Re: MinGW build on master broken by Gnulib update

[Paul Eggert <eggert@cs.ucla.edu>]

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On 2024-09-04 22:43, Eli Zaretskii wrote:

> Gnulib moved the prototypes of sig2str and str2sig from sig2str.h to
> Gnulib's signal.h, evidently assuming that a build which uses the
> Gnulib sig2str will also use the Gnulib signal.h header, but that
> assumption is false for the MinGW build of Emacs, which omits
> lib/signal.h (because it clashes with some w32 code in Emacs).
> 
> I fixed that temporarily by modifying lib/sig2str.h to include the
> missing stuff for MinGW, but this is really a Gnulib issue, and should
> be fixed in Gnulib, IMO.

The change to Gnulib was to align with POSIX.1-2024, which declares 
sig2str and str2sig in <signal.h>; see:

https://pubs.opengroup.org/onlinepubs/9799919799/functions/sig2str.html

We don't want sig2str callers to depart from the POSIX API, any more 
than we'd want to require (say) fdopen callers to include a 
Gnulib-specific fdopen.h rather than including <stdio.h>.

Instead, how about adjusting Emacs's MinGW shims to supply the missing 
declarations? Something like the attached patch, say. (I don't use MinGW 
so can't easily test this.)

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From 0c17a34cdfbab86b4b44ea2b123f6d072e00ab79 Mon Sep 17 00:00:00 2001
From: Paul Eggert <eggert@cs.ucla.edu>
Date: Thu, 5 Sep 2024 09:22:41 -0700
Subject: [PATCH] Move MinGW sig2str workaround into ms-w32.h

* lib/sig2str.h: Go back to syncing exactly with Gnulib.
* nt/inc/ms-w32.h (SIG2STR_MAX): New macro.
(sig2str, str2sig): New decls.
---
 lib/sig2str.h   | 20 --------------------
 nt/inc/ms-w32.h |  7 +++++++
 2 files changed, 7 insertions(+), 20 deletions(-)

diff --git a/lib/sig2str.h b/lib/sig2str.h
index 62b6d628f12..1abdb140e5a 100644
--- a/lib/sig2str.h
+++ b/lib/sig2str.h
@@ -17,28 +17,8 @@
 
 /* Written by Paul Eggert.  */
 
-/* This file uses HAVE_* macros.  */
-# if !_GL_CONFIG_H_INCLUDED
-#  error "Please include config.h first."
-# endif
-
 #include <signal.h>
 
-/* Maximum size of a signal name returned by sig2str(), including the
-   terminating NUL byte.  */
-#ifndef SIG2STR_MAX
-/* The longest one: "RTMAX", then "+" or "-", then up to 10 digits, then NUL.
-   Add + 2 as a reserve for the future.  */
-# define SIG2STR_MAX (5 + 1 + 10 + 1 + 2)
-#endif
-
-#ifdef __MINGW32__
-int sig2str (int, char *);
-#endif
-#ifdef __MINGW32__
-int str2sig (char const *, int *);
-#endif
-
 /* An upper bound on signal numbers allowed by the system.  */
 
 #if defined _sys_nsig
diff --git a/nt/inc/ms-w32.h b/nt/inc/ms-w32.h
index 7212e4d2984..55273cbce79 100644
--- a/nt/inc/ms-w32.h
+++ b/nt/inc/ms-w32.h
@@ -427,6 +427,13 @@ #define SIG_BLOCK       1
 #define SIG_SETMASK     2
 #define SIG_UNBLOCK     3
 
+/* Maximum size of a signal name returned by sig2str(), including the
+   terminating NUL byte.  The longest one: "RTMAX", then "+" or "-",
+   then up to 10 digits, then NUL.  Add + 2 as a reserve for the future.  */
+#define SIG2STR_MAX (5 + 1 + 10 + 1 + 2)
+
+extern int sig2str (int, char *);
+extern int str2sig (char const *, int *);
 extern int sigemptyset (sigset_t *);
 extern int sigaddset (sigset_t *, int);
 extern int sigfillset (sigset_t *);
-- 
2.43.0