Fix crash when parsing objective-c++ containing invalid lambda

[arphaman]

lib/Parse/ParseExprCXX.cpp

1020

Just to clarify: It seems like this revert (in addition to two TPAs) is the main addition. Did we hit the assertion previously with the crash?

test/Parser/objcxx11-invalid-lambda.cpp

11

Nit: missing newline.

[jkorous-apple]

lib/Parse/ParseExprCXX.cpp

1020

Yes, the crash was done by this assert.
Two TPAs are needed because once TPA is reverted it is not active anymore and cannot be committed. As far as I understand it the assert is not necessary since we are parsing just tentatively and using return value for error signaling.

test/Parser/objcxx11-invalid-lambda.cpp

11

Thanks, will add one.

[jkorous-apple]

newline at the end of test file

[arphaman]

lgtm

lib/Parse/ParseExprCXX.cpp

Optional<unsigned> Parser::ParseLambdaIntroducer(LambdaIntroducer &Intro,
   Intro.Range.setEnd(T.getCloseLocation());
   return DiagResult();
 }
 
 /// TryParseLambdaIntroducer - Tentatively parse a lambda introducer.
 ///
 /// Returns true if it hit something unexpected.
 bool Parser::TryParseLambdaIntroducer(LambdaIntroducer &Intro) {
-  TentativeParsingAction PA(*this);
-
+  {
     bool SkippedInits = false;
-  Optional<unsigned> DiagID(ParseLambdaIntroducer(Intro, &SkippedInits));
+    TentativeParsingAction PA1(*this);
 
-  if (DiagID) {
-    PA.Revert();
+    if (ParseLambdaIntroducer(Intro, &SkippedInits)) {
+      PA1.Revert();
       return true;
     }
 
-  if (SkippedInits) {
-    // Parse it again, but this time parse the init-captures too.
-    PA.Revert();
-    Intro = LambdaIntroducer();
-    DiagID = ParseLambdaIntroducer(Intro);
-    assert(!DiagID && "parsing lambda-introducer failed on reparse");
+    if (!SkippedInits) {
+      PA1.Commit();
       return false;
     }
 
-  PA.Commit();
+    PA1.Revert();
+  }
+
+  // Try to parse it again, but this time parse the init-captures too.
+  Intro = LambdaIntroducer();
+  TentativeParsingAction PA2(*this);
+
+  if (!ParseLambdaIntroducer(Intro)) {
+    PA2.Commit();
     return false;
   }
 
+  PA2.Revert();
+  return true;
+}
+
 static void
 tryConsumeMutableOrConstexprToken(Parser &P, SourceLocation &MutableLoc,
                                   SourceLocation &ConstexprLoc,
                                   SourceLocation &DeclEndLoc) {
   assert(MutableLoc.isInvalid());
   assert(ConstexprLoc.isInvalid());
   // Consume constexpr-opt mutable-opt in any sequence, and set the DeclEndLoc
   // to the final of those locations. Emit an error if we have multiple

test/Parser/objcxx11-invalid-lambda.cpp

+// RUN: %clang_cc1 -fsyntax-only -verify -x objective-c++ -std=c++11 %s
+
+void foo() {  // expected-note {{to match this '{'}}
+  int bar;
+  auto baz = [
+      bar(  // expected-note {{to match this '('}} expected-note {{to match this '('}}
+        foo_undeclared() // expected-error{{use of undeclared identifier 'foo_undeclared'}} expected-error{{use of undeclared identifier 'foo_undeclared'}}
+      /* ) */   
+    ] () { };   // expected-error{{expected ')'}}
+}               // expected-error{{expected ')'}} expected-error{{expected ';' at end of declaration}} expected-error{{expected '}'}}
 No newline at end of file