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, 10 insertions, 2 deletions

diff --git a/clang/lib/Sema/Sema.cpp b/clang/lib/Sema/Sema.cpp
index c2622ecab4b..250e31bc33a 100644
--- a/clang/lib/Sema/Sema.cpp
+++ b/clang/lib/Sema/Sema.cpp
@@ -1201,11 +1201,19 @@ BlockScopeInfo *Sema::getCurBlock() {
   return CurBSI;
 }
 
-LambdaScopeInfo *Sema::getCurLambda() {
+LambdaScopeInfo *Sema::getCurLambda(bool IgnoreCapturedRegions) {
   if (FunctionScopes.empty())
     return nullptr;
 
-  auto CurLSI = dyn_cast<LambdaScopeInfo>(FunctionScopes.back());
+  auto I = FunctionScopes.rbegin();
+  if (IgnoreCapturedRegions) {
+    auto E = FunctionScopes.rend();
+    while (I != E && isa<CapturedRegionScopeInfo>(*I))
+      ++I;
+    if (I == E)
+      return nullptr;
+  }
+  auto *CurLSI = dyn_cast<LambdaScopeInfo>(*I);
   if (CurLSI && CurLSI->Lambda &&
       !CurLSI->Lambda->Encloses(CurContext)) {
     // We have switched contexts due to template instantiation.