bug#30460: 27.0.50; `process-command' of a stopped process is t

bug#30460: 27.0.50; `process-command' of a stopped process is t

[p.stephani2]

(process-command
   (make-process :name "sleep" :command '("sleep" "1h") :stop t))

returns t.

This is not documented (the docstring and the manual say that this
should only happen for a pipe, network, or serial connection), and
breaks M-x list-processes, which assumes that the return value of
`process-command' is a list for an ordinary process.


In GNU Emacs 27.0.50 (build 13, x86_64-pc-linux-gnu, GTK+ Version 3.22.24)
  of 2018-02-14 built on localhost
Repository revision: 298275c595f6ca9e77f8131d34dda2b58fe1faa5
Windowing system distributor 'The X.Org Foundation', version 11.0.11903000
System Description: Debian GNU/Linux buster/sid

Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.

Configured using:
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  --enable-checking --enable-check-lisp-object-type --with-modules
  'CFLAGS=3D-O0 -ggdb3''

Configured features:
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ZLIB TOOLKIT_SCROLL_BARS GTK3 X11 MODULES JSON

Important settings:
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   locale-coding-system: utf-8-unix

Major mode: Lisp Interaction

Minor modes in effect:
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bug#30460: 27.0.50; `process-command' of a stopped process is t

[Eli Zaretskii]

> Date: Wed, 14 Feb 2018 23:00:26 +0100
> From: p.stephani2@gmail.com
> 
> 
> (process-command
>    (make-process :name "sleep" :command '("sleep" "1h") :stop t))
> 
> returns t.
> 
> This is not documented (the docstring and the manual say that this
> should only happen for a pipe, network, or serial connection), and
> breaks M-x list-processes, which assumes that the return value of
> `process-command' is a list for an ordinary process.

":stop t" currently has no effect on a "real" process running a
command, because it is not generally possible to start a process in a
stopped state.  So it's a Good Thing list-processes fails for such
bogus "processes" ;-)

We could fix this by either ignoring :stop in make-process, or by
signaling an error.  The simplest change is just delete this snipper
from Fmake_process:

  if (tem = Fplist_get (contact, QCstop), !NILP (tem))
    pset_command (XPROCESS (proc), Qt);

The correct command was already set by that time, so the above just
overwrites the correct expected value.

bug#30460: 27.0.50; `process-command' of a stopped process is t

[Philipp Stephani]

Am Sa., 17. Feb. 2018 um 14:25 Uhr schrieb Eli Zaretskii <eliz@gnu.org>:
>
> > Date: Wed, 14 Feb 2018 23:00:26 +0100
> > From: p.stephani2@gmail.com
> >
> >
> > (process-command
> >    (make-process :name "sleep" :command '("sleep" "1h") :stop t))
> >
> > returns t.
> >
> > This is not documented (the docstring and the manual say that this
> > should only happen for a pipe, network, or serial connection), and
> > breaks M-x list-processes, which assumes that the return value of
> > `process-command' is a list for an ordinary process.
>
> ":stop t" currently has no effect on a "real" process running a
> command, because it is not generally possible to start a process in a
> stopped state.  So it's a Good Thing list-processes fails for such
> bogus "processes" ;-)
>
> We could fix this by either ignoring :stop in make-process, or by
> signaling an error.

I prefer the second option for clarity and will send a patch in a moment.

bug#30460: [PATCH] Remove :stop key from make-process.

[Philipp Stephani]

This has never worked and caused issues such as Bug#30460.

* src/process.c (Fmake_process): Don't accept :stop key any more.
(syms_of_process): Define needed symbol 'null'.

* test/src/process-tests.el (make-process/stop): New unit test.

* doc/lispref/processes.texi (Asynchronous Processes): Remove :stop
key from manual.
---
 doc/lispref/processes.texi |  4 ----
 etc/NEWS                   |  3 +++
 src/process.c              | 13 ++++++-------
 test/src/process-tests.el  |  9 +++++++++
 4 files changed, 18 insertions(+), 11 deletions(-)

diff --git a/doc/lispref/processes.texi b/doc/lispref/processes.texi
index 6be311b563..e9f9d64cc3 100644
--- a/doc/lispref/processes.texi
+++ b/doc/lispref/processes.texi
@@ -677,10 +677,6 @@ Asynchronous Processes
 Initialize the process query flag to @var{query-flag}.
 @xref{Query Before Exit}.
 
-@item :stop @var{stopped}
-If @var{stopped} is non-@code{nil}, start the process in the
-stopped state.
-
 @item :filter @var{filter}
 Initialize the process filter to @var{filter}.  If not specified, a
 default filter will be provided, which can be overridden later.
diff --git a/etc/NEWS b/etc/NEWS
index 3e3454bd93..4d76143b13 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -1515,6 +1515,9 @@ The global value of 'indent-line-function', which defaults to
 To get back the old behavior, add a function to 'text-mode-hook' which
 performs (setq-local indent-line-function #'indent-relative).
 
