Launchpad invoking 64-bit programme in 32-bit build environment

[Colin Watson]

On Tue, Feb 09, 2016 at 09:34:24AM -0500, Luí­s de Sousa wrote:
> I am trying to package a Qt programme for Trusty. I have successfully built the package in my system and uploaded it to a PPA. The control file includes the following:
> 
> Build-Depends: debhelper (>= 8.0.0), cdbs, libpq-dev, libxml2-dev, clang, qt5-qmake, qt5-default, qttools5-dev-tools, qt5-image-formats-plugins
> 
> The Launchpad log file [0] appears to show that qt5-make is in fact installed in the build system. However, the compilation is issuing this error:
> 
> /usr/lib/x86_64-linux-gnu/qt5/bin/qmake -o Makefile pgmodeler.pro
> make[1]: /usr/lib/x86_64-linux-gnu/qt5/bin/qmake: Command not found
> make[1]: *** [Makefile] Error 127
> make[1]: Failed to remake makefile `Makefile'.
> 
> Why is the 64-bit version of qmake being invoked instead of the 32-bit?

Because that's what the Makefile in your package tells it to do:

  <cjwatson at niejwein ~/pgmodeler-0.8.2-beta (develop=)>$ grep -im2 x86.64 Makefile
  # Command: /usr/lib/x86_64-linux-gnu/qt5/bin/qmake -o Makefile pgmodeler.pro
  QMAKE         = /usr/lib/x86_64-linux-gnu/qt5/bin/qmake

Since that Makefile exists, the CDBS qmake handling that would normally
arrange to run qmake doesn't actually get run.

In this case, Makefile looks like a generated file.  I see that upstream
ships it, so you probably want to arrange to remove it at the start of
your build.  Something like this, since you're using CDBS:

  pre-build::
          rm -f Makefile

(Entirely untested, may need further tweaking, etc.)

There's nothing special about Launchpad here.  You should be able to
reproduce the same failure mode with sbuild
(https://wiki.ubuntu.com/SimpleSbuild), and I strongly recommend doing
so in order that you can iterate locally before uploading.

-- 
Colin Watson                                       [cjwatson at ubuntu.com]