Implement appending to standard man(7) and mdoc(7) macros with .am.

With roff_getstrn(), provide finer control which definitions
can be used for what:
* All definitions can be used for .if d tests and .am appending.
* User-defined for \* expansion, .dei expansion, and macro calling.
* Predefined for \* expansion.
* Standard macros, original or renamed, for macro calling.

Several related improvements while here:
* Do not return string table entries that have explicitly been removed.
* Do not create a rentab entry when trying to rename a non-existent macro.
* Clear an existing rentab entry when the external interface
roff_setstr() is called with its name.
* Avoid trailing blanks in macro lines generated from renamed
and from aliased macros.
* Delete the duplicate __m*_reserved[] tables, just use roff_name[].

12 files changed, 100 insertions, 6 deletions

diff --git a/regress/roff/Makefile b/regress/roff/Makefile
index dae2ac37..61501033 100644
--- a/regress/roff/Makefile
+++ b/regress/roff/Makefile
@@ -1,7 +1,7 @@
 # $OpenBSD: Makefile,v 1.20 2015/02/06 16:05:51 schwarze Exp $
 
 SUBDIR  = args cond esc scale string
-SUBDIR += br cc de ds ft ig it ll na nr po ps rm sp ta ti tr
+SUBDIR += br cc de ds ft ig it ll na nr po ps rm rn sp ta ti tr
 
 .include "../Makefile.sub"
 .include <bsd.subdir.mk>
diff --git a/regress/roff/cond/string.in b/regress/roff/cond/string.in
index 6d19f4ce..4f27a492 100644
--- a/regress/roff/cond/string.in
+++ b/regress/roff/cond/string.in
@@ -27,3 +27,7 @@ mymacval
 .ie d myren now defined
 .el OOPS
 .if !d myren OOPS
+.PP
+standard macro is
+.ie d PP defined
+.el not defined \(em OOPS
diff --git a/regress/roff/cond/string.out_ascii b/regress/roff/cond/string.out_ascii
index 8df491ac..b5075d21 100644
--- a/regress/roff/cond/string.out_ascii
+++ b/regress/roff/cond/string.out_ascii
@@ -15,6 +15,8 @@ DDEESSCCRRIIPPTTIIOONN
        myren not yet defined
        now defined
 
+       standard macro is defined
+
 
 
 OpenBSD                          June 14, 2017                       STRING(1)
diff --git a/regress/roff/de/append.in b/regress/roff/de/append.in
index cdc01bdd..9e76f6d0 100644
--- a/regress/roff/de/append.in
+++ b/regress/roff/de/append.in
@@ -1,4 +1,4 @@
-.Dd July 7, 2014
+.Dd June 18, 2017
 .Dt DE-APPEND 1
 .Os OpenBSD
 .Sh NAME
@@ -23,3 +23,14 @@ ami:
 .mye
 .mym
 end
+.Pp
+standard macro:
+.Bo in brackets
+.Bc end
+.Pp
+append to standard macro:
+.am Bc
+.Pq appended words
+..
+.Bo in brackets
+.Bc end
diff --git a/regress/roff/de/append.out_ascii b/regress/roff/de/append.out_ascii
index c5f4363c..6230f3b2 100644
--- a/regress/roff/de/append.out_ascii
+++ b/regress/roff/de/append.out_ascii
@@ -6,4 +6,8 @@ NNAAMMEE
 DDEESSCCRRIIPPTTIIOONN
      de: OpenBSD am: OpenBSD NetBSD ami: OpenBSD NetBSD FreeBSD end
 
