Follow-up to r281367: Compare uuids case-insensitively.

llvm-svn: 281430
diff --git a/clang/lib/Sema/SemaDeclAttr.cpp b/clang/lib/Sema/SemaDeclAttr.cpp
index c23db57..a0c0e81 100644
--- a/clang/lib/Sema/SemaDeclAttr.cpp
+++ b/clang/lib/Sema/SemaDeclAttr.cpp
@@ -4607,7 +4607,7 @@
 UuidAttr *Sema::mergeUuidAttr(Decl *D, SourceRange Range,
                               unsigned AttrSpellingListIndex, StringRef Uuid) {
   if (const auto *UA = D->getAttr<UuidAttr>()) {
-    if (UA->getGuid() == Uuid)
+    if (UA->getGuid().equals_lower(Uuid))
       return nullptr;
     Diag(UA->getLocation(), diag::err_mismatched_uuid);
     Diag(Range.getBegin(), diag::note_previous_uuid);