Support SIGTRAP in kill emulation on Windows

* src/w32proc.c (sys_kill): Translate SIGTRAP signal into a call to
'DebugBreakProcess' to cause a breakpoint exception to occur in the
specified process.  On Windows versions prior to Windows XP that do
not support 'DebugBreakProcess' return -1 and set errno to ENOTSUP
(as opposed to EINVAL before this change).
* src/w32proc.c: Add typedef for 'DebugBreakProcess' function pointer
and global variable to track state of run-time dynamic linking of this
function.

* etc/NEWS: Add entry to document that 'signal-process' now supports
SIGTRAP.

1 files changed, 10 insertions, 0 deletions

diff --git a/etc/NEWS b/etc/NEWS
index 59fb72a2bec..14450a6bbe5 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -668,6 +668,16 @@ session and exits.  In particular, this will happen if you start
 emacs.exe from the Windows shell, then type Ctrl-C into that shell's
 window.
 
+---
+** 'signal-process' supports SIGTRAP on Windows XP and later.
+The 'kill' emulation on Windows now maps SIGTRAP to a call to the
+'DebugBreakProcess' API.  This causes the receiving process to break
+execution and return control to the debugger.  If no debugger is
+attached to the receiving process, the call is typically ignored.
+This is in contrast to the default action on POSIX Systems, where it
+causes the receiving process to terminate with a core dump if no
+debugger has been attached to it.
+
 
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 This file is part of GNU Emacs.