ActOnTagDefinitionError is supposed to 'unwind' ActOnTagStartDefinition, not
ActOnStartCXXMemberDeclaration.  We haven't started the field collector on this
class yet, so don't stop it.  Fixes a crash in the VS buildbot and a memory error
on all the others.

llvm-svn: 98760
diff --git a/clang/lib/Sema/CXXFieldCollector.h b/clang/lib/Sema/CXXFieldCollector.h
index 69d1351..63c6ee3 100644
--- a/clang/lib/Sema/CXXFieldCollector.h
+++ b/clang/lib/Sema/CXXFieldCollector.h
@@ -58,7 +58,10 @@
   }
 
   /// getCurNumField - The number of fields added to the currently parsed class.
-  size_t getCurNumFields() const { return FieldCount.back(); }
+  size_t getCurNumFields() const {
+    assert(!FieldCount.empty() && "no currently-parsed class");
+    return FieldCount.back();
+  }
 
   /// getCurFields - Pointer to array of fields added to the currently parsed
   /// class.
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index d562a52..19885ba 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -5113,11 +5113,11 @@
 void Sema::ActOnTagDefinitionError(Scope *S, DeclPtrTy TagD) {
   AdjustDeclIfTemplate(TagD);
   TagDecl *Tag = cast<TagDecl>(TagD.getAs<Decl>());
-
   Tag->setInvalidDecl();
 
-  if (isa<CXXRecordDecl>(Tag))
-    FieldCollector->FinishClass();
+  // We're undoing ActOnTagStartDefinition here, not
+  // ActOnStartCXXMemberDeclarations, so we don't have to mess with
+  // the FieldCollector.
 
   PopDeclContext();  
 }