Fix for PR28523: unexpected compilation error.

Clang emits error message for the following code:
```
template <class F> void parallel_loop(F &&f) { f(0); }

int main() {
  int x;
  parallel_loop([&](auto y) {
    {
      x = y;
    };
  });
}
```

$ clang++ --std=gnu++14 clang_test.cc -o clang_test
clang_test.cc:9:7: error: reference to local variable 'x' declared in enclosing function 'main'
      x = y;
            ^
clang_test.cc:2:48: note: in instantiation of function template specialization 'main()::(anonymous class)::operator()<int>' requested here
            template <class F> void parallel_loop(F &&f) { f(0); }
                                                           ^
clang_test.cc:6:3: note: in instantiation of function template specialization 'parallel_loop<(lambda at clang_test.cc:6:17)>' requested here parallel_loop([&](auto y) {
           ^
clang_test.cc:5:7: note: 'x' declared here
      int x;
          ^
1 error generated.

Patch fixes this issue.

llvm-svn: 286584

1 files changed, 13 insertions, 3 deletions

diff --git a/clang/lib/Sema/SemaExprCXX.cpp b/clang/lib/Sema/SemaExprCXX.cpp
index 0dab27affea..634954c3e85 100644
--- a/clang/lib/Sema/SemaExprCXX.cpp
+++ b/clang/lib/Sema/SemaExprCXX.cpp
@@ -6879,8 +6879,14 @@ static void CheckIfAnyEnclosingLambdasMustCaptureAnyPotentialCaptures(
 
   assert(!S.isUnevaluatedContext());
   assert(S.CurContext->isDependentContext());
-  assert(CurrentLSI->CallOperator == S.CurContext &&
+#ifndef NDEBUG
+  DeclContext *DC = S.CurContext;
+  while (DC && isa<CapturedDecl>(DC))
+    DC = DC->getParent();
+  assert(
+      CurrentLSI->CallOperator == DC &&
       "The current call operator must be synchronized with Sema's CurContext");
+#endif // NDEBUG
 
   const bool IsFullExprInstantiationDependent = FE->isInstantiationDependent();
 
@@ -7346,7 +7352,8 @@ ExprResult Sema::ActOnFinishFullExpr(Expr *FE, SourceLocation CC,
   // and then the full-expression +n + ({ 0; }); ends, but it's too late
   // for us to see that we need to capture n after all.
 
-  LambdaScopeInfo *const CurrentLSI = getCurLambda();
+  LambdaScopeInfo *const CurrentLSI =
+      getCurLambda(/*IgnoreCapturedRegions=*/true);
   // FIXME: PR 17877 showed that getCurLambda() can return a valid pointer
   // even if CurContext is not a lambda call operator. Refer to that Bug Report
   // for an example of the code that might cause this asynchrony.
@@ -7361,7 +7368,10 @@ ExprResult Sema::ActOnFinishFullExpr(Expr *FE, SourceLocation CC,
   //     constructor/destructor.
   //  - Teach the handful of places that iterate over FunctionScopes to
   //    stop at the outermost enclosing lexical scope."
-  const bool IsInLambdaDeclContext = isLambdaCallOperator(CurContext);
+  DeclContext *DC = CurContext;
+  while (DC && isa<CapturedDecl>(DC))
+    DC = DC->getParent();
+  const bool IsInLambdaDeclContext = isLambdaCallOperator(DC);
   if (IsInLambdaDeclContext && CurrentLSI &&
       CurrentLSI->hasPotentialCaptures() && !FullExpr.isInvalid())
     CheckIfAnyEnclosingLambdasMustCaptureAnyPotentialCaptures(FE, CurrentLSI,