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. 1.337, moving argument interpolation back into
the function roff_res().

1 files changed, 23 insertions, 0 deletions

diff --git a/regress/roff/return/basic.in b/regress/roff/return/basic.in
new file mode 100644
index 00000000..f0a777c1
--- /dev/null
+++ b/regress/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