[Bug 1623418] Re: gcc-as-needed.diff patch broke mpx support in GCC

[Brian Murray]

Hello Alexander, or anyone else affected,

Accepted gcc-5 into xenial-proposed. The package will build now and be
available at
https://launchpad.net/ubuntu/+source/gcc-5/5.4.0-6ubuntu1~16.04.5 in a
few hours, and then in the -proposed repository.

Please help us by testing this new package.  See
https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how
to enable and use -proposed.Your feedback will aid us getting this
update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug,
mentioning the version of the package you tested and change the tag from
verification-needed-xenial to verification-done-xenial. If it does not
fix the bug for you, please add a comment stating that, and change the
tag to verification-failed-xenial. In either case, details of your
testing will help us make a better decision.

Further information regarding the verification process can be found at
https://wiki.ubuntu.com/QATeam/PerformingSRUVerification .  Thank you in
advance!

** Changed in: gcc-5 (Ubuntu Xenial)
       Status: New => Fix Committed

** Tags removed: verification-done-xenial
** Tags added: verification-needed verification-needed-xenial

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https://bugs.launchpad.net/bugs/1623418

Title:
  gcc-as-needed.diff patch broke mpx support in GCC

Status in gcc:
  Unknown
Status in binutils package in Ubuntu:
  Fix Released
Status in gcc-5 package in Ubuntu:
  Fix Released
Status in gcc-6 package in Ubuntu:
  Fix Released
Status in binutils source package in Xenial:
  Fix Released
Status in gcc-5 source package in Xenial:
  Fix Committed
Status in binutils source package in Yakkety:
  Won't Fix
Status in gcc-5 source package in Yakkety:
  Won't Fix
Status in gcc-6 source package in Yakkety:
  Won't Fix

Bug description:
  [SRU Justification]
  gcc-5 from Ubuntu is configured with MPX support, but it is broken due
  to always-added linker option "-as-needed".

  [Test case]
  1. Pass -mmpx to gcc when building an arbitrary project on x86.
  2. Verify with ldd that the resulting executable is not linked against libmpx.so because the -as-needed flag has discarded the mpx library from being linked in.
  3. Install binutils and gcc-5 from -proposed.
  4. Rebuild the target, again with -mmpx.
  5. Verify with ldd that the new executable is linked against libmpx.so.
  6. Verify that there are no regressions in the binutils testsuite on any architectures, by manually checking the results in the build log.

  [Regression potential]
  This binutils patch implements new --push-state / --pop-state options which will not be used in the common case, only when -mmpx is passed.  When these flags are not in use, which is the default, it should have no effect on the behavior of the toolchain, so risk of regression is minimal.


  Here is the GCC upstream bug & fix

  https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77267

  https://gcc.gnu.org/viewcvs/gcc?view=revision&revision=240057

  Would it be possible to backport this fix to Ubuntu gcc-5 build?

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