https://bugs.gentoo.org/943712
https://git.savannah.gnu.org/cgit/guile.git/commit/?id=c2e7d834c26dca39e0a2dc6784fc47814969817a

From c2e7d834c26dca39e0a2dc6784fc47814969817a Mon Sep 17 00:00:00 2001
From: Andy Wingo <wingo@pobox.com>
Date: Tue, 25 Jun 2024 09:30:21 +0200
Subject: Fix compilation with C23

* libguile/jit.c (is_unreachable): Rename from "unreachable", which is
apparently a new reserved word in C23.
--- a/libguile/jit.c
+++ b/libguile/jit.c
@@ -370,7 +370,7 @@ set_register_state (scm_jit_state *j, uint32_t state)
 }
 
 static uint32_t
-unreachable (scm_jit_state *j)
+is_unreachable (scm_jit_state *j)
 {
   return j->register_state & UNREACHABLE;
 }
@@ -382,7 +382,7 @@ has_register_state (scm_jit_state *j, uint32_t state)
 }
 
 #define ASSERT_HAS_REGISTER_STATE(state) \
-  ASSERT (unreachable (j) || has_register_state (j, state));
+  ASSERT (is_unreachable (j) || has_register_state (j, state));
 
 static void
 record_gpr_clobber (scm_jit_state *j, jit_gpr_t r)
-- 
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