Introduce the concept of nodes that are semantically transparent:

they are skipped when looking for previous or following high-level
macros.  Examples include roff(7) .ft, .ll, and .ta, mdoc(7) .Sm
and .Tg, and man(7) .DT and .PD.  Use this concept for a variety
of improved decisions in various validators and formatters.

While here,
* remove a few const qualifiers on struct arguments that caused trouble;
* get rid of some more Yoda notation in the vicinity;
* and apply some other stylistic improvements in the vicinity.

I found this class of issues while considering .Tg patches from kn@.

23 files changed, 291 insertions, 14 deletions

diff --git a/regress/man/HP/Makefile b/regress/man/HP/Makefile
index 1e33cfb4..945f5339 100644
--- a/regress/man/HP/Makefile
+++ b/regress/man/HP/Makefile
@@ -1,6 +1,6 @@
-# $OpenBSD: Makefile,v 1.3 2019/01/06 04:41:15 schwarze Exp $
+# $OpenBSD: Makefile,v 1.4 2020/02/27 01:25:58 schwarze Exp $
 
-REGRESS_TARGETS = break literal macrotag manyargs spacing
+REGRESS_TARGETS = break literal macrotag manyargs spacing vert
 HTML_TARGETS	= literal
 
 .include <bsd.regress.mk>
diff --git a/regress/man/HP/vert.in b/regress/man/HP/vert.in
new file mode 100644
index 00000000..b433c7e0
--- /dev/null
+++ b/regress/man/HP/vert.in
@@ -0,0 +1,14 @@
+.\" $OpenBSD: vert.in,v 1.1 2020/02/27 01:25:58 schwarze Exp $
+.TH HP-VERT 1 "February 19, 2020"
+.SH NAME
+HP-vert \- vertical spacing before hanged lists
+.SH DESCRIPTION
+.PD 2v
+.HP
+Each hanged paragraph gets a sufficient amount of text
+to wrap to the next line.
+.HP
+Each hanged paragraph gets a sufficient amount of text
+to wrap to the next line.
+.LP
+Normal text.
diff --git a/regress/man/HP/vert.out_ascii b/regress/man/HP/vert.out_ascii
new file mode 100644
index 00000000..30fa3dd4
--- /dev/null
+++ b/regress/man/HP/vert.out_ascii
@@ -0,0 +1,21 @@
+HP-VERT(1)                  General Commands Manual                 HP-VERT(1)
+
+
+
+NNAAMMEE
+       HP-vert - vertical spacing before hanged lists
+
+DDEESSCCRRIIPPTTIIOONN
+       Each hanged paragraph gets a sufficient amount of text to wrap to the
+              next line.
+
+
+       Each hanged paragraph gets a sufficient amount of text to wrap to the
+              next line.
+
+
+       Normal text.
+
+
+
+OpenBSD                        February 19, 2020                    HP-VERT(1)
diff --git a/regress/man/IP/Makefile b/regress/man/IP/Makefile
index a677b970..70094e5f 100644
--- a/regress/man/IP/Makefile
+++ b/regress/man/IP/Makefile
@@ -1,7 +1,8 @@
-# $OpenBSD: Makefile,v 1.9 2019/01/06 04:41:15 schwarze Exp $
+# $OpenBSD: Makefile,v 1.10 2020/02/27 01:25:58 schwarze Exp $
 
-REGRESS_TARGETS = empty literal longhead manyargs spacing width
+REGRESS_TARGETS = bullet empty literal longhead manyargs spacing vert width
+UTF8_TARGETS	= bullet
 LINT_TARGETS	= empty
-HTML_TARGETS	= literal
+HTML_TARGETS	= bullet literal
 
