Implement the roff(7) .shift and .return requests,

for example used by groff_hdtbl(7) and groff_mom(7).

Also correctly interpolate arguments during nested macro execution
even after .shift and .return, implemented using a stack of argument
arrays.

Note that only read.c, but not roff.c can detect the end of a macro
execution, and the existence of .shift implies that arguments cannot
be interpolated up front, so unfortunately, this includes a partial
revert of roff.c rev. 1.209, moving argument interpolation back into
the function roff_res().

14 files changed, 185 insertions, 9 deletions

diff --git a/regress/usr.bin/mandoc/roff/Makefile b/regress/usr.bin/mandoc/roff/Makefile
index 7afa56d9b53..7c6f5e16dda 100644
--- a/regress/usr.bin/mandoc/roff/Makefile
+++ b/regress/usr.bin/mandoc/roff/Makefile
@@ -1,7 +1,7 @@
-# $OpenBSD: Makefile,v 1.24 2017/06/18 17:35:40 schwarze Exp $
+# $OpenBSD: Makefile,v 1.25 2018/08/23 14:16:12 schwarze Exp $
 
 SUBDIR  = args cond esc scale string
-SUBDIR += br cc de ds ft ig it ll na nr po ps rm rn sp ta ti tr
+SUBDIR += br cc de ds ft ig it ll na nr po ps return rm rn shift sp ta ti tr
 
 .include "../Makefile.sub"
 .include <bsd.subdir.mk>
diff --git a/regress/usr.bin/mandoc/roff/de/infinite.in b/regress/usr.bin/mandoc/roff/de/infinite.in
index 00931a06c18..dd17885f608 100644
--- a/regress/usr.bin/mandoc/roff/de/infinite.in
+++ b/regress/usr.bin/mandoc/roff/de/infinite.in
@@ -1,5 +1,5 @@
-.\" $OpenBSD: infinite.in,v 1.3 2017/07/04 14:53:27 schwarze Exp $
-.Dd $Mdocdate: July 4 2017 $
+.\" $OpenBSD: infinite.in,v 1.4 2018/08/23 14:16:12 schwarze Exp $
+.Dd $Mdocdate: August 23 2018 $
 .Dt DE-INFINITE 1
 .Os
 .Sh NAME
@@ -10,8 +10,8 @@ initial text
 .de mym
 .Op \\$1 \\$2
 ..
-.mym $1 \$1
-.mym \$1 nothing
+.mym $1 \$1 end
+.mym \$1 middle end
 middle text
 .de mym
 .mym
diff --git a/regress/usr.bin/mandoc/roff/de/infinite.out_ascii b/regress/usr.bin/mandoc/roff/de/infinite.out_ascii
index 452af775982..074362da409 100644
--- a/regress/usr.bin/mandoc/roff/de/infinite.out_ascii
+++ b/regress/usr.bin/mandoc/roff/de/infinite.out_ascii
@@ -4,6 +4,6 @@ NNAAMMEE
      ddee--iinnffiinniittee - inifinte recursion in a user-defined macro
 
 DDEESSCCRRIIPPTTIIOONN
-     initial text [$1 $1] middle text final text
+     initial text [$1 end] [middle end] middle text final text
 
