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Re: problem with PATH set by libtool for uninstalled pixman library


On 29/07/2010 09:20, Charles Wilson wrote:
On 7/28/2010 2:24 PM, Jon TURNEY wrote:

I have a tinderbox which does daily builds of the X.Org stack for cygwin, and I've come across a something I don't understand with the way libtool is working when building the pixman library, and I hope someone can shed a bit of light.


(lt_update_lib_path) modifying 'PATH' by prepending
'/opt/jhbuild/build/pixman/pixman/.libs:'
(lt_setenv) setting 'PATH' to
'/opt/jhbuild/build/pixman/pixman/.libs:/home/jon/bin:/usr/local/bin:/usr/bin:/bin:/cygdrive/c/Windows/system32:/cygdrive/c/Windows:/cygdrive/c/Windows/System32/Wbem:/cygdrive/c/Windows/System32/WindowsPowerShell/v1.0/:/bin'

(lt_update_exe_path) modifying 'PATH' by prepending
'/opt/jhbuild/install/lib:/opt/jhbuild/install/bin:/opt/jhbuild/build/pixman/pixman/.libs:'

(lt_setenv) setting 'PATH' to
'/opt/jhbuild/install/lib:/opt/jhbuild/install/bin:/opt/jhbuild/build/pixman/pixman/.libs:/opt/jhbuild/build/pixman/pixman/.libs:/home/jon/bin:/usr/local/bin:/usr/bin:/bin:/cygdrive/c/Windows/system32:/cygdrive/c/Windows:/cygdrive/c/Windows/System32/Wbem:/cygdrive/c/Windows/System32/WindowsPowerShell/v1.0/:/bin'

This is because the wrapper prepends the rpath onto $$LIB_PATH_VARNAME, and prepends the dllsearchpath onto $$EXE_PATH_VARNAME.

But, since LIB_PATH_VARNAME==EXE_PATH_VARNAME on cygwin (both are
"PATH") that's basically saying:

PATH=$rpath:${PATH}
PATH=$dllsearchpath:${PATH}

I think it was a deliberate choice (e.g. on linux) for the wrapper to
add the $rpath to $LD_RUN_PATH, but...it's not such a great idea for win32.

This is a case where the wrapper exe was trying to do exactly what the
wrapper script used to do -- without considering whether the wrapper
script was doing the right thing, for this platform.

I think a patch to simply swap the order of these two assignments would
be fine (e.g. do $dllsearchpath first, then make sure it gets pre-empted
by $rpath). On *nix it wouldn't matter, since the two variables are
DISTINCT vars.

Okay, thanks very much for the explanation. This clarifies for me that this is a bug or platform quirk with libtool, and not something that pixman is doing wrong, so I can stick with the workaround I have for the moment.


I don't think I'm feeling brave enough at the moment to look at the libtool source:-)

As you can see, the install path appears before .libs in the PATH the
libtool wrapper constructs, so the installed version from a previous
build is used, rather than the uninstalled version we want to test.

I'm not quite clear why the install path is being added at all, I don't
think libpixman has any dependencies which it needs to find there (at
least in the cygwin build)

But libtool doesn't know that, at that particular point in the code.

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