Index: lib/Sema/SemaDecl.cpp
===================================================================
--- lib/Sema/SemaDecl.cpp
+++ lib/Sema/SemaDecl.cpp
@@ -3568,7 +3568,8 @@
     return;
 
   // A well-formed anonymous tag must always be a TUK_Definition.
-  assert(TagFromDeclSpec->isThisDeclarationADefinition());
+  if (!TagFromDeclSpec->isThisDeclarationADefinition())
+    return;
 
   // The type must match the tag exactly;  no qualifiers allowed.
   if (!Context.hasSameType(NewTD->getUnderlyingType(),
Index: test/Sema/enum.c
===================================================================
--- test/Sema/enum.c
+++ test/Sema/enum.c
@@ -119,3 +119,7 @@
 
 typedef enum { NegativeShort = (short)-1 } NegativeShortEnum;
 int NegativeShortTest[NegativeShort == -1 ? 1 : -1];
+
+// PR24610
+enum Color { Red, Green, Blue }; // expected-note{{previous use is here}}
+typedef struct Color NewColor; // expected-error {{use of 'Color' with tag type that does not match previous declaration}}