-OpenBSD                          July 4, 2017                          OpenBSD
+OpenBSD                         August 23, 2018                        OpenBSD
diff --git a/regress/usr.bin/mandoc/roff/de/infinite.out_lint b/regress/usr.bin/mandoc/roff/de/infinite.out_lint
index e7beb090aa5..06254be506e 100644
--- a/regress/usr.bin/mandoc/roff/de/infinite.out_lint
+++ b/regress/usr.bin/mandoc/roff/de/infinite.out_lint
@@ -1,2 +1,3 @@
-mandoc: infinite.in:14:5: ERROR: input stack limit exceeded, infinite loop?
+mandoc: infinite.in:13:9: ERROR: using macro argument outside macro: \$1
+mandoc: infinite.in:14:6: ERROR: using macro argument outside macro: \$1
 mandoc: infinite.in:20:5: ERROR: input stack limit exceeded, infinite loop?
diff --git a/regress/usr.bin/mandoc/roff/return/Makefile b/regress/usr.bin/mandoc/roff/return/Makefile
new file mode 100644
index 00000000000..f7d510f7885
--- /dev/null
+++ b/regress/usr.bin/mandoc/roff/return/Makefile
@@ -0,0 +1,6 @@
+# $OpenBSD: Makefile,v 1.1 2018/08/23 14:16:12 schwarze Exp $
+
+REGRESS_TARGETS	= basic
+LINT_TARGETS	= basic
+
+.include <bsd.regress.mk>
diff --git a/regress/usr.bin/mandoc/roff/return/basic.in b/regress/usr.bin/mandoc/roff/return/basic.in
new file mode 100644
index 00000000000..f0a777c15f1
--- /dev/null
+++ b/regress/usr.bin/mandoc/roff/return/basic.in
@@ -0,0 +1,23 @@
+.\" $OpenBSD: basic.in,v 1.1 2018/08/23 14:16:12 schwarze Exp $
+.Dd $Mdocdate: August 23 2018 $
+.Dt RETURN-BASIC 1
+.Os
+.Sh NAME
+.Nm return-basic
+.Nd the return request
+.Sh DESCRIPTION
+return before macro
+.return
+.Pp
+.de mymacro
+text from macro (\\n(.$ argument: "\\$1"),
+.return
+not printed,
+..
+.mymacro myarg
+\n(.$ arguments after return: "\$1",
+.Pp
+return after macro
+.return
+.Pp
+final text
diff --git a/regress/usr.bin/mandoc/roff/return/basic.out_ascii b/regress/usr.bin/mandoc/roff/return/basic.out_ascii
new file mode 100644
index 00000000000..25f667442fc
--- /dev/null
+++ b/regress/usr.bin/mandoc/roff/return/basic.out_ascii
@@ -0,0 +1,15 @@
+RETURN-BASIC(1)             General Commands Manual            RETURN-BASIC(1)
+
+NNAAMMEE
+     rreettuurrnn--bbaassiicc - the return request
+
+DDEESSCCRRIIPPTTIIOONN
+     return before macro
+
+     text from macro (1 argument: "myarg"), 0 arguments after return: "",
+
+     return after macro
+
+     final text
+
+OpenBSD                         August 23, 2018                        OpenBSD
diff --git a/regress/usr.bin/mandoc/roff/return/basic.out_lint b/regress/usr.bin/mandoc/roff/return/basic.out_lint
new file mode 100644
index 00000000000..f4b15bac840
--- /dev/null
+++ b/regress/usr.bin/mandoc/roff/return/basic.out_lint
@@ -0,0 +1,3 @@
+mandoc: basic.in:10:2: ERROR: ignoring request outside macro: return
+mandoc: basic.in:18:32: ERROR: using macro argument outside macro: \$1
+mandoc: basic.in:21:2: ERROR: ignoring request outside macro: return
diff --git a/regress/usr.bin/mandoc/roff/shift/Makefile b/regress/usr.bin/mandoc/roff/shift/Makefile
new file mode 100644
index 00000000000..d356b963c85
--- /dev/null
+++ b/regress/usr.bin/mandoc/roff/shift/Makefile
@@ -0,0 +1,6 @@
+# $OpenBSD: Makefile,v 1.1 2018/08/23 14:16:12 schwarze Exp $
+
+REGRESS_TARGETS	= basic bad
+LINT_TARGETS	= bad
+
+.include <bsd.regress.mk>
diff --git a/regress/usr.bin/mandoc/roff/shift/bad.in b/regress/usr.bin/mandoc/roff/shift/bad.in
new file mode 100644
index 00000000000..809832defd8
--- /dev/null
+++ b/regress/usr.bin/mandoc/roff/shift/bad.in
@@ -0,0 +1,30 @@
+.\" $OpenBSD: bad.in,v 1.1 2018/08/23 14:16:12 schwarze Exp $
+.TH SHIFT_BAD 1 "August 23, 2018"
+.SH NAME
+.B shift-bad
