Fix double add_identifier: skip re-registration in doDeclaration for initialized declarators

Co-authored-by: michael-schwarz <13812333+michael-schwarz@users.noreply.github.com>

Author: Copilot

src/frontc/cparser.mly

@@ -123,8 +123,15 @@ let doDeclaration (loc: cabsloc) (specs: spec_elem list) (nl: init_name list) :
     if nl = [] then
       ONLYTYPEDEF (specs, loc)
     else begin
-      (* Tell the lexer about the new variable names *)
-      List.iter (fun ((n, _, _, _), _) -> !Lexerhack.add_identifier n) nl;
+      (* Tell the lexer about the new variable names.
+         For initialized declarations, add_identifier was already called in
+         declarator_init_start before the initializer was parsed (C11 6.2.1.7).
+         Only register names that have no initializer here. *)
+      List.iter (fun ((n, _, _, _), init) ->
+        match init with
+        | NO_INIT -> !Lexerhack.add_identifier n
+        | _ -> ()
+      ) nl;
       DECDEF ((specs, nl), loc)
     end