I've updated libtool-devel to the 20030121 CVS, plus added a major
change of my own (inspired by Earnie Boyd and others on the libtool
mailing list) that "fixes" the 'relink exe's over and over and over'
problem on both mingw and cygwin.
[Skip to the last two paragraphs for the real important part]
A (not-so-short) description of the problem and the solution approach
taken: if you have a package that builds a shared library (.dll) AND an
exe which relies on that library, then libtool puts the actual
executable into a .lib/ subdirectory under your current build directory,
and NOT in the build directory itself.
This is also done on "real" unix platforms. The reason is that
uninstalled shared libraries cannot easily be found by the runtime
loader on most platforms, unix and cygwin/windows included.
So, in order to run the uninstalled executable, you must first set the
environment appropriately so that the shared library (.dll) will be
found. This means setting LD_LIBRARY_PATH on some unices, or setting
PATH on cygwin so that the Windows Runtime Loader will find the .dll.
libtool does this by creating a shell script in the actual build
directory. The shell script sets the variables and then exec's
./lib/my-real-executable.
If your application is "foo", this works fine on unix. The makefile
wants to see 'foo' -- and it does; only the 'foo' that make sees is
actually a shell script:
<builddir>/foo : a shell script
<builddir>/.lib/foo : the real executable
And it only gets built once. However, on cygwin/windows, you have
<builddir>/foo : a shell script
<builddir>/.lib/foo.exe : the real executable
and the makefile *wants* 'foo.exe' -- but only sees 'foo'. Therefore,
make assumes that the executable hasn't been created, and builds it
again. EVERY time you run 'make <anything>'. Sometimes *multiple*
times if there are cross-dependencies.
There were several solutions:
1) Teach 'make' to only want 'foo' instead of 'foo.exe'. There are
problems here -- this requires mucking with automake, which has the
potential to break non-libtool builds if not done carefully.
Do you have seen thatg ltmain.sh defines for cygwin the .exe extension ? Automake
creates rules like
<application>$(EXEEXT): ...
so setting this exeext to an empty string catch this.
case $host in
*cygwin*)
exeext=.exe
outputname=`echo $outputname|${SED} 's,.exe$,,'` ;;
*) exeext= ;;
esac
Ralf
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