Modules: Fix an assertion in DeclContext::buildLookup.

When calling getMostRecentDecl, we can pull in more definitions from
a module. We call getPrimaryContext afterwards to make sure that
we buildLookup on a primary context.

rdar://27926200


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@280728 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 6 insertions, 4 deletions

diff --git a/lib/AST/DeclBase.cpp b/lib/AST/DeclBase.cpp
index 8342c0f2e3..4586d4bd2a 100644
--- a/lib/AST/DeclBase.cpp
+++ b/lib/AST/DeclBase.cpp
@@ -1411,10 +1411,6 @@ DeclContext::lookup(DeclarationName Name) const {
   assert(DeclKind != Decl::LinkageSpec &&
          "Should not perform lookups into linkage specs!");
 
-  const DeclContext *PrimaryContext = getPrimaryContext();
-  if (PrimaryContext != this)
-    return PrimaryContext->lookup(Name);
-
   // If we have an external source, ensure that any later redeclarations of this
   // context have been loaded, since they may add names to the result of this
   // lookup (or add external visible storage).
@@ -1422,6 +1418,12 @@ DeclContext::lookup(DeclarationName Name) const {
   if (Source)
     (void)cast<Decl>(this)->getMostRecentDecl();
 
+  // getMostRecentDecl can change the result of getPrimaryContext. Call
+  // getPrimaryContext afterwards.
+  const DeclContext *PrimaryContext = getPrimaryContext();
+  if (PrimaryContext != this)
+    return PrimaryContext->lookup(Name);
+
   if (hasExternalVisibleStorage()) {
     assert(Source && "external visible storage but no external source?");