Dummy implementation of the roff(7) \V (interpolate environment variable)

escape sequence.  This is needed to get \V into the correct parsing
class, ESCAPE_EXPAND.

It is intentional that mandoc(1) output is *not* influenced by environment
variables, so interpolate the name of the variable with some decorating
punctuation rather than interpolating its value.

4 files changed, 32 insertions, 3 deletions

diff --git a/regress/roff/esc/Makefile b/regress/roff/esc/Makefile
index bd39e378..dd816f58 100644
--- a/regress/roff/esc/Makefile
+++ b/regress/roff/esc/Makefile
@@ -1,10 +1,10 @@
-# $OpenBSD: Makefile,v 1.21 2022/05/20 13:06:27 schwarze Exp $
+# $OpenBSD: Makefile,v 1.22 2022/05/30 22:50:40 schwarze Exp $
 
 REGRESS_TARGETS	 = one two multi comment
-REGRESS_TARGETS	+= B bs_man bs_mdoc c c_man E1 e f h hneg l O1 o p r w z
+REGRESS_TARGETS	+= B bs_man bs_mdoc c c_man E1 e f h hneg l O1 o p r V1 w z
 REGRESS_TARGETS	+= ignore invalid unsupp
 HTML_TARGETS	 = f
-LINT_TARGETS	 = comment B h l O1 r w ignore invalid unsupp
+LINT_TARGETS	 = comment B h l O1 r V1 w ignore invalid unsupp
 
 # mandoc defects:
 # - \h with a negative argument replaces output characters
@@ -13,4 +13,9 @@ LINT_TARGETS	 = comment B h l O1 r w ignore invalid unsupp
 
 SKIP_GROFF	 = hneg r
 
+# intentional difference:
+# - mandoc does not inspect the environment
+
+SKIP_GROFF	+= V1
+
 .include <bsd.regress.mk>
diff --git a/regress/roff/esc/V1.in b/regress/roff/esc/V1.in
new file mode 100644
index 00000000..3f1d76f7
--- /dev/null
+++ b/regress/roff/esc/V1.in
@@ -0,0 +1,10 @@
+.\" $OpenBSD: V1.in,v 1.1 2022/05/30 22:50:40 schwarze Exp $
+.TH ESC-V1 1 "May 31, 2022"
+.SH NAME
+esc-V1 \- interpolate environment variables
+.SH DESCRIPTION
+single-character name: "\VN"
+.br
+double-character name: "\V(VN"
+.br
+multi-character name: "\V[VARNAME]"
diff --git a/regress/roff/esc/V1.out_ascii b/regress/roff/esc/V1.out_ascii
new file mode 100644
index 00000000..2f22e58e
--- /dev/null
+++ b/regress/roff/esc/V1.out_ascii
@@ -0,0 +1,11 @@
+ESC-V1(1)                   General Commands Manual                  ESC-V1(1)
+
+NNAAMMEE
+       esc-V1 - interpolate environment variables
+
+DDEESSCCRRIIPPTTIIOONN
+       single-character name: "${N}"
+       double-character name: "${VN}"
+       multi-character name: "${VARNAME}"
+
+OpenBSD                          May 31, 2022                        ESC-V1(1)
diff --git a/regress/roff/esc/V1.out_lint b/regress/roff/esc/V1.out_lint
new file mode 100644
index 00000000..f580e4d2
--- /dev/null
+++ b/regress/roff/esc/V1.out_lint
@@ -0,0 +1,3 @@
+mandoc: V1.in:6:25: UNSUPP: unsupported feature: \VN
+mandoc: V1.in:8:25: UNSUPP: unsupported feature: \V(VN
+mandoc: V1.in:10:24: UNSUPP: unsupported feature: \V[VARNAME]