From 49e2d9a021a1f969d59d965cd5b97701317e96fa Mon Sep 17 00:00:00 2001
From: Richard Smith <richard-llvm@metafoo.co.uk>
Date: Wed, 8 Jul 2015 21:15:32 +0000
Subject: [PATCH] [modules] Fix crash when writing an update record for a
 redeclaration of an empty namespace.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@241732 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Serialization/ASTWriterDecl.cpp    | 10 ++++++----
 test/Modules/Inputs/namespaces-left.h  |  2 ++
 test/Modules/Inputs/namespaces-right.h |  2 ++
 test/Modules/Inputs/namespaces-top.h   |  2 ++
 4 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/lib/Serialization/ASTWriterDecl.cpp b/lib/Serialization/ASTWriterDecl.cpp
index 371aea8088..cdd8487c55 100644
--- a/lib/Serialization/ASTWriterDecl.cpp
+++ b/lib/Serialization/ASTWriterDecl.cpp
@@ -1016,10 +1016,12 @@ void ASTDeclWriter::VisitNamespaceDecl(NamespaceDecl *D) {
     StoredDeclsMap *Map = NS->buildLookup();
     SmallVector<std::pair<DeclarationName, DeclContext::lookup_result>, 16>
         LookupResults;
-    LookupResults.reserve(Map->size());
-    for (auto &Entry : *Map)
-      LookupResults.push_back(
-          std::make_pair(Entry.first, Entry.second.getLookupResult()));
+    if (Map) {
+      LookupResults.reserve(Map->size());
+      for (auto &Entry : *Map)
+        LookupResults.push_back(
+            std::make_pair(Entry.first, Entry.second.getLookupResult()));
+    }
 
     std::sort(LookupResults.begin(), LookupResults.end(), llvm::less_first());
     for (auto &NameAndResult : LookupResults) {
diff --git a/test/Modules/Inputs/namespaces-left.h b/test/Modules/Inputs/namespaces-left.h
index 787fe753fb..5badf62764 100644
--- a/test/Modules/Inputs/namespaces-left.h
+++ b/test/Modules/Inputs/namespaces-left.h
@@ -71,3 +71,5 @@ namespace N12 {
   }
   Foo *getFoo();
 }
+
+namespace Empty {}
diff --git a/test/Modules/Inputs/namespaces-right.h b/test/Modules/Inputs/namespaces-right.h
index 77f54ead65..dd2ac33f91 100644
--- a/test/Modules/Inputs/namespaces-right.h
+++ b/test/Modules/Inputs/namespaces-right.h
@@ -66,3 +66,5 @@ namespace N12 {
   }
   void consumeFoo(Foo*);
 }
+
+namespace Empty {}
diff --git a/test/Modules/Inputs/namespaces-top.h b/test/Modules/Inputs/namespaces-top.h
index 7bf5394f55..006b53c8fd 100644
--- a/test/Modules/Inputs/namespaces-top.h
+++ b/test/Modules/Inputs/namespaces-top.h
@@ -21,3 +21,5 @@ namespace N13 {
 namespace AddAndReexportBeforeImport {
   int S;
 }
+
+namespace Empty {}
-- 
2.50.1