Re: [Mingw-users] MSYS_PREFIX_HACK

[Keith MARSHALL]

Earnie Boyd wrote:
> But if I change MSYS so that variable prefix is always a win32
> path value this MSYS_PREFIX_HACK would not need to be done ...

I'm curious as to how you might achieve that.

In a recently generated configure script I see the following
sequence of operations, invoked by AC_INIT:

1) Variable `ac_default_prefix' is explicitly initialised,
   as `ac_default_prefix=/usr/local'

2) Variable `prefix' is explicitly initialised, as
   `prefix=NONE'

3) Command line arguments are parsed; if `--prefix=value'
   is specified, then variable `prefix' is redefined, as
   `prefix=value'

Then, when we get to the AC_OUTPUT phase, I see:

  `test "x$prefix" = xNONE && prefix=$ac_default_prefix'

I know your objective with MSYS is to provide a minimal environment
for running `./configure && make', but some of us also use it simply
to have a usable shell on Win32 -- I know I am not not alone in saying
that cmd.exe and command.com are quite useless.  If you kludge MSYS, or
MSYS-bash, such that any attempt to define a variable called `prefix',
(or indeed, any other specifically named variable, other than those
which are documented as special in standard bash), then you diminish
its value as a generally useful UNIXy shell for Win32.  Expand that,
to treat other variable names as special cases, and you increase the
probability of nasty surprises even further, making MSYS even less
generally useful.

Surely, the better approach is to adapt autoconf, such that either
the AC_INIT setting of `ac_default_prefix' is more intelligent wrt
Win32 (or more specifically, MSYS) paths, or to adapt the AC_OUTPUT
reassignment of `prefix=$ac_default_prefix' to incorporate some
variant of the MSYS_PREFIX_HACK logic I presented earlier -- my
preference would be to have a more intelligent initialisation
for `ac_default_prefix', e.g. instead of:

  ac_default_prefix=/usr/local

say:

  ac_default_prefix=`exec 2>/dev/null;cd /usr/local;pwd -W` ||\
    ac_default_prefix=/usr/local

I have tested this alternative initialisation on every system
available to me.  On SunOS 5.5.1 with `sh', `ksh' and `bash', on
Linux 2.4.18 with `sh' which is linked to `bash', and on Cygwin
with `sh' and with `bash', it sets `ac_default_prefix=/usr/local',
while on my MSYS setup it sets `ac_default_prefix=d:/msys/1.0/local',
which is exactly the behaviour I want to see; (it does, of course,
require that the directory `d:/msys/1.0/local' already exists, when
the `pwd -W` is invoked, otherwise it would simply revert to the
`ac_default_prefix=/usr/local' behaviour).

Such autoconf modification *could* be restricted to the mingw.org
distribution of autotools, but then a regeneration of `configure'
would become a prerequisite phase of the MSYS build process, for
autoconf maintained packages.  A better solution, IMO, would be to
incorporate this as an autoconf standard.

BTW, I have opened a thread for this topic on address@hidden'.
This message is copied to both MinGW-users and to autoconf lists.

Best regards,
Keith.