireCompleteType(OpRange.getBegin(), DestType, 0);
-    }
-
     // Don't allow casting between member pointers of different sizes.
     if (Self.Context.getTypeSize(DestMemPtr) !=
         Self.Context.getTypeSize(SrcMemPtr)) {
diff --git a/lib/Sema/SemaType.cpp b/lib/Sema/SemaType.cpp
index 30edc48dd5..bc674d53d7 100644
--- a/lib/Sema/SemaType.cpp
+++ b/lib/Sema/SemaType.cpp
@@ -1753,6 +1753,35 @@ QualType Sema::BuildMemberPointerType(QualType T, QualType Class,
     return QualType();
   }
 
+  // C++ allows the class type in a member pointer to be an incomplete type.
+  // In the Microsoft ABI, the size of the member pointer can vary
+  // according to the class type, which means that we really need a
+  // complete type if possible, which means we need to instantiate templates.
+  //
+  // If template instantiation fails or the type is just incomplete, we have to
+  // add an extra slot to the member pointer.  Yes, this does cause problems
+  // when passing pointers between TUs that disagree about the size.
+  if (Context.getTargetInfo().getCXXABI().isMicrosoft()) {
+    CXXRecordDecl *RD = Class->getAsCXXRecordDecl();
+    if (RD && !RD->hasAttr<MSInheritanceAttr>()) {
+      // Lock in the inheritance model on the first use of a member pointer.
+      // Otherwise we may disagree about the size at different points in the TU.
+      // FIXME: MSVC picks a model on the first use that needs to know the size,
+      // rather than on the first mention of the type, e.g. typedefs.
+      if (RequireCompleteType(Loc, Class, 0) && !RD->isBeingDefined()) {
+        // We know it doesn't have an attribute and it's incomplete, so use the
+        // unspecified inheritance model.  If we're in the record body, we can
+        // figure out the inheritance model.
+        for (CXXRecordDecl::redecl_iterator I = RD->redecls_begin(),
+             E = RD->redecls_end(); I != E; ++I) {
+          I->addAttr(::new (Context) MSInheritanceAttr(RD->getSourceRange(),
+                                                       Context,
+                                 MSInheritanceAttr::UnspecifiedSpellingIndex));
+        }
+      }
+    }
+  }
+
   // Adjust the default free function calling convention to the default method
   // calling convention.
   if (T->isFunctionType())
@@ -5067,18 +5096,6 @@ bool Sema::RequireCompleteTypeImpl(SourceLocation Loc, QualType T,
       }
     }
 
-    // We lock in the inheritance model once somebody has asked us to ensure
-    // that a pointer-to-member type is complete.
-    if (Context.getTargetInfo().getCXXABI().isMicrosoft()) {
-      if (const MemberPointerType *MPTy = T->getAs<MemberPointerType>()) {
-        if (!MPTy->getClass()->isDependentType()) {
-          RequireCompleteType(Loc, QualType(MPTy->getClass(), 0), 0);
-
-          MPTy->getMostRecentCXXRecordDecl()->setMSInheritanceModel();
-        }
-      }
-    }
-
     return false;
   }