From eba34ceb258b289a8b01919e127ed508189b28d4 Mon Sep 17 00:00:00 2001
From: Richard Smith <richard-llvm@metafoo.co.uk>
Date: Wed, 12 Sep 2018 02:13:46 +0000
Subject: [PATCH] Fix tracking of merged definitions when the merge target is
 also merged into something else.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@342017 91177308-0d34-0410-b5e6-96231b3b80d8
---
 include/clang/AST/ASTContext.h                |  3 +-
 lib/AST/ASTContext.cpp                        |  4 +--
 .../merge-template-pattern-visibility-2.cpp   | 34 +++++++++++++++++++
 3 files changed, 38 insertions(+), 3 deletions(-)
 create mode 100644 test/Modules/merge-template-pattern-visibility-2.cpp

diff --git a/include/clang/AST/ASTContext.h b/include/clang/AST/ASTContext.h
index d7f32538d7..5b693eb97f 100644
--- a/include/clang/AST/ASTContext.h
+++ b/include/clang/AST/ASTContext.h
@@ -997,7 +997,8 @@ public:
   /// Get the additional modules in which the definition \p Def has
   /// been merged.
   ArrayRef<Module*> getModulesWithMergedDefinition(const NamedDecl *Def) {
-    auto MergedIt = MergedDefModules.find(Def);
+    auto MergedIt =
+        MergedDefModules.find(cast<NamedDecl>(Def->getCanonicalDecl()));
     if (MergedIt == MergedDefModules.end())
       return None;
     return MergedIt->second;
diff --git a/lib/AST/ASTContext.cpp b/lib/AST/ASTContext.cpp
index ab2a95e577..0ed52ffd35 100644
--- a/lib/AST/ASTContext.cpp
+++ b/lib/AST/ASTContext.cpp
@@ -933,13 +933,13 @@ void ASTContext::mergeDefinitionIntoModule(NamedDecl *ND, Module *M,
       Listener->RedefinedHiddenDefinition(ND, M);
 
   if (getLangOpts().ModulesLocalVisibility)
-    MergedDefModules[ND].push_back(M);
+    MergedDefModules[cast<NamedDecl>(ND->getCanonicalDecl())].push_back(M);
   else
     ND->setVisibleDespiteOwningModule();
 }
 
 void ASTContext::deduplicateMergedDefinitonsFor(NamedDecl *ND) {
-  auto It = MergedDefModules.find(ND);
+  auto It = MergedDefModules.find(cast<NamedDecl>(ND->getCanonicalDecl()));
   if (It == MergedDefModules.end())
     return;
 
diff --git a/test/Modules/merge-template-pattern-visibility-2.cpp b/test/Modules/merge-template-pattern-visibility-2.cpp
new file mode 100644
index 0000000000..14577f146e
--- /dev/null
+++ b/test/Modules/merge-template-pattern-visibility-2.cpp
@@ -0,0 +1,34 @@
+// RUN: %clang_cc1 -fmodules -fmodules-local-submodule-visibility %s -verify -Werror=undefined-inline
+
+#pragma clang module build A1
+module A1 { export * }
+#pragma clang module contents
+#pragma clang module begin A1
+template<typename T> class A {};
+template<typename T> inline bool f(const A<T>&) { return T::error; }
+#pragma clang module end
+#pragma clang module endbuild
+
+#pragma clang module build A2
+module A2 { export * }
+#pragma clang module contents
+#pragma clang module begin A2
+#pragma clang module load A1
+template<typename T> class A {};
+template<typename T> inline bool f(const A<T>&) { return T::error; }
+#pragma clang module end
+#pragma clang module endbuild
+
+#pragma clang module build A3
+module A3 { export * }
+#pragma clang module contents
+#pragma clang module begin A3
+template<typename T> class A {};
+template<typename T> inline bool f(const A<T>&) { return T::error; }
+#pragma clang module end
+#pragma clang module endbuild
+
+#pragma clang module load A3
+#pragma clang module import A2
+// expected-error@* {{cannot be used prior to}}
+bool y(A<int> o) { return f(o); } // expected-note {{instantiation of}}
-- 
2.50.1