-OpenBSD                          July 7, 2014                          OpenBSD
+     standard macro: [in brackets] end
+
+     append to standard macro: [in brackets] end (appended words)
+
+OpenBSD                          June 18, 2017                         OpenBSD
diff --git a/regress/roff/rn/Makefile b/regress/roff/rn/Makefile
new file mode 100644
index 00000000..87ef7fe1
--- /dev/null
+++ b/regress/roff/rn/Makefile
@@ -0,0 +1,5 @@
+# $OpenBSD: Makefile,v 1.10 2017/03/07 20:00:02 schwarze Exp $
+
+REGRESS_TARGETS	 = append
+
+.include <bsd.regress.mk>
diff --git a/regress/roff/rn/append.in b/regress/roff/rn/append.in
new file mode 100644
index 00000000..5ae2cfb1
--- /dev/null
+++ b/regress/roff/rn/append.in
@@ -0,0 +1,23 @@
+.Dd June 18, 2017
+.Dt RN-APPEND 1
+.Os OpenBSD
+.Sh NAME
+.Nm rn-append
+.Nd append to renamed standard macro
+.Sh DESCRIPTION
+original macro:
+.Bo in brackets
+.Bc
+.Pp
+renamed macro:
+.rn Bc myBc
+.Bo in brackets
+.myBc
+.Pp
+appending to macro:
+.am myBc
+.Pq appended words
+..
+.Bo more in brackets
+.myBc
+final text
diff --git a/regress/roff/rn/append.out_ascii b/regress/roff/rn/append.out_ascii
new file mode 100644
index 00000000..99b61d79
--- /dev/null
+++ b/regress/roff/rn/append.out_ascii
@@ -0,0 +1,13 @@
+RN-APPEND(1)                General Commands Manual               RN-APPEND(1)
+
+NNAAMMEE
+     rrnn--aappppeenndd - append to renamed standard macro
+
+DDEESSCCRRIIPPTTIIOONN
+     original macro: [in brackets]
+
+     renamed macro: [in brackets]
+
+     appending to macro: [more in brackets] (appended words) final text
+
+OpenBSD                          June 18, 2017                         OpenBSD
diff --git a/regress/roff/string/Makefile b/regress/roff/string/Makefile
index d2cd125b..354a7a75 100644
--- a/regress/roff/string/Makefile
+++ b/regress/roff/string/Makefile
@@ -1,11 +1,15 @@
 # $OpenBSD: Makefile,v 1.6 2014/07/06 19:08:57 schwarze Exp $
 
-REGRESS_TARGETS=escape infinite zerolength name
-LINT_TARGETS = name
+REGRESS_TARGETS	 = escape infinite name std zerolength
+LINT_TARGETS	 = name std
 
 # The infinite test fails badly with groff-1.20.1:
 # It fails to print the following text.
 
-SKIP_GROFF ?= infinite
+SKIP_GROFF	?= infinite
+
+# Groff can expand standard macros as strings, but mandoc cannot.
+
+SKIP_GROFF	+= std
 
 .include <bsd.regress.mk>
diff --git a/regress/roff/string/std.in b/regress/roff/string/std.in
new file mode 100644
index 00000000..f460b101
--- /dev/null
+++ b/regress/roff/string/std.in
@@ -0,0 +1,10 @@
+.TH STRING-STD 1 "June 18, 2017" OpenBSD
+.SH NAME
+string-std - expanding standard macros as strings
+.SH DESCRIPTION
+expanding the DT macro as a string:
+>>>\*[DT]<<<
+.PP
+.rn DT myname
+the same after renaming it:
+>>>\*[myname]<<<
diff --git a/regress/roff/string/std.out_ascii b/regress/roff/string/std.out_ascii
new file mode 100644
index 00000000..b399374c
--- /dev/null
+++ b/regress/roff/string/std.out_ascii
@@ -0,0 +1,15 @@
+STRING-STD(1)               General Commands Manual              STRING-STD(1)
+
+
+
+NNAAMMEE
+       string-std - expanding standard macros as strings
+
+DDEESSCCRRIIPPTTIIOONN
+       expanding the DT macro as a string: >>><<<
+
+       the same after renaming it: >>><<<
+
+
+
+OpenBSD                          June 18, 2017                   STRING-STD(1)
diff --git a/regress/roff/string/std.out_lint b/regress/roff/string/std.out_lint
new file mode 100644
index 00000000..3f4dee30
--- /dev/null
+++ b/regress/roff/string/std.out_lint
@@ -0,0 +1,3 @@
+mandoc: std.in:6:4: WARNING: undefined string, using "": DT
+mandoc: std.in:10:4: WARNING: undefined string, using "": myname
+mandoc: std.in: STYLE: RCS id missing