Implement the roff \z escape sequence, intended to output the next

character without advancing the cursor position; implement it to
simply skip the next character, as it will usually be overwritten.

With this change, the pod2man(1) preamble user-defined string \*:,
intended to render as a diaeresis or umlaut diacritic above the
preceding character, is rendered in a slightly less ugly way,
though still not correctly.  It was rendered as "z.." and is now
rendered as ".".

Given that the definition of \*: uses elaborate manual \h positioning,
there is little chance for mandoc(1) to ever render it correctly,
but at least we can refrain from printing out a spurious "z", and
we can make the \z do something semi-reasonable for easier cases.

4 files changed, 54 insertions, 2 deletions

diff --git a/regress/usr.bin/mandoc/roff/Makefile b/regress/usr.bin/mandoc/roff/Makefile
index e4b892b517a..9bd19806a52 100644
--- a/regress/usr.bin/mandoc/roff/Makefile
+++ b/regress/usr.bin/mandoc/roff/Makefile
@@ -1,6 +1,6 @@
-# $OpenBSD: Makefile,v 1.8 2011/11/17 16:28:46 schwarze Exp $
+# $OpenBSD: Makefile,v 1.9 2012/05/28 13:00:51 schwarze Exp $
 
-SUBDIR+= args cond string br na ps rm sp
+SUBDIR+= args esc cond string br na ps rm sp
 
 ascii groff groff-clean obj-clean tman: _SUBDIRUSE
 
diff --git a/regress/usr.bin/mandoc/roff/esc/Makefile b/regress/usr.bin/mandoc/roff/esc/Makefile
new file mode 100644
index 00000000000..41c7afe8bc4
--- /dev/null
+++ b/regress/usr.bin/mandoc/roff/esc/Makefile
@@ -0,0 +1,15 @@
+# $OpenBSD: Makefile,v 1.1 2012/05/28 13:00:51 schwarze Exp $
+
+REGRESS_TARGETS=z
+
+# Postprocessing to remove "character backspace" sequences
+# unless they are foolowed by the same character again.
+# This removes underlining as well, so we mustn't use it.
+# Cannot use /g because matches progress backwards.
+
+z.out_ascii: z.in
+	${NROFF} ${.ALLSRC} | \
+		perl -pe 'while (s/(.)\010(?!\1)//) {}' \
+		> ${.TARGET}
+
+.include <bsd.regress.mk>
diff --git a/regress/usr.bin/mandoc/roff/esc/z.in b/regress/usr.bin/mandoc/roff/esc/z.in
new file mode 100644
index 00000000000..7076ebb0bcd
--- /dev/null
+++ b/regress/usr.bin/mandoc/roff/esc/z.in
@@ -0,0 +1,22 @@
+.Dd May 28, 2012
+.Dt ESC-Z 1
+.Os OpenBSD
+.Sh NAME
+.Nm esc-z
+.Nd the roff escape z sequence
+.Sh DESCRIPTION
+single z with ASCII char: >\zx<
+.br
+single z with escape char: >\z\(ci<
+.br
+.ds mystr mytext
+single z with defined string (\*[mystr]): >\z\*[mystr]<
+.br
+single z with font escape: >\z\fBxbold\fP<
+.br
+single z with nospace escape: >\z\c
+new line<
+.br
+single z with undefined escape: >\z\a<
+.br
+double z: >\z\zx<
diff --git a/regress/usr.bin/mandoc/roff/esc/z.out_ascii b/regress/usr.bin/mandoc/roff/esc/z.out_ascii
new file mode 100644
index 00000000000..aa1455b83f5
--- /dev/null
+++ b/regress/usr.bin/mandoc/roff/esc/z.out_ascii
@@ -0,0 +1,15 @@
+ESC-Z(1)                   OpenBSD Reference Manual                   ESC-Z(1)
+
+NNAAMMEE
+     eesscc--zz - the roff escape z sequence
+
+DDEESSCCRRIIPPTTIIOONN
+     single z with ASCII char: ><
+     single z with escape char: ><
+     single z with defined string (mytext): >ytext<
+     single z with font escape: >bboolldd<
+     single z with nospace escape: > new line<
+     single z with undefined escape: ><
+     double z: ><
+
+OpenBSD                          May 28, 2012                          OpenBSD