Clean up a large number of C++11 attribute parse issues, including parsing
attributes in more places where we didn't and catching a lot more issues.

This implements nearly every aspect of C++11 attribute parsing, except for:
 - Attributes are permitted on explicit instantiations inside the declarator
   (but not preceding the decl-spec)
 - Attributes are permitted on friend declarations of functions.
 - Multiple instances of the same attribute in an attribute-list (e.g.
   [[noreturn, noreturn]], not [[noreturn]] [[noreturn]] which is conforming)
   are allowed.
The first two are marked as expected-FIXME in the test file and the latter
is probably a defect and is currently untested.

Thanks to Richard Smith for providing the lion's share of the testcases.

llvm-svn: 159072
diff --git a/clang/lib/Parse/ParseStmt.cpp b/clang/lib/Parse/ParseStmt.cpp
index af7d538..5128530 100644
--- a/clang/lib/Parse/ParseStmt.cpp
+++ b/clang/lib/Parse/ParseStmt.cpp
@@ -1259,6 +1259,12 @@
   // Parse the parenthesized condition.
   BalancedDelimiterTracker T(*this, tok::l_paren);
   T.consumeOpen();
+  
+  // FIXME: Do not just parse the attribute contents and throw them away
+  ParsedAttributesWithRange attrs(AttrFactory);
+  MaybeParseCXX0XAttributes(attrs);
+  ProhibitAttributes(attrs);
+
   ExprResult Cond = ParseExpression();
   T.consumeClose();
   DoScope.Exit();
@@ -1347,8 +1353,12 @@
     return StmtError();
   }
 
+  ParsedAttributesWithRange attrs(AttrFactory);
+  MaybeParseCXX0XAttributes(attrs);
+
   // Parse the first part of the for specifier.
   if (Tok.is(tok::semi)) {  // for (;
+    ProhibitAttributes(attrs);
     // no first part, eat the ';'.
     ConsumeToken();
   } else if (isForInitDeclaration()) {  // for (int X = 4;
@@ -1393,6 +1403,7 @@
       Diag(Tok, diag::err_expected_semi_for);
     }
   } else {
+    ProhibitAttributes(attrs);
     Value = ParseExpression();
 
     ForEach = isTokIdentifier_in();