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@.

4 files changed, 37 insertions, 2 deletions

diff --git a/regress/mdoc/Sh/Makefile b/regress/mdoc/Sh/Makefile
index 1c20f13f..213664ec 100644
--- a/regress/mdoc/Sh/Makefile
+++ b/regress/mdoc/Sh/Makefile
@@ -1,7 +1,8 @@
-# $OpenBSD: Makefile,v 1.11 2019/01/07 06:51:37 schwarze Exp $
+# $OpenBSD: Makefile,v 1.12 2020/02/27 01:25:58 schwarze Exp $
 
 REGRESS_TARGETS	 = badNAME before empty emptyNAME first nohead order
-REGRESS_TARGETS	+= orderNAME paragraph parbefore parborder punctNAME subbefore
+REGRESS_TARGETS	+= orderNAME paragraph parbefore parborder punctNAME
+REGRESS_TARGETS	+= subbefore transp
 LINT_TARGETS	 = badNAME before empty emptyNAME first nohead order
 LINT_TARGETS	+= orderNAME parbefore parborder punctNAME subbefore
 HTML_TARGETS	 = paragraph
diff --git a/regress/mdoc/Sh/transp.in b/regress/mdoc/Sh/transp.in
new file mode 100644
index 00000000..ef24d380
--- /dev/null
+++ b/regress/mdoc/Sh/transp.in
@@ -0,0 +1,11 @@
+.\" $OpenBSD: transp.in,v 1.1 2020/02/27 01:25:58 schwarze Exp $
+.Dd $Mdocdate$
+.Dt SH-TRANSP 1
+.Os
+.Sh NAME
+.Nm Sh-transp
+.Nd interaction of sections with transparent nodes
+.Sh DESCRIPTION
+.Tg transparent
+.Ss Subsection
+text
diff --git a/regress/mdoc/Sh/transp.out_ascii b/regress/mdoc/Sh/transp.out_ascii
new file mode 100644
index 00000000..e30d327f
--- /dev/null
+++ b/regress/mdoc/Sh/transp.out_ascii
@@ -0,0 +1,10 @@
+SH-TRANSP(1)                General Commands Manual               SH-TRANSP(1)
+
+NNAAMMEE
+     SShh--ttrraannsspp - interaction of sections with transparent nodes
+
+DDEESSCCRRIIPPTTIIOONN
+   SSuubbsseeccttiioonn
+     text
+
+OpenBSD                        February 27, 2020                       OpenBSD
diff --git a/regress/mdoc/Sh/transp.out_markdown b/regress/mdoc/Sh/transp.out_markdown
new file mode 100644
index 00000000..f395ed50
--- /dev/null
+++ b/regress/mdoc/Sh/transp.out_markdown
@@ -0,0 +1,13 @@
+SH-TRANSP(1) - General Commands Manual
+
+# NAME
+
+**Sh-transp** - interaction of sections with transparent nodes
+
+# DESCRIPTION
+
+## Subsection
+
+text
+
+OpenBSD - February 27, 2020