LI76793: NON VIRTUAL THUNK ERROR AT LINK TIME

XL C/C++ for Linux Fix Pack 9 (August 2013 Update) for 11.1
June 2012 Update for XL C/C++ for Linux, V11.1
October 2012 Update for XL C/C++ for Linux, V11.1
XL C/C++ for Linux Fix Pack 8 (June 2013 Update) for 11.1

APAR status

• Closed as program error.

Error description

• When compiling a test case that makes use of inline asm, you may
  get a link error related to non virtual thunks.
  
  Below is an example of the error message you may see:
  $ //Link step
  .
  .
  echo Linking...
  `_ZThn4_N7madness19DependencyInterfaceD1Ev' referenced in
  section `.rodata' of libMADworld.a(worldtask.o): defined in
  discarded section
  `.gnu.linkonce.t._ZThn4_N7madness19DependencyInterfaceD1Ev' of
  libMADworld.a(worldtask.o)
  `_ZThn4_N7madness19DependencyInterfaceD0Ev' referenced in
  section `.rodata' of libMADworld.a(worldtask.o): defined in
  discarded section
  `.gnu.linkonce.t._ZThn4_N7madness19DependencyInterfaceD0Ev' of
  libMADworld.a(worldtask.o)
  $
  
  If you do a c++filt on the above symbols, you get:
  $c++filt _ZThn4_N7madness19DependencyInterfaceD1Ev
  non-virtual thunk to
  madness::DependencyInterface::~DependencyInterface()
  $
  

Local fix

• n/a
  

Problem summary

• USERS AFFECTED:
  Users using assembly and C++ thunks may be affected by this
  issue.
  
  PROBLEM DESCRIPTION:
  GNU linker (ld) reports link errors when xlCcode generates c++
  thunk sections. The reason is c++ thunk sections are made as
  'linkonce' but will be referred locally from .rodata.
  In this condition, since there may be section discarded (from
  different object files), ld can not guarantee the reference is
  local.
  Therefore the error is reported.
  

Problem conclusion

• The compiler has been fixed to make the 'linkonce' symbols
  globally week, which eliminates this error.
  

Temporary fix

Comments

APAR Information

• APAR