[Bug 1237270] Re: linker: '-lpng' inhibits '-lz'

[Matthias Klose]

This is an error in how your local libfml.so is linked. make sure that
it is linked against libz.


** Changed in: gcc-defaults (Ubuntu)
       Status: New => Invalid

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Title:
  linker: '-lpng' inhibits '-lz'

Status in “gcc-defaults” package in Ubuntu:
  Invalid

Bug description:
  I got an error when building an executable from shared libraries, using GCC-4.7.3 provided by the linux distribution. I guess the problem is between libpng and zlib (the former uses the latter), but I don't know why. The following problem doesn't appear if I use a GCC version completely compiled by myself. Moreover, it doesn't occur on at least two other linux distros (Fedora 16 and ubuntu-10.04)
  ----------------------
  Description: when I issue the command:
  $ gfortran -o test_muesli_config_fml test_muesli_config_fml.o -fopenmp -Wl,--rpath,/usr/local/lib/muesli /usr/local/lib/muesli/libfml.so -lstdc++ -Wl,--rpath,/usr/lib /usr/lib/liblapack.so -Wl,--rpath,/usr/lib /usr/lib/libblas.so -lpng -lz -lpthread -lreadline -lhistory -Wl,--trace-symbol=gzwrite

  I obtained the error:
  /usr/local/lib/muesli/libfml.so: reference to gzwrite
  /usr/lib/gcc/x86_64-linux-gnu/4.7/../../../x86_64-linux-gnu/libz.so: definition of gzwrite
  /usr/local/lib/muesli/libfml.so: undefined reference to `gzwrite'
  /usr/local/lib/muesli/libfml.so: undefined reference to `gzopen'
  /usr/local/lib/muesli/libfml.so: undefined reference to `gzclose'
  /usr/local/lib/muesli/libfml.so: undefined reference to `gzread'
  collect2: error: ld returned 1 exit status

  If I remove the -lpng option (which is actually not used), the error
  disappear!

  In addition, a different try with another program (which USE libpng)
  leads to a successful build.

  ProblemType: Bug
  DistroRelease: Ubuntu 13.04
  Package: gcc 4:4.7.3-1ubuntu10
  ProcVersionSignature: Ubuntu 3.8.0-31.46-generic 3.8.13.8
  Uname: Linux 3.8.0-31-generic x86_64
  ApportVersion: 2.9.2-0ubuntu8.3
  Architecture: amd64
  Date: Wed Oct  9 10:11:16 2013
  InstallationDate: Installed on 2012-11-07 (335 days ago)
  InstallationMedia: Ubuntu 12.10 "Quantal Quetzal" - Release amd64 (20121017.5)
  MarkForUpload: True
  SourcePackage: gcc-defaults
  UpgradeStatus: Upgraded to raring on 2013-05-12 (149 days ago)

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