[Clang] Avoid crashes when parsing using enum declarations

In Parser::ParseUsingDeclaration(...) when we call ParseEnumSpecifier(...) it is
not calling SetTypeSpecError() on DS when it detects an error. That means that
DS is left set to TST_unspecified. When we then pass DS into
Sema::ActOnUsingEnumDeclaration(...) we hit an llvm_unreachable(...) since it
expects it to be one of three states TST_error, TST_enum or TST_typename.

This fixes https://github.com/llvm/llvm-project/issues/57347

Differential Revision: https://reviews.llvm.org/D132695

1 files changed, 3 insertions, 0 deletions

diff --git a/clang/lib/Parse/ParseDecl.cpp b/clang/lib/Parse/ParseDecl.cpp
index 97a856a..c502fc5 100644
--- a/clang/lib/Parse/ParseDecl.cpp
+++ b/clang/lib/Parse/ParseDecl.cpp
@@ -4647,6 +4647,7 @@ void Parser::ParseEnumSpecifier(SourceLocation StartLoc, DeclSpec &DS,
 
     if (Spec.isSet() && Tok.isNot(tok::identifier)) {
       Diag(Tok, diag::err_expected) << tok::identifier;
+      DS.SetTypeSpecError();
       if (Tok.isNot(tok::l_brace)) {
         // Has no name and is not a definition.
         // Skip the rest of this declarator, up until the comma or semicolon.
@@ -4663,6 +4664,7 @@ void Parser::ParseEnumSpecifier(SourceLocation StartLoc, DeclSpec &DS,
       Tok.isNot(tok::colon)) {
     Diag(Tok, diag::err_expected_either) << tok::identifier << tok::l_brace;
 
+    DS.SetTypeSpecError();
     // Skip the rest of this declarator, up until the comma or semicolon.
     SkipUntil(tok::comma, StopAtSemi);
     return;
@@ -4838,6 +4840,7 @@ void Parser::ParseEnumSpecifier(SourceLocation StartLoc, DeclSpec &DS,
   if (!Name && TUK != Sema::TUK_Definition) {
     Diag(Tok, diag::err_enumerator_unnamed_no_def);
 
+    DS.SetTypeSpecError();
     // Skip the rest of this declarator, up until the comma or semicolon.
     SkipUntil(tok::comma, StopAtSemi);
     return;