bug#22959: Emacs on Windows depends on libwinpthreads

[Eli Zaretskii <eliz@gnu.org>]

> From: phillip.lord@russet.org.uk (Phillip Lord)
> Date: Wed, 09 Mar 2016 14:52:18 +0000
> 
> Currently, building Emacs under msys2/ming-w64 produces a binary that
> depends on libwinpthread.dll. The practical upshot of this is that after
> building and installing Emacs according to the instructions, Emacs
> cannot be launched from the Windows explorer -- it can be run from msys2
> which has the path set up correctly. A binary release will, therefore, fail.
> 
> Using the dependency walker shows the dependency is directly from Emacs,
> and it appears to have come from a change in ming-w64, as reported here.
> 
> https://sourceforge.net/p/mingw-w64/mailman/message/31213279/
> 
> https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=748353
> 
> This affects emacs-25, master and, indeed, emacs-24 built using the
> current tool chain.

If MinGW64 builds binaries that depend on libwinpthread DLL, then why
isn't that DLL part of the MinGW64 GCC installation?  That sounds like
a bug in MinGW64 packaging, or maybe your installation is somehow
incomplete or misconfigured?  (This is the first time that a MinGW64
Emacs user complains about this, so I wonder how others solve this
problem.)

The fact that Emacs runs OK when launched from MSYS2 Bash suggests
that the DLL exists, but is not on PATH.  Which might mean you need to
change your system configuration to augment PATH.

Or maybe you should use a different build of MinGW64 GCC?  The second
bug report you quote seems to indicate that there's a build which uses
Windows threads, so it doesn't depend on the pthread library.

Sorry, I don't use MinGW64, so I cannot help you more.