Push DeclGroup much farther throughout the compiler.  Now the various
productions (except the already broken ObjC cases like @class X,Y;) in 
the parser that can produce more than one Decl return a DeclGroup instead
of a Decl, etc.

This allows elimination of the Decl::NextDeclarator field, and exposes
various clients that should look at all decls in a group, but which were
only looking at one (such as the dumper, printer, etc).  These have been
fixed.

Still TODO:

1) there are some FIXME's in the code about potentially using
DeclGroup for better location info.
2) ParseObjCAtDirectives should return a DeclGroup due to @class etc.
3) I'm not sure what is going on with StmtIterator.cpp, or if it can
   be radically simplified now.
4) I put a truly horrible hack in ParseTemplate.cpp.

I plan to bring up #3/4 on the mailing list, but don't plan to tackle
#1/2 in the short term.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@68002 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/tools/clang-cc/Backend.cpp b/tools/clang-cc/Backend.cpp
index 0faabbe..3b3be31 100644
--- a/tools/clang-cc/Backend.cpp
+++ b/tools/clang-cc/Backend.cpp
@@ -8,11 +8,12 @@
 //===----------------------------------------------------------------------===//
 
 #include "ASTConsumers.h"
-#include "clang/AST/ASTContext.h"
-#include "clang/AST/ASTConsumer.h"
-#include "clang/Basic/TargetInfo.h"
 #include "clang/CodeGen/ModuleBuilder.h"
 #include "clang/Frontend/CompileOptions.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/AST/ASTConsumer.h"
+#include "clang/AST/DeclGroup.h"
+#include "clang/Basic/TargetInfo.h"
 #include "llvm/Module.h"
 #include "llvm/ModuleProvider.h"
 #include "llvm/PassManager.h"
@@ -117,13 +118,14 @@
         LLVMIRGeneration.stopTimer();
     }
     
-    virtual void HandleTopLevelDecl(Decl *D) {
-      PrettyStackTraceDecl CrashInfo(D, SourceLocation(),
+    virtual void HandleTopLevelDecl(DeclGroupRef D) {
+      PrettyStackTraceDecl CrashInfo(*D.begin(), SourceLocation(),
                                      Context->getSourceManager(),
                                      "LLVM IR generation of declaration");
+      
       if (CompileOpts.TimePasses)
         LLVMIRGeneration.startTimer();
-      
+
       Gen->HandleTopLevelDecl(D);
 
       if (CompileOpts.TimePasses)