[ASTImporter] Added error handling for AST import.

Summary:
The goal of this change is to make the ASTImporter::Import functions return
llvm::Expected instead of the imported type.
As first part the ASTNodeImporter visit functions are updated to return with
llvm::Expected. Various `import` functions are added to ASTNodeImporter to
simplify the code and have a common place for interface towards ASTImporter
(from ASTNodeImporter). There is some temporary code that is needed before
ASTImporter is updated.

Reviewers: a.sidorin, a_sidorin, xazax.hun

Reviewed By: a_sidorin

Subscribers: dkrupp, Szelethus, rnkovacs, martong, jfb, cfe-commits

Differential Revision: https://reviews.llvm.org/D51633

llvm-svn: 344783

1 files changed, 4 insertions, 2 deletions

diff --git a/clang/lib/AST/ExternalASTMerger.cpp b/clang/lib/AST/ExternalASTMerger.cpp
index ae28c588ca3..e7ca3ac1459 100644
--- a/clang/lib/AST/ExternalASTMerger.cpp
+++ b/clang/lib/AST/ExternalASTMerger.cpp
@@ -230,7 +230,8 @@ void ExternalASTMerger::CompleteType(TagDecl *Tag) {
     if (!SourceTag->getDefinition())
       return false;
     Forward.MapImported(SourceTag, Tag);
-    Forward.ImportDefinition(SourceTag);
+    if (llvm::Error Err = Forward.ImportDefinition_New(SourceTag))
+      llvm::consumeError(std::move(Err));
     Tag->setCompleteDefinition(SourceTag->isCompleteDefinition());
     return true;
   });
@@ -249,7 +250,8 @@ void ExternalASTMerger::CompleteType(ObjCInterfaceDecl *Interface) {
         if (!SourceInterface->getDefinition())
           return false;
         Forward.MapImported(SourceInterface, Interface);
-        Forward.ImportDefinition(SourceInterface);
+        if (llvm::Error Err = Forward.ImportDefinition_New(SourceInterface))
+          llvm::consumeError(std::move(Err));
         return true;
       });
 }