Re: gcc parameter -mcrtdll= for choosing Windows C RunTime DLL library

[Eli Zaretskii <eliz@gnu.org>]

> Date: Sun, 20 Nov 2022 13:53:48 +0100
> From: Pali Rohár via Gcc <gcc@gcc.gnu.org>
> 
> Hello! I would like to propose a new parameter for gcc: -mcrtdll= to
> allow specifying against which Windows C Runtime library should be
> binary linked. On Windows there are more crt libraries and currently gcc
> links to libmsvcrt.a which is in most cases symlink to libmsvcrt-os.a
> (but can be changed, e.g. during mingw-w64 building). mingw-w64 project
> already builds import .a library for every crt dll library (from the old
> crtdll.dll up to the new ucrtbase.dll), so it is ready for usage. Simple
> patch for gcc which implements -mcrtdll parameter is below. Note that on
> internet are other very similar patches for -mcrtdll= parameters and
> some are parts of custom mingw32 / mingw-w64 gcc builds. What do you
> think? Could gcc have "official" support for -mcrtdll= parameter?

Linking a program against a specific runtime means the produced binary will
not run on Windows systems older than the one where it was linked.  Why is
such a limitation a good idea, may I ask?