+\(en wrong usage of macro arguments
+.SH DESCRIPTION
+initial text
+.de mym
+in macro: "\\$1"
+.PP
+invalid argument number 'x': "\\$x"
+..
+.PP
+argument used before call: "\$1"
+.shift
+.PP
+.mym argument
+.PP
+argument used after call: "\$1"
+.shift 2
+.PP
+.de mym
+.shift badarg
+after shift badarg: "\\$1"
+.shift 2
+after excessive shift: \\n(.$ "\\$1"
+..
+.mym arg1 arg2
+.PP
+final text
diff --git a/regress/usr.bin/mandoc/roff/shift/bad.out_ascii b/regress/usr.bin/mandoc/roff/shift/bad.out_ascii
new file mode 100644
index 00000000000..0b21f574a48
--- /dev/null
+++ b/regress/usr.bin/mandoc/roff/shift/bad.out_ascii
@@ -0,0 +1,25 @@
+SHIFT_BAD(1)                General Commands Manual               SHIFT_BAD(1)
+
+
+
+NNAAMMEE
+       sshhiifftt--bbaadd - wrong usage of macro arguments
+
+DDEESSCCRRIIPPTTIIOONN
+       initial text
+
+       argument used before call: ""
+
+       in macro: "argument"
+
+       invalid argument number 'x': ""
+
+       argument used after call: ""
+
+       after shift badarg: "arg2" after excessive shift: 0 ""
+
+       final text
+
+
+
+OpenBSD                         August 23, 2018                   SHIFT_BAD(1)
diff --git a/regress/usr.bin/mandoc/roff/shift/bad.out_lint b/regress/usr.bin/mandoc/roff/shift/bad.out_lint
new file mode 100644
index 00000000000..1f696fc8681
--- /dev/null
+++ b/regress/usr.bin/mandoc/roff/shift/bad.out_lint
@@ -0,0 +1,7 @@
+mandoc: bad.in:14:29: ERROR: using macro argument outside macro: \$1
+mandoc: bad.in:15:2: ERROR: ignoring request outside macro: shift
+mandoc: bad.in:17:31: ERROR: argument number is not numeric: \$x
+mandoc: bad.in:19:28: ERROR: using macro argument outside macro: \$1
+mandoc: bad.in:20:2: ERROR: ignoring request outside macro: shift
+mandoc: bad.in:28:8: ERROR: argument is not numeric, using 1: shift badarg
+mandoc: bad.in:28:9: ERROR: excessive shift: 2, but max is 1
diff --git a/regress/usr.bin/mandoc/roff/shift/basic.in b/regress/usr.bin/mandoc/roff/shift/basic.in
new file mode 100644
index 00000000000..982042db278
--- /dev/null
+++ b/regress/usr.bin/mandoc/roff/shift/basic.in
@@ -0,0 +1,35 @@
+.\" $OpenBSD: basic.in,v 1.1 2018/08/23 14:16:12 schwarze Exp $
+.TH SHIFT_BASIC 1 "August 23, 2018"
+.SH NAME
+.B shift-basic
+\(en the shift request
+.SH DESCRIPTION
+.de showargs
+original arguments:
+.BI \\$@
+.PP
+.shift 2
+after shift 2:
+.BI \\$@
+.PP
+.shift
+after shift without argument:
+.BI \\$@
+.PP
+.shift 0
+after shift 0:
+.BI \\$@
+..
+.de useargs
+<\\$*>
+..
+.showargs one two three four five
+.PP
+expand to less than three bytes:
+.useargs 1
+.PP
+expand to exactly three bytes:
+.useargs x y
+.PP
+expand to more than three bytes:
+.useargs "a longer argument..." "and another"
diff --git a/regress/usr.bin/mandoc/roff/shift/basic.out_ascii b/regress/usr.bin/mandoc/roff/shift/basic.out_ascii
new file mode 100644
index 00000000000..40675c67543
--- /dev/null
+++ b/regress/usr.bin/mandoc/roff/shift/basic.out_ascii
@@ -0,0 +1,25 @@
+SHIFT_BASIC(1)              General Commands Manual             SHIFT_BASIC(1)
+
+
+
+NNAAMMEE
+       sshhiifftt--bbaassiicc - the shift request
+
+DDEESSCCRRIIPPTTIIOONN
+       original arguments: oonnee_t_w_otthhrreeee_f_o_u_rffiivvee
+
+       after shift 2: tthhrreeee_f_o_u_rffiivvee
+
+       after shift without argument: ffoouurr_f_i_v_e
+
+       after shift 0: ffoouurr_f_i_v_e
+
+       expand to less than three bytes: <1>
+
+       expand to exactly three bytes: <x y>
+
+       expand to more than three bytes: <a longer argument... and another>
+
+
+
+OpenBSD                         August 23, 2018                 SHIFT_BASIC(1)