Better parser recovery in Objective-C containers.

Previously it was possible to get an infinite-loop-on-invalid with a namespace
decl within @interface. Since 'namespace' is normally a safe place to retry
top-level parsing, we just didn't consume the token.

This adds a flag that tracks whether we have temporarily left Objective-C
scope to parse a C-like declaration, and uses that to better recover from
parse problems by stopping at possible method declarations and at @end. To
fix the original problem, we do /not/ stop at 'namespace' when in an
Objective-C @interface or @protocol context (but still do in @implementation).

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@159941 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 13 insertions, 2 deletions

diff --git a/include/clang/Parse/Parser.h b/include/clang/Parse/Parser.h
index b9414a4051..14ae6604b2 100644
--- a/include/clang/Parse/Parser.h
+++ b/include/clang/Parse/Parser.h
@@ -23,6 +23,7 @@
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/PrettyStackTrace.h"
+#include "llvm/Support/SaveAndRestore.h"
 #include <stack>
 
 namespace clang {
@@ -83,6 +84,7 @@ class Parser : public CodeCompletionHandler {
   friend class ColonProtectionRAIIObject;
   friend class InMessageExpressionRAIIObject;
   friend class PoisonSEHIdentifiersRAIIObject;
+  friend class ObjCDeclContextSwitch;
   friend class ParenBraceBracketBalancer;
   friend class BalancedDelimiterTracker;
 
@@ -203,6 +205,13 @@ class Parser : public CodeCompletionHandler {
 
   IdentifierInfo *getSEHExceptKeyword();
 
+  /// True if we are within an Objective-C container while parsing C-like decls.
+  ///
+  /// This is necessary because Sema thinks we have left the container
+  /// to parse the C-like decls, meaning Actions.getObjCDeclContext() will
+  /// be NULL.
+  bool ParsingInObjCContainer;
+
   bool SkipFunctionBodies;
 
 public:
@@ -556,9 +565,11 @@ private:
   class ObjCDeclContextSwitch {
     Parser &P;
     Decl *DC;
+    SaveAndRestore<bool> WithinObjCContainer;
   public:
-    explicit ObjCDeclContextSwitch(Parser &p) : P(p),
-               DC(p.getObjCDeclContext()) {
+    explicit ObjCDeclContextSwitch(Parser &p)
+      : P(p), DC(p.getObjCDeclContext()),
+        WithinObjCContainer(P.ParsingInObjCContainer, DC != 0) {
       if (DC)
         P.Actions.ActOnObjCTemporaryExitContainerContext(cast<DeclContext>(DC));
     }