Re-land "[Sema] Make getCurFunction() return null outside function parsing"

This relands r326965.

There was a null dereference in typo correction that was triggered in
Sema/diagnose_if.c. We are not always in a function scope when doing
typo correction. The fix is to add a null check.

LLVM's optimizer made it hard to find this bug. I wrote it up in a
not-very-well-editted blog post here:
http://qinsb.blogspot.com/2018/03/ub-will-delete-your-null-checks.html

llvm-svn: 327334

1 files changed, 1 insertions, 1 deletions

diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index 95b56a242a6..07eb02bec06 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -13126,7 +13126,7 @@ ExprResult Sema::ActOnBlockStmtExpr(SourceLocation CaretLoc,
     for (const auto &CI : Result->getBlockDecl()->captures()) {
       const VarDecl *var = CI.getVariable();
       if (var->getType().isDestructedType() != QualType::DK_none) {
-        getCurFunction()->setHasBranchProtectedScope();
+        setFunctionHasBranchProtectedScope();
         break;
       }
     }