building Emacs on Msys2/mingw32

[Stephen Leake]

I've succesfully built Emacs on Msys2/mingw32. After I got some msys2
install issues sorted out, it went quite smoothly; almost as well as a
typical install on a Linxu/gnu box!

Thanks to all who made this possible!


I have suggested changes to the Msys2 people to iron out the Msys2
install issues I had.


To address the "almost" above:

I built from the current pretest tarball,
http://alpha.gnu.org/gnu/emacs/pretest/emacs-24.3.93.tar.xz

I had to override the guessed build machine on the configure line:

    $ ./configure --build=i686-pc-mingw32 --prefix=/mingw32

config.guess returns x86_64-pc-msys; configure rejects this.

x86_64-pc-msys is the correct host identifier, but we will never
actually build an Emacs for that machine; we will always want to build
for i686-pc-mingw32 or x86_64-pc-mingw32.

It might make sense to have configure translate x86_64-pc-msys to
x86_64-pc-mingw32, and i686-pc-msys to i686-pc-mingw32.

I'm not clear what MSYS (as opposed to MSYS2) does about this.

At least, this case should now be mentioned in nt/INSTALL. Here's a
suggested patch:

--- INSTALL     2014-09-08 10:42:54.523175900 -0500
+++ INSTALL.orig        2014-06-04 23:33:18.000000000 -0500
@@ -14,10 +14,10 @@
 
 * For the brave (a.k.a. "impatient"):
 
-  For those who have a working MSYS/MSYS2/MinGW development
-  environment and are comfortable with running Posix configure
-  scripts, here are the concise instructions for configuring and
-  building the native Windows binary of Emacs with these tools:
+  For those who have a working MSYS/MinGW development environment and
+  are comfortable with running Posix configure scripts, here are the
+  concise instructions for configuring and building the native Windows
+  binary of Emacs with these tools:
 
   0. Start the MSYS Bash window.  Everything else below is done from
      that window's Bash prompt.
@@ -41,14 +41,6 @@
 
         ./configure --prefix=PREFIX ...
 
-      - If you are building with MSYS2, you must specify the build machine:
-
-        --build=i686-pc-mingw32
-
-        or
-
-        --build=x86_64-pc-mingw32
-        
      It is always preferable to use --prefix to configure Emacs for
      some specific location of its installed tree; the default
      /usr/local is not suitable for Windows (see the detailed

@@ -83,16 +75,6 @@
   If these short instructions somehow fail, read the rest of this
   file.
 
-* Installing MinGW32 and MSYS2
-
-  Follow the instructions at 
http://sourceforge.net/p/msys2/wiki/MSYS2%20installation/
-
-  Install the compiler, and tar:
-
-  $ pacman -S mingw-w64-i686-toolchain tar
-
-  Follow the instructions above to build emacs.
-  
 * Installing MinGW and MSYS
 
   Make sure you carefully read the following two sections in their

-- 
-- Stephe