The mandoc(1) manual already mentions that -T man output mode

neither supports tbl(7) nor eqn(7) input.
If an input file contains such code anyway, tell the user
rather than failing an assert(3)ion.

Fixing a crash reported by Bjarni Ingi Gislason <bjarniig at rhi dot hi dot is>
in https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=901636 which the
Debian maintainer of mandoc, Michael at Stapelberg dot ch, forwarded to me.

5 files changed, 53 insertions, 12 deletions

diff --git a/TODO b/TODO
index 8e1f9652..51118130 100644
--- a/TODO
+++ b/TODO
@@ -228,6 +228,10 @@ are mere guesses, and some may be wrong.
 
 --- missing tbl features -----------------------------------------------
 
+- fully support the "nospaces" option;
+  Oliver Corff mentioned usefulness 20 Jun 2021 09:41:06 +0200
+  loc *  exist *  algo *  size *  imp *
+
 - vertical centering in cells vertically spanned with ^
   pali dot rohar at gmail dot com 16 Jul 2018 13:03:35 +0200
   loc *  exist ***  algo ***  size **  imp *
@@ -284,6 +288,7 @@ are mere guesses, and some may be wrong.
 
 - -T man does not handle eqn(7) and tbl(7)
   Stephen Gregoratto 16 Feb 2020 01:28:07 +1100
+  also https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=901636
   loc **  exist **  algo **  size ***  imp **
 
 - man -ks 1,8 route; kn@ Jul 13, 2018 orally
diff --git a/mandoc.1 b/mandoc.1
index a71518fb..00d898eb 100644
--- a/mandoc.1
+++ b/mandoc.1
@@ -2314,6 +2314,26 @@ or
 macro or of an undefined macro.
 The macro is ignored, and its arguments are handled
 as if they were a text line.
+.It Sy "skipping tbl in -Tman mode"
+.Pq mdoc , tbl
+An input file contains the
+.Ic \&TS
+macro.
+This message is only generated in
+.Fl T Cm man
+output mode, where
+.Xr tbl 7
+input is not supported.
+.It Sy "skipping eqn in -Tman mode"
+.Pq mdoc , eqn
+An input file contains the
+.Ic \&EQ
+macro.
+This message is only generated in
+.Fl T Cm man
+output mode, where
+.Xr eqn 7
+input is not supported.
 .El
 .Ss Bad command line arguments
 .Bl -ohang
diff --git a/mandoc.h b/mandoc.h
index 9d9fef8f..ba14c8fb 100644
--- a/mandoc.h
+++ b/mandoc.h
@@ -1,6 +1,6 @@
 /* $Id$ */
 /*
- * Copyright (c) 2012-2020 Ingo Schwarze <schwarze@openbsd.org>
+ * Copyright (c) 2012-2021 Ingo Schwarze <schwarze@openbsd.org>
  * Copyright (c) 2010, 2011, 2014 Kristaps Dzonsons <kristaps@bsd.lv>
  *
  * Permission to use, copy, modify, and distribute this software for any
@@ -245,6 +245,8 @@ enum	mandocerr {
 	MANDOCERR_TBLOPT_EQN, /* eqn delim option in tbl: arg */
 	MANDOCERR_TBLLAYOUT_MOD, /* unsupported tbl layout modifier: m */
 	MANDOCERR_TBLMACRO, /* ignoring macro in table: macro */
+	MANDOCERR_TBL_TMAN, /* skipping tbl in -Tman mode */
+	MANDOCERR_EQN_TMAN, /* skipping eqn in -Tman mode */
 
 	MANDOCERR_BADARG, /* ===== start of bad invocations ===== */
 
diff --git a/mandoc_msg.c b/mandoc_msg.c
index 64355ddc..8867bb4b 100644
--- a/mandoc_msg.c
+++ b/mandoc_msg.c
@@ -1,6 +1,6 @@
 /* $OpenBSD: mandoc_msg.c,v 1.8 2020/01/19 17:59:01 schwarze Exp $ */
 /*
- * Copyright (c) 2014-2020 Ingo Schwarze <schwarze@openbsd.org>
+ * Copyright (c) 2014-2021 Ingo Schwarze <schwarze@openbsd.org>
  * Copyright (c) 2010, 2011 Kristaps Dzonsons <kristaps@bsd.lv>
  *
  * Permission to use, copy, modify, and distribute this software for any
@@ -245,6 +245,8 @@ static	const char *const type_message[MANDOCERR_MAX] = {
 	"eqn delim option in tbl",
 	"unsupported tbl layout modifier",
 	"ignoring macro in table",
+	"skipping tbl in -Tman mode",
+	"skipping eqn in -Tman mode",
 
 	/* bad command line arguments */
 	NULL,
diff --git a/mdoc_man.c b/mdoc_man.c
index 7169b184..dcefc6e2 100644
--- a/mdoc_man.c
+++ b/mdoc_man.c
@@ -1,6 +1,6 @@
 /*	$Id$ */
 /*
- * Copyright (c) 2011-2020 Ingo Schwarze <schwarze@openbsd.org>
+ * Copyright (c) 2011-2021 Ingo Schwarze <schwarze@openbsd.org>
  *
  * Permission to use, copy, modify, and distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
@@ -660,7 +660,20 @@ print_node(DECL_ARGS)
 	do_sub = 1;
 	n->flags &= ~NODE_ENDED;
 
-	if (n->type == ROFFT_TEXT) {
+	switch (n->type) {
+	case ROFFT_EQN:
+	case ROFFT_TBL:
+		mandoc_msg(n->type == ROFFT_EQN ? MANDOCERR_EQN_TMAN :
+		    MANDOCERR_TBL_TMAN, n->line, n->pos, NULL);
+		outflags |= MMAN_PP | MMAN_sp | MMAN_nl;
+		print_word("The");
+		print_line(".B \\-T man", MMAN_nl);
+		print_word("output mode does not support");
+		print_word(n->type == ROFFT_EQN ? "eqn(7)" : "tbl(7)");
+		print_word("input.");
+		outflags |= MMAN_PP | MMAN_sp | MMAN_nl;
+		return;
+	case ROFFT_TEXT:
 		/*
 		 * Make sure that we don't happen to start with a
 		 * control character at the start of a line.
@@ -680,19 +693,18 @@ print_node(DECL_ARGS)
 			outflags &= ~(MMAN_spc | MMAN_spc_force);
 		else if (outflags & MMAN_Sm)
 			outflags |= MMAN_spc;
-	} else if (n->tok < ROFF_MAX) {
-		(*roff_man_acts[n->tok])(meta, n);
-		return;
-	} else {
-		/*
-		 * Conditionally run the pre-node action handler for a
-		 * node.
-		 */
+		break;
+	default:
+		if (n->tok < ROFF_MAX) {
+			(*roff_man_acts[n->tok])(meta, n);
+			return;
+		}
 		act = mdoc_man_act(n->tok);
 		cond = act->cond == NULL || (*act->cond)(meta, n);
 		if (cond && act->pre != NULL &&
 		    (n->end == ENDBODY_NOT || n->child != NULL))
 			do_sub = (*act->pre)(meta, n);
+		break;
 	}
 
 	/*