 .include <bsd.regress.mk>
diff --git a/regress/man/IP/bullet.in b/regress/man/IP/bullet.in
new file mode 100644
index 00000000..138a681b
--- /dev/null
+++ b/regress/man/IP/bullet.in
@@ -0,0 +1,22 @@
+.\" $OpenBSD: bullet.in,v 1.1 2020/02/27 01:25:58 schwarze Exp $
+.TH IP-BULLET 1 "February 20, 2020"
+.SH NAME
+IP-bullet \- bullet lists
+.SH DESCRIPTION
+BEGINTEST
+.IP * 3n
+one
+.IP *
+two
+.IP \(bu
+three
+.IP \(bu
+four
+.IP \-
+five
+.IP \-
+six
+.PP
+ENDTEST
+.br
+end of file
diff --git a/regress/man/IP/bullet.out_ascii b/regress/man/IP/bullet.out_ascii
new file mode 100644
index 00000000..a01f25c2
--- /dev/null
+++ b/regress/man/IP/bullet.out_ascii
@@ -0,0 +1,28 @@
+IP-BULLET(1)                General Commands Manual               IP-BULLET(1)
+
+
+
+NNAAMMEE
+       IP-bullet - bullet lists
+
+DDEESSCCRRIIPPTTIIOONN
+       BEGINTEST
+
+       *  one
+
+       *  two
+
+       +o  three
+
+       +o  four
+
+       -  five
+
+       -  six
+
+       ENDTEST
+       end of file
+
+
+
+OpenBSD                        February 20, 2020                  IP-BULLET(1)
diff --git a/regress/man/IP/bullet.out_html b/regress/man/IP/bullet.out_html
new file mode 100644
index 00000000..95c452b0
--- /dev/null
+++ b/regress/man/IP/bullet.out_html
@@ -0,0 +1,12 @@
+<ul class="Bl-bullet">
+  <li>one</li>
+  <li>two</li>
+</ul>
+<ul class="Bl-bullet">
+  <li>three</li>
+  <li>four</li>
+</ul>
+<ul class="Bl-dash">
+  <li>five</li>
+  <li>six</li>
+</ul>
diff --git a/regress/man/IP/bullet.out_utf8 b/regress/man/IP/bullet.out_utf8
new file mode 100644
index 00000000..fa021fd5
--- /dev/null
+++ b/regress/man/IP/bullet.out_utf8
@@ -0,0 +1,28 @@
+IP-BULLET(1)                General Commands Manual               IP-BULLET(1)
+
+
+
+NNAAMMEE
+       IP-bullet - bullet lists
+
+DDEESSCCRRIIPPTTIIOONN
+       BEGINTEST
+
+       *  one
+
+       *  two
+
+       •  three
+
+       •  four
+
+       -  five
+
+       -  six
+
+       ENDTEST
+       end of file
+
+
+
+OpenBSD                        February 20, 2020                  IP-BULLET(1)
diff --git a/regress/man/IP/vert.in b/regress/man/IP/vert.in
new file mode 100644
index 00000000..cc5e2038
--- /dev/null
+++ b/regress/man/IP/vert.in
@@ -0,0 +1,10 @@
+.\" $OpenBSD: vert.in,v 1.1 2020/02/27 01:25:58 schwarze Exp $
+.TH IP-VERT 1 "February 19, 2020"
+.SH NAME
+IP-vert \- vertical spacing before indented paragraphs
+.SH DESCRIPTION
+.PD 2v
+.IP tag
+text
+.IP tag
+text
diff --git a/regress/man/IP/vert.out_ascii b/regress/man/IP/vert.out_ascii
new file mode 100644
index 00000000..428733be
--- /dev/null
+++ b/regress/man/IP/vert.out_ascii
@@ -0,0 +1,16 @@
+IP-VERT(1)                  General Commands Manual                 IP-VERT(1)
+
+
+
+NNAAMMEE
+       IP-vert - vertical spacing before indented paragraphs
+
+DDEESSCCRRIIPPTTIIOONN
+       tag    text
+
+
+       tag    text
+
+
+
+OpenBSD                        February 19, 2020                    IP-VERT(1)
diff --git a/regress/man/PP/Makefile b/regress/man/PP/Makefile
index 7655d294..a9eb9760 100644
--- a/regress/man/PP/Makefile
+++ b/regress/man/PP/Makefile
@@ -1,6 +1,6 @@
-# $OpenBSD: Makefile,v 1.4 2014/07/04 16:11:41 schwarze Exp $
+# $OpenBSD: Makefile,v 1.5 2020/02/27 01:25:58 schwarze Exp $
 
-REGRESS_TARGETS	= args empty
+REGRESS_TARGETS	= args empty vert
 LINT_TARGETS	= args empty
 