+** 'make-process' no longer accepts a non-nil ':stop' key.  This has
+never worked reliably, and now causes an error.
+
 \f
 * Lisp Changes in Emacs 27.1
 
diff --git a/src/process.c b/src/process.c
index 0c44037162..412ced58de 100644
--- a/src/process.c
+++ b/src/process.c
@@ -1643,11 +1643,6 @@ ENCODING is used for writing.
 :noquery BOOL -- When exiting Emacs, query the user if BOOL is nil and
 the process is running.  If BOOL is not given, query before exiting.
 
-:stop BOOL -- Start process in the `stopped' state if BOOL non-nil.
-In the stopped state, a process does not accept incoming data, but you
-can send outgoing data.  The stopped state is cleared by
-`continue-process' and set by `stop-process'.
-
 :connection-type TYPE -- TYPE is control type of device used to
 communicate with subprocesses.  Values are `pipe' to use a pipe, `pty'
 to use a pty, or nil to use the default specified through
@@ -1746,8 +1741,10 @@ usage: (make-process &rest ARGS)  */)
 
   if (!query_on_exit)
     XPROCESS (proc)->kill_without_query = 1;
-  if (tem = Fplist_get (contact, QCstop), !NILP (tem))
-    pset_command (XPROCESS (proc), Qt);
+  tem = Fplist_get (contact, QCstop);
+  /* Normal processes can't be started in a stopped state, see
+     Bug#30460.  */
+  CHECK_TYPE (NILP (tem), Qnull, tem);
 
   tem = Fplist_get (contact, QCconnection_type);
   if (EQ (tem, Qpty))
@@ -8300,6 +8297,8 @@ returns non-`nil'.  */);
 	  "internal-default-interrupt-process");
   DEFSYM (Qinterrupt_process_functions, "interrupt-process-functions");
 
+  DEFSYM (Qnull, "null");
+
   defsubr (&Sprocessp);
   defsubr (&Sget_process);
   defsubr (&Sdelete_process);
diff --git a/test/src/process-tests.el b/test/src/process-tests.el
index 0bb7ebe50a..b853f77946 100644
--- a/test/src/process-tests.el
+++ b/test/src/process-tests.el
@@ -284,5 +284,14 @@ process-tests--file-handler
 (put #'process-tests--file-handler 'operations
      '(unhandled-file-name-directory make-process))
 
+(ert-deftest make-process/stop ()
+  "Check that `make-process' doesn't accept a `:stop' key.
+See Bug#30460."
+  (should-error
+   (make-process :name "test"
+                 :command (list (expand-file-name invocation-name
+                                                  invocation-directory))
+                 :stop t)))
+
 (provide 'process-tests)
 ;; process-tests.el ends here.
-- 
2.20.1 (Apple Git-117)

bug#30460: [PATCH] Remove :stop key from make-process.

[Eli Zaretskii]

> From: Philipp Stephani <p.stephani2@gmail.com>
> Cc: 30460@debbugs.gnu.org,
> 	Philipp Stephani <phst@google.com>
> Date: Fri, 19 Apr 2019 13:06:43 +0200
> 
> This has never worked and caused issues such as Bug#30460.
> 
> * src/process.c (Fmake_process): Don't accept :stop key any more.
> (syms_of_process): Define needed symbol 'null'.
> 
> * test/src/process-tests.el (make-process/stop): New unit test.
> 
> * doc/lispref/processes.texi (Asynchronous Processes): Remove :stop
> key from manual.

Please don't remove that, but instead document that it's an error to
use that keyword.

bug#30460: [PATCH] Remove :stop key from make-process.

[Philipp Stephani]

Am Fr., 19. Apr. 2019 um 13:27 Uhr schrieb Eli Zaretskii <eliz@gnu.org>:
>
> > From: Philipp Stephani <p.stephani2@gmail.com>
> > Cc: 30460@debbugs.gnu.org,
> >       Philipp Stephani <phst@google.com>
> > Date: Fri, 19 Apr 2019 13:06:43 +0200
> >
> > This has never worked and caused issues such as Bug#30460.
> >
> > * src/process.c (Fmake_process): Don't accept :stop key any more.
> > (syms_of_process): Define needed symbol 'null'.
> >
> > * test/src/process-tests.el (make-process/stop): New unit test.
> >
> > * doc/lispref/processes.texi (Asynchronous Processes): Remove :stop
> > key from manual.
>
> Please don't remove that, but instead document that it's an error to
> use that keyword.

OK, I've reworded it a bit and pushed as 5c5e309527.