4 files changed, 19 insertions, 2 deletions
diff --git a/clang/lib/Serialization/ASTReaderDecl.cpp b/clang/lib/Serialization/ASTReaderDecl.cpp
index 3ac67071f0d..4f1c4ec6915 100644
--- a/clang/lib/Serialization/ASTReaderDecl.cpp
+++ b/clang/lib/Serialization/ASTReaderDecl.cpp
@@ -2548,7 +2548,9 @@ ASTDeclReader::FindExistingResult ASTDeclReader::findExisting(NamedDecl *D) {
   //
   // FIXME: We should do something similar if we merge two definitions of the
   // same template specialization into the same CXXRecordDecl.
-  if (Reader.MergedDeclContexts.count(D->getLexicalDeclContext()))
+  auto MergedDCIt = Reader.MergedDeclContexts.find(D->getLexicalDeclContext());
+  if (MergedDCIt != Reader.MergedDeclContexts.end() &&
+      MergedDCIt->second == D->getDeclContext())
     Reader.PendingOdrMergeChecks.push_back(D);
 
   return FindExistingResult(Reader, D, /*Existing=*/nullptr);
diff --git a/clang/test/Modules/Inputs/odr/a.h b/clang/test/Modules/Inputs/odr/a.h
index 26144b86e8d..5a3f5240948 100644
--- a/clang/test/Modules/Inputs/odr/a.h
+++ b/clang/test/Modules/Inputs/odr/a.h
@@ -8,6 +8,12 @@ struct X {
   int n;
 } x1;
 
+template<typename T>
+struct F {
+  int n;
+  friend bool operator==(const F &a, const F &b) { return a.n == b.n; }
+};
+
 int f() {
   return y1.n + e1 + y1.f + x1.n;
 }
diff --git a/clang/test/Modules/Inputs/odr/b.h b/clang/test/Modules/Inputs/odr/b.h
index b4063979474..a4a693df2bf 100644
--- a/clang/test/Modules/Inputs/odr/b.h
+++ b/clang/test/Modules/Inputs/odr/b.h
@@ -4,6 +4,12 @@ struct Y {
 } y2;
 enum E { e2 };
 
+template<typename T>
+struct F {
+  int n;
+  friend bool operator==(const F &a, const F &b) { return a.n == b.n; }
+};
+
 int g() {
-  return y2.m + e2 + y2.f;
+  return y2.m + e2 + y2.f + (F<int>{0} == F<int>{1});
 }
diff --git a/clang/test/Modules/odr.cpp b/clang/test/Modules/odr.cpp
index 5ab10d2ce41..120ca20e0a8 100644
--- a/clang/test/Modules/odr.cpp
+++ b/clang/test/Modules/odr.cpp
@@ -6,6 +6,9 @@ struct X { // expected-note {{definition has no member 'n'}}
 };
 
 @import a;
+
+bool b = F<int>{0} == F<int>{1};
+
 @import b;
 
 // Trigger the declarations from a and b to be imported.