Remove :stop key from make-process.

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.

1 files changed, 3 insertions, 1 deletions

diff --git a/doc/lispref/processes.texi b/doc/lispref/processes.texi
index 6be311b5639..43009b35b2a 100644
--- a/doc/lispref/processes.texi
+++ b/doc/lispref/processes.texi
@@ -678,7 +678,9 @@ 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
+@var{stopped} must be @code{nil}.  The @code{:stop} key is ignored
+otherwise and is retained for compatibility with other process types
+such as pipe processes.  Asynchronous subprocesses never start in the
 stopped state.
 
 @item :filter @var{filter}