Implement new .soquiet and .msoquiet requests.

Needed for two planned developments: (1) the i18n patch in Savannah
bug #59814 can use this to quietly attempt to open a localization file.
groff only supports a few locales, so people with LANG=es_ES, for
instance, would ordinarily see warning diagnostics on every groff
startup if file warnings were enabled; and (2) system- or
site-configurable support of per-user {.,}troffrc or man.local files,
gracefully failing if they don't exist.

* src/roff/troff/input.cpp:
  (do_source): Add new function, taking boolean "quietly" parameter and
  absorbing function of source(), with added conditional.

  (source): Convert into a wrapper to call do_source() unquietly.

  (source_quietly): Wrap do_source(), quietly.

  (do_macro_source, macro_source, macro_source_quietly): Analogous to
  the foregoing.

  (init_requests): Hook "msoquiet" to macro_source_quietly() and
  "soquiet" to "source_quietly().

* doc/groff.texi (I/O):
* man/groff.7.man (Requests/Request short reference):
* man/groff_diff.7.man (Language/New requests): Document them.

* src/roff/groff/tests/msoquiet_works.sh:
* src/roff/groff/tests/soquiet_works.sh: Test them.

* src/roff/groff/groff.am (groff_TESTS): Add tests.

Fixes <https://savannah.gnu.org/bugs/?59973>.

1 files changed, 4 insertions, 0 deletions

diff --git a/NEWS b/NEWS
index 22c4d8851..4a726cfd1 100644
--- a/NEWS
+++ b/NEWS
@@ -54,6 +54,10 @@ o Point-size escapes of the form '\sNN', where NN is in the range 10-39,
   advanced usage) are expected to be able to cope; ask the development
   team for support if you need it.
 
+o New requests 'soquiet' and 'msoquiet' are available.  They operate as
+  'so' and 'mso', respectively, except that they do not emit a warning
+  diagnostic if the file name argument does not exist.
+
 o New requests 'stringdown' and 'stringup' are available.  These change
   the string named in their argument by replacing each of its bytes with
   its lowercase or uppercase version (if any), respectively.  groff