[CTU] Add more lit tests and better error handling

Summary:
Adding some more CTU list tests. E.g. to check if a construct is unsupported.
We also slightly modify the handling of the return value of the `Import`
function from ASTImporter.

Reviewers: xazax.hun, balazske, a_sidorin

Subscribers: rnkovacs, dkrupp, Szelethus, gamesh411, cfe-commits

Differential Revision: https://reviews.llvm.org/D55131

llvm-svn: 348605

1 files changed, 3 insertions, 1 deletions

diff --git a/clang/lib/CrossTU/CrossTranslationUnit.cpp b/clang/lib/CrossTU/CrossTranslationUnit.cpp
index 7d4f0ec9b42..ec8ac6498ff 100644
--- a/clang/lib/CrossTU/CrossTranslationUnit.cpp
+++ b/clang/lib/CrossTU/CrossTranslationUnit.cpp
@@ -269,7 +269,9 @@ CrossTranslationUnitContext::importDefinition(const FunctionDecl *FD) {
 
   ASTImporter &Importer = getOrCreateASTImporter(FD->getASTContext());
   auto *ToDecl =
-      cast<FunctionDecl>(Importer.Import(const_cast<FunctionDecl *>(FD)));
+      cast_or_null<FunctionDecl>(Importer.Import(const_cast<FunctionDecl *>(FD)));
+  if (!ToDecl)
+    return llvm::make_error<IndexError>(index_error_code::failed_import);
   assert(ToDecl->hasBody());
   assert(FD->hasBody() && "Functions already imported should have body.");
   ++NumGetCTUSuccess;