1 files changed, 13 insertions, 0 deletions
diff --git a/clang/lib/Serialization/ASTWriter.cpp b/clang/lib/Serialization/ASTWriter.cpp
index d335c94861f..7753986d58f 100644
--- a/clang/lib/Serialization/ASTWriter.cpp
+++ b/clang/lib/Serialization/ASTWriter.cpp
@@ -4531,6 +4531,19 @@ void ASTWriter::WriteDeclUpdatesBlocks(RecordDataImpl &OffsetsRecord) {
           auto *Spec = cast<ClassTemplateSpecializationDecl>(RD);
           Record.push_back(Spec->getTemplateSpecializationKind());
           AddSourceLocation(Spec->getPointOfInstantiation(), Record);
+
+          // The instantiation might have been resolved to a partial
+          // specialization. If so, record which one.
+          auto From = Spec->getInstantiatedFrom();
+          if (auto PartialSpec =
+                From.dyn_cast<ClassTemplatePartialSpecializationDecl*>()) {
+            Record.push_back(true);
+            AddDeclRef(PartialSpec, Record);
+            AddTemplateArgumentList(&Spec->getTemplateInstantiationArgs(),
+                                    Record);
+          } else {
+            Record.push_back(false);
+          }
         }
         Record.push_back(RD->getTagKind());
         AddSourceLocation(RD->getLocation(), Record);