https://github.com/n-t-roff/heirloom-doctools/commit/a5294cbbfd90e7b7b2c3c69186d6e67ba12bc913.patch
--- /dev/null Sat Jan 30 18:57:13 2021
+++ textproc/heirloom-doctools/patches/patch-troff_n5_c Sat Jan 30 18:55:00 2021
@@ -0,0 +1,17 @@
+$OpenBSD$
+
+Fix build with GCC 10.
+a5294cbbfd90e7b7b2c3c69186d6e67ba12bc913
+
+Index: troff/n5.c
+--- troff/n5.c.orig
++++ troff/n5.c
+@@ -1588,8 +1588,6 @@ caseie(void)
+ caseif(1);
+ }
+
+-int tryglf;
+-
+ void
+ caseif(int x)
+ {
