From 8ac38f574a96c57615e1047d033ad5b6d38d37f9 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?John=20Ankarstr=C3=B6m?= <john@ankarstrom.se>
Date: Thu, 17 Jun 2021 20:26:02 +0200
Subject: g.tmac: Fix environment stack underflow

---
 g.tmac | 41 ++++++++++++++++++++---------------------
 1 file changed, 20 insertions(+), 21 deletions(-)

diff --git a/g.tmac b/g.tmac
index f325daa..eb17536 100644
--- a/g.tmac
+++ b/g.tmac
@@ -1,30 +1,29 @@
 .eo
-.\" s -- setup document (configurable)
-.de s
-.sp 1i
-._d t \" title
-. ps +4p
-. vs +2p
-. ft B
-. ad c
-._d
-._d n \" name (of author)
-. ad c
-._d
-._d d \" date
-. ad c
-._d
-._d p \" paragraph
-. ad b
-._d
+.\" _s -- setup document (configurable)
+.de _s
+. sp 1i
+. _d t \" title
+.  ps +4p
+.  vs +2p
+.  ft B
+.  ad c
+. _d n \" name (of author)
+.  ad c
+. _d d \" date
+.  ad c
+. _d p \" paragraph
+.  ad b
+. _d
 ..
 .\" _d -- define environment
 .de _d
-. ev \$1
+. if !'\n[.ev]'0' .ev
+. if !'\$1'' .ev \$1
 ..
 .\" _e -- enter environment
 .de _e
-. ev
+.br
+. if !'\n[.ev]'0' .ev
 . ds penv \*[env]
 . ds env \$1
 . ev \$1
@@ -70,4 +69,4 @@
 \$3\f(BI\$1\fP\$2
 ..
 .ec
-.s
+._s
-- 
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