From c83741eb06032940cd6f790356df68fb48974d18 Mon Sep 17 00:00:00 2001
From: Bruce Mitchener <bruce.mitchener@gmail.com>
Date: Fri, 8 Jan 2021 11:50:15 +0700
Subject: [PATCH] ptsname() needs _GNU_SOURCE on glibc. (#192)

glibc needs `_XOPEN_SOURCE` to have a declaration for
`ptsname()`. An easy way to get that without having to
know about particular `_XOPEN_SOURCE` values is to define
`_GNU_SOURCE`.

Closes interlisp/medley#137.
---
 src/unixcomm.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/unixcomm.c b/src/unixcomm.c
index ea02471..ead7fdf 100644
--- a/src/unixcomm.c
+++ b/src/unixcomm.c
@@ -9,6 +9,10 @@ Unix Interface Communications
 /* Don't compile this at all under DOS. */
 #ifndef DOS
 
+#ifndef _GNU_SOURCE
+#define _GNU_SOURCE /* Needed for ptsname on glibc systems. */
+#endif
+
 /************************************************************************/
 /*									*/
 /*	(C) Copyright 1989-1995 by Venue. All Rights Reserved.		*/