[Bug 906014] [NEW] Qt built with -Bsymbolic-functions, not using -reduce-relocations from configure

[Kevin Funk]

Public bug reported:

Qt is - at least in 11.04 and 12.04 - built with the -Bsymbolic-
functions linker flag enabled which binds references to global function
symbols to the definition within the shared library [1]. This is okay
for most use-cases out there but breaks certain scenarios where
preloading is involved.

Qt specifies certain dynamic-list files (see [2]) to enable dynamic
binding for certain symbols. An example file is
"QT_SOURCE/src/corelib/QtCore.dynlist". However, currently these files
are not used since Qt's configure is not instructed with -reduce-
relocations which would enable passing the --dynamic-list linker flag on
compilation. Note that this is only relevant if built with -Bsymbolic-
functions. In fact, -reduce-relocations both enable -Bsymbolic-functions
and --dynamic-list parameters to be passed.

Qt in 11.10 seems to be compiled without -Bsymbolic-function (checked
build logs on Launchpad).

[1] http://www.technovelty.org/code/c/bsymbolic-update.html
[2] http://linux.die.net/man/1/ld

** Affects: qt4-x11 (Ubuntu)
     Importance: Undecided
         Status: New

** Description changed:

  Qt is - at least in 11.04 and 12.04 - built with the -Bsymbolic-
  functions linker flag enabled which binds references to global function
  symbols to the definition within the shared library [1]. This is okay
  for most use-cases out there but breaks certain scenarios where
  preloading is involved.
  
  Qt specifies certain dynamic-list files (see [2]) to enable dynamic
  binding for certain symbols. An example file is
  "QT_SOURCE/src/corelib/QtCore.dynlist". However, currently these files
  are not used since Qt's configure is not instructed with -reduce-
  relocations which would enable passing the --dynamic-list linker flag on
- compilation. Not that this is only relevant if built with -Bsymbolic-
+ compilation. Note that this is only relevant if built with -Bsymbolic-
  functions. In fact, -reduce-relocations both enable -Bsymbolic-functions
  and --dynamic-list parameters to be passed.
  
  Qt in 11.10 seems to be compiled without -Bsymbolic-function (checked
  build logs on Launchpad).
  
  [1] http://www.technovelty.org/code/c/bsymbolic-update.html
  [2] http://linux.die.net/man/1/ld

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https://bugs.launchpad.net/bugs/906014

Title:
  Qt built with -Bsymbolic-functions, not using -reduce-relocations from
  configure

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