Fix a couple of bugs, add some new cool stuff.

1. Fix a todo in Parser::ParseTag, to recover better.  On code like
   that in test/Sema/decl-invalid.c it causes us to return a single
   error instead of multiple.
2. Fix an error in Sema::ParseDeclarator, where it would crash if the
   declarator didn't have an identifier.  Instead, diagnose the problem.
3. Start adding infrastructure to track the range of locations covered
   by a declspec or declarator.  This is mostly implemented for declspec,
   but could be improved, it is missing for declarator.

Thanks to Neil for pointing out this crash.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@40482 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/Preprocessor/macro_rescan2.c b/test/Preprocessor/macro_rescan2.c
new file mode 100644
index 0000000..4fae444
--- /dev/null
+++ b/test/Preprocessor/macro_rescan2.c
@@ -0,0 +1,15 @@
+// RUN: clang %s -E | grep 'a: 2\*f(9)' &&
+// RUN: clang %s -E | grep 'b: 2\*9\*g'
+
+#define f(a) a*g 
+#define g f 
+a: f(2)(9) 
+
+#undef f
+#undef g
+
+#define f(a) a*g 
+#define g(a) f(a) 
+
+b: f(2)(9)
+