 .include <bsd.regress.mk>
diff --git a/regress/man/PP/vert.in b/regress/man/PP/vert.in
new file mode 100644
index 00000000..e15148c8
--- /dev/null
+++ b/regress/man/PP/vert.in
@@ -0,0 +1,10 @@
+.\" $OpenBSD: vert.in,v 1.1 2020/02/27 01:25:58 schwarze Exp $
+.TH PP-VERT 1 "February 19, 2020"
+.SH NAME
+PP-vert \- vertical spacing before an ordinary paragraph
+.SH DESCRIPTION
+.PD 2v
+.PP
+first paragraph
+.PP
+second paragraph
diff --git a/regress/man/PP/vert.out_ascii b/regress/man/PP/vert.out_ascii
new file mode 100644
index 00000000..ac53e071
--- /dev/null
+++ b/regress/man/PP/vert.out_ascii
@@ -0,0 +1,16 @@
+PP-VERT(1)                  General Commands Manual                 PP-VERT(1)
+
+
+
+NNAAMMEE
+       PP-vert - vertical spacing before an ordinary paragraph
+
+DDEESSCCRRIIPPTTIIOONN
+       first paragraph
+
+
+       second paragraph
+
+
+
+OpenBSD                        February 19, 2020                    PP-VERT(1)
diff --git a/regress/man/SH/Makefile b/regress/man/SH/Makefile
index 55133efe..f42a85b2 100644
--- a/regress/man/SH/Makefile
+++ b/regress/man/SH/Makefile
@@ -1,6 +1,6 @@
-# $OpenBSD: Makefile,v 1.6 2019/01/06 04:41:15 schwarze Exp $
+# $OpenBSD: Makefile,v 1.7 2020/02/27 01:25:58 schwarze Exp $
 
-REGRESS_TARGETS	= broken broken_eline empty_before longarg noarg paragraph
+REGRESS_TARGETS	= broken broken_eline empty_before longarg noarg paragraph vert
 LINT_TARGETS	= broken broken_eline empty_before noarg
 HTML_TARGETS	= paragraph
 
diff --git a/regress/man/SH/vert.in b/regress/man/SH/vert.in
new file mode 100644
index 00000000..e4154782
--- /dev/null
+++ b/regress/man/SH/vert.in
@@ -0,0 +1,10 @@
+.\" $OpenBSD: vert.in,v 1.1 2020/02/27 01:25:58 schwarze Exp $
+.TH SH-VERT 1 "February 20, 2020"
+.SH NAME
+SH-vert \- vertical spacing of sections
+.SH DESCRIPTION
+.PD 2v
+.SH EXAMPLES
+.PD 1v
+.PP
+text
diff --git a/regress/man/SH/vert.out_ascii b/regress/man/SH/vert.out_ascii
new file mode 100644
index 00000000..f8afd7e0
--- /dev/null
+++ b/regress/man/SH/vert.out_ascii
@@ -0,0 +1,14 @@
+SH-VERT(1)                  General Commands Manual                 SH-VERT(1)
+
+
+
+NNAAMMEE
+       SH-vert - vertical spacing of sections
+
+DDEESSCCRRIIPPTTIIOONN
+EEXXAAMMPPLLEESS
+       text
+
+
+
+OpenBSD                        February 20, 2020                    SH-VERT(1)
diff --git a/regress/man/SS/Makefile b/regress/man/SS/Makefile
index 0ae0fbc5..edbe4c2c 100644
--- a/regress/man/SS/Makefile
+++ b/regress/man/SS/Makefile
@@ -1,6 +1,6 @@
-# $OpenBSD: Makefile,v 1.4 2019/01/06 04:41:15 schwarze Exp $
+# $OpenBSD: Makefile,v 1.5 2020/02/27 01:25:58 schwarze Exp $
 
