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

[arphaman]

lib/Parse/ParseExprCXX.cpp

1020 ↗

(On Diff #120813)

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 ↗

(On Diff #120813)

Nit: missing newline.

[jkorous-apple]

lib/Parse/ParseExprCXX.cpp

1020 ↗

(On Diff #120813)

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 ↗

(On Diff #120813)

Thanks, will add one.

[jkorous-apple]

newline at the end of test file

[arphaman]

lgtm

cfe/trunk/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

cfe/trunk/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 '}'}}