Index: lib/Sema/SemaDecl.cpp =================================================================== --- lib/Sema/SemaDecl.cpp +++ lib/Sema/SemaDecl.cpp @@ -3560,6 +3560,9 @@ void Sema::setTagNameForLinkagePurposes(TagDecl *TagFromDeclSpec, TypedefNameDecl *NewTD) { + if (TagFromDeclSpec->isInvalidDecl()) + return; + // Do nothing if the tag already has a name for linkage purposes. if (TagFromDeclSpec->hasNameForLinkage()) return; 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}}