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).

llvm-svn: 159941

2 files changed, 23 insertions, 5 deletions

diff --git a/clang/lib/Parse/ParseDecl.cpp b/clang/lib/Parse/ParseDecl.cpp
index d91457c0d69..05d44a5af0c 100644
--- a/clang/lib/Parse/ParseDecl.cpp
+++ b/clang/lib/Parse/ParseDecl.cpp
@@ -1270,15 +1270,33 @@ void Parser::SkipMalformedDecl() {
 
     case tok::kw_inline:
       // 'inline namespace' at the start of a line is almost certainly
-      // a good place to pick back up parsing.
-      if (Tok.isAtStartOfLine() && NextToken().is(tok::kw_namespace))
+      // a good place to pick back up parsing, except in an Objective-C
+      // @interface context.
+      if (Tok.isAtStartOfLine() && NextToken().is(tok::kw_namespace) &&
+          (!ParsingInObjCContainer || CurParsedObjCImpl))
         return;
       break;
 
     case tok::kw_namespace:
       // 'namespace' at the start of a line is almost certainly a good
-      // place to pick back up parsing.
-      if (Tok.isAtStartOfLine())
+      // place to pick back up parsing, except in an Objective-C
+      // @interface context.
+      if (Tok.isAtStartOfLine() &&
+          (!ParsingInObjCContainer || CurParsedObjCImpl))
+        return;
+      break;
+
+    case tok::at:
+      // @end is very much like } in Objective-C contexts.
+      if (NextToken().isObjCAtKeyword(tok::objc_end) &&
+          ParsingInObjCContainer)
+        return;
+      break;
+
+    case tok::minus:
+    case tok::plus:
+      // - and + probably start new method declarations in Objective-C contexts.
+      if (Tok.isAtStartOfLine() && ParsingInObjCContainer)
         return;
       break;
 
diff --git a/clang/lib/Parse/Parser.cpp b/clang/lib/Parse/Parser.cpp
index 07031338499..d0c988d1dbf 100644
--- a/clang/lib/Parse/Parser.cpp
+++ b/clang/lib/Parse/Parser.cpp
@@ -49,7 +49,7 @@ Parser::Parser(Preprocessor &pp, Sema &actions, bool SkipFunctionBodies)
   : PP(pp), Actions(actions), Diags(PP.getDiagnostics()),
     GreaterThanIsOperator(true), ColonIsSacred(false), 
     InMessageExpression(false), TemplateParameterDepth(0),
-    SkipFunctionBodies(SkipFunctionBodies) {
+    ParsingInObjCContainer(false), SkipFunctionBodies(SkipFunctionBodies) {
   Tok.setKind(tok::eof);
   Actions.CurScope = 0;
   NumCachedScopes = 0;