ignerr: fix unused warning

The ignerr intrinsic macro generates code that has
an unused variable. We fix it by turning it into
a gensym, since unused warnings aren't generated
for gensyms.

* eval.c (unused_arg_s): New static variable.
(me_ignerr): Use the value of unused_arg_s instead
of error_s, for the argument of the catch clause.
(eval_init): gc-protect unused_arg_s.
(eval_late_init): New function in which we initialized
unused_arg_s. The gensym function cannot be used
during eval_init.

* eval.h (eval_late_init): Declared.

* lib.c (init): Call eval_late_init after some other
late initializations.

3 files changed, 11 insertions, 2 deletions

diff --git a/eval.c b/eval.c
index f880232d..e09db92a 100644
--- a/eval.c
+++ b/eval.c
@@ -118,6 +118,7 @@ val iter_item_f, iter_step_f;
 
 val origin_hash;
 
+static val unused_arg_s;
 static val const_foldable_hash;
 
 val make_env(val vbindings, val fbindings, val up_env)
@@ -4414,7 +4415,7 @@ static val me_ignerr(val form, val menv)
 {
   (void) menv;
   return list(catch_s, cons(progn_s, rest(form)),
-              list(error_s, error_s, nao), nao);
+              list(error_s, unused_arg_s, nao), nao);
 }
 
 static val me_whilet(val form, val env)
@@ -6635,7 +6636,8 @@ void eval_init(void)
           &op_table, &pm_table, &last_form_evaled,
           &call_f, &iter_begin_f, &iter_from_binding_f, &iter_more_f,
           &iter_item_f, &iter_step_f,
-          &unbound_s, &origin_hash, &const_foldable_hash, convert(val *, 0));
+          &unbound_s, &origin_hash, &const_foldable_hash,
+          &unused_arg_s, convert(val *, 0));
   top_fb = make_hash(hash_weak_and, nil);
   top_vb = make_hash(hash_weak_and, nil);
   top_mb = make_hash(hash_weak_and, nil);
@@ -7522,6 +7524,11 @@ void eval_init(void)
   autoload_init();
 }
 
+void eval_late_init(void)
+{
+  unused_arg_s = gensym(lit("unused-arg"));
+}
+
 void eval_compat_fixup(int compat_ver)
 {
   if (compat_ver <= 257)
diff --git a/eval.h b/eval.h
index dac4b1c1..a927666f 100644
--- a/eval.h
+++ b/eval.h
@@ -101,4 +101,5 @@ val pprinl(val obj, val stream);
 val tprint(val obj, val out);
 
 void eval_init(void);
+void eval_late_init(void);
 void eval_compat_fixup(int compat_ver);
diff --git a/lib.c b/lib.c
index b3abef2e..f9b6ee30 100644
--- a/lib.c
+++ b/lib.c
@@ -14935,6 +14935,7 @@ void init(val *stack_bottom)
   parse_init();
   uw_late_init();
   less_tab_init();
+  eval_late_init();
 #if HAVE_SYSLOG
   syslog_init();
 #endif