D25494: Make tar archives reproducible by setting Pax headers

aaronpuchert created this revision.
aaronpuchert added a reviewer: kfunk.
Herald added a project: KDevelop.
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REVISION SUMMARY
  When POSIXLY_CORRECT is set, GNU tar will add ctime, atime and the PID
  of the tar process that created the archive, as pointed out in [1].
  To circumvent this, we set the Pax headers manually as recommended, but
  we only do this when SOURCE_DATE_EPOCH is set, i.e. reproducible builds
  are desired.
  
  [1] https://salsa.debian.org/reproducible-builds/reproducible-website/merge_requests/50/diffs

TEST PLAN
  Repeated builds produce the same files now. Changing the input files'
  timestamps seems without effect.

REPOSITORY
  R32 KDevelop

BRANCH
  pax-headers-reproducible

REVISION DETAIL
  https://phabricator.kde.org/D25494

AFFECTED FILES
  kdevplatform/cmake/modules/KDevPlatformMacros.cmake

To: aaronpuchert, kfunk
Cc: kdevelop-devel, hmitonneau, christiant, glebaccon, domson, antismap, iodelay, alexeymin, geetamc, Pilzschaf, akshaydeo, surgenight, arrowd