From f87d50f053f3f2f34f92c6001bcdd79a452a3cbf Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Daniel=20Kochma=C5=84ski?= <daniel@turtleware.eu>
Date: Sun, 24 Feb 2019 14:22:13 +0100
Subject: [PATCH] bytecmp: tagbody: ensure ECL_NIL->ECL_NIL_SYMBOL conversion

Issue comes from the fact that list and symbol types are not
disjoint. Fixes #475.

My personal opinion (to put some rambling in a commit message) is that
having NIL being so many things is a blatant mistake and shouldn't be
picked up for Common Lisp (though many programs would probably break
and it wouldn't be so Common then).
---
 src/c/compiler.d | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/src/c/compiler.d b/src/c/compiler.d
index 6c603ca28..43cd27799 100644
--- a/src/c/compiler.d
+++ b/src/c/compiler.d
@@ -1473,6 +1473,9 @@ asm_function(cl_env_ptr env, cl_object function, int flags) {
 static int
 c_go(cl_env_ptr env, cl_object args, int flags) {
   cl_object tag = pop(&args);
+  if (Null(tag)) {
+    tag = ECL_NIL_SYMBOL;
+  }
   cl_object info = c_tag_ref(env, tag, @':tag');
   if (Null(info))
     FEprogram_error("GO: Unknown tag ~S.", 1, tag);
@@ -2060,6 +2063,9 @@ c_tagbody(cl_env_ptr env, cl_object args, int flags)
   /* count the tags */
   for (nt = 0, body = args; !Null(body); ) {
     label = pop(&body);
+    if (Null(label)) {
+      label = ECL_NIL_SYMBOL;
+    }
     item_type = ecl_t_of(label);
     if (item_type == t_symbol || item_type == t_fixnum ||
         item_type == t_bignum) {
@@ -2080,6 +2086,9 @@ c_tagbody(cl_env_ptr env, cl_object args, int flags)
 
   for (body = args; !Null(body); ) {
     label = pop(&body);
+    if (Null(label)) {
+      label = ECL_NIL_SYMBOL;
+    }
     item_type = ecl_t_of(label);
     if (item_type == t_symbol || item_type == t_fixnum ||
         item_type == t_bignum) {