-REGRESS_TARGETS	= broken broken_eline longarg noarg paragraph
+REGRESS_TARGETS	= broken broken_eline longarg noarg paragraph vert
 LINT_TARGETS	= broken broken_eline noarg
 HTML_TARGETS	= paragraph
 
diff --git a/regress/man/SS/vert.in b/regress/man/SS/vert.in
new file mode 100644
index 00000000..8beb98a6
--- /dev/null
+++ b/regress/man/SS/vert.in
@@ -0,0 +1,12 @@
+.\" $OpenBSD: vert.in,v 1.1 2020/02/27 01:25:58 schwarze Exp $
+.TH SS-VERT 1 "February 19, 2020"
+.SH NAME
+SS-vert \- vertical spacing of subsections
+.SH DESCRIPTION
+.PD 2v
+.SS First subsection
+.PD 1v
+.SS Second subsection
+first paragraph
+.PP
+second paragraph
diff --git a/regress/man/SS/vert.out_ascii b/regress/man/SS/vert.out_ascii
new file mode 100644
index 00000000..9b5dc152
--- /dev/null
+++ b/regress/man/SS/vert.out_ascii
@@ -0,0 +1,17 @@
+SS-VERT(1)                  General Commands Manual                 SS-VERT(1)
+
+
+
+NNAAMMEE
+       SS-vert - vertical spacing of subsections
+
+DDEESSCCRRIIPPTTIIOONN
+   FFiirrsstt ssuubbsseeccttiioonn
+   SSeeccoonndd ssuubbsseeccttiioonn
+       first paragraph
+
+       second paragraph
+
+
+
+OpenBSD                        February 19, 2020                    SS-VERT(1)
diff --git a/regress/man/TP/Makefile b/regress/man/TP/Makefile
index 2fc1074f..ca2475b0 100644
--- a/regress/man/TP/Makefile
+++ b/regress/man/TP/Makefile
@@ -1,9 +1,9 @@
-# $OpenBSD: Makefile,v 1.15 2019/01/06 04:41:15 schwarze Exp $
+# $OpenBSD: Makefile,v 1.16 2020/02/27 01:25:58 schwarze Exp $
 
 REGRESS_TARGETS	 = badarg broken double eof fill indent literal longhead
-REGRESS_TARGETS	+= macrotag manyargs sameline spacing width
+REGRESS_TARGETS	+= macrotag manyargs sameline spacing vert width
 LINT_TARGETS	 = broken double eof
-HTML_TARGETS	 = literal
+HTML_TARGETS	 = literal vert
 
 # groff-1.22.3 defects:
 # - If .TP precedes .RE, the latter does not properly reset indentation.
diff --git a/regress/man/TP/vert.in b/regress/man/TP/vert.in
new file mode 100644
index 00000000..086976df
--- /dev/null
+++ b/regress/man/TP/vert.in
@@ -0,0 +1,17 @@
+.\" $OpenBSD: vert.in,v 1.1 2020/02/27 01:25:58 schwarze Exp $
+.TH TP-VERT 1 "February 19, 2020"
+.SH NAME
+TP-vert \- vertical spacing before tagged paragraphs
+BEGINTEST
+.SH DESCRIPTION
+.PD 2v
+.TP
+tag
+text
+.TP
+tag
+text
+.PP
+ENDTEST
+.br
+end of file
diff --git a/regress/man/TP/vert.out_ascii b/regress/man/TP/vert.out_ascii
new file mode 100644
index 00000000..32b26ca9
--- /dev/null
+++ b/regress/man/TP/vert.out_ascii
@@ -0,0 +1,20 @@
+TP-VERT(1)                  General Commands Manual                 TP-VERT(1)
+
+
+
+NNAAMMEE
+       TP-vert - vertical spacing before tagged paragraphs BEGINTEST
+
+DDEESSCCRRIIPPTTIIOONN
+       tag    text
+
+
+       tag    text
+
+
+       ENDTEST
+       end of file
+
+
+
+OpenBSD                        February 19, 2020                    TP-VERT(1)
diff --git a/regress/man/TP/vert.out_html b/regress/man/TP/vert.out_html
new file mode 100644
index 00000000..7301819f
--- /dev/null
+++ b/regress/man/TP/vert.out_html
@@ -0,0 +1,9 @@
+</section>
+<section class="Sh">
+<h1 class="Sh" id="DESCRIPTION"><a class="permalink" href="#DESCRIPTION">DESCRIPTION</a></h1>
+<dl class="Bl-tag">
+  <dt>tag</dt>
+  <dd>text</dd>
+  <dt>tag</dt>
+  <dd>text</dd>
+</dl>