On Thu, 18 Apr 2024, Nikita Kniazev wrote:
From 0d9fb95b2c50a15a90276f67e7ec44c67cb1093b Mon Sep 17 00:00:00 2001
From: Nikita Kniazev <kniazev.nik...@gmail.com>
Date: Thu, 18 Apr 2024 03:37:48 +0000
Subject: [PATCH] crt: execv*/spawnv* const-correctness
Signed-off-by: Nikita Kniazev <kniazev.nik...@gmail.com>
---
mingw-w64-headers/crt/process.h | 26 +++++++++++++-------------
1 file changed, 13 insertions(+), 13 deletions(-)
diff --git a/mingw-w64-headers/crt/process.h
b/mingw-w64-headers/crt/process.h
index 1ac39a064..8c35372a3 100644
--- a/mingw-w64-headers/crt/process.h
+++ b/mingw-w64-headers/crt/process.h
@@ -183,20 +183,20 @@ extern "C" {
stupid warnings, define them in POSIX way. This is save, because
those
methods do not return in success case, so that the return value is not
really dependent to its scalar width. */
- _CRTIMP int __cdecl execv(const char *_Filename,char *const _ArgList[])
__MINGW_ATTRIB_DEPRECATED_MSVC2005;
- _CRTIMP int __cdecl execve(const char *_Filename,char *const
_ArgList[],char *const _Env[]) __MINGW_ATTRIB_DEPRECATED_MSVC2005;
- _CRTIMP int __cdecl execvp(const char *_Filename,char *const _ArgList[])
__MINGW_ATTRIB_DEPRECATED_MSVC2005;
- _CRTIMP int __cdecl execvpe(const char *_Filename,char *const
_ArgList[],char *const _Env[]) __MINGW_ATTRIB_DEPRECATED_MSVC2005;
+ _CRTIMP int __cdecl execv(const char *_Filename,const char *const
_ArgList[]) __MINGW_ATTRIB_DEPRECATED_MSVC2005;
Thanks, I think this patch is correct, so I think we should apply it.
However, this is a quite subtle area, and this can actually cause breakage
in user code.
A "char**" pointer can't be implicitly converted to a "const char**"
pointer - see https://c-faq.com/ansi/constmismatch.html for the full
explanation for this issue.
That said, MSVC's header seem to have const applied on these pointers like
you suggest, already in ancient versions like MSVC 6, up to the latest
versions using UCRT. So therefore, the change certainly is motivated, and
reduces the amount of unnecessary differences to MSVC.
However, on the other side, the POSIX spec for the exec* family of
functions, declare them without const here:
https://pubs.opengroup.org/onlinepubs/9699919799/functions/exec.html
So we gain conformance with MSVC, but lose conformance with POSIX. (OTOH,
our functions are named with leading underscores, which can motivate them
differing.)
In any case, while correct, this change can (and probably will) definitely
break building some user code that has so far worked, depending on
language mode and warning strictness etc. (Code that is built with both
MSVC and mingw might not have such issues though as there already was a
divergence.)
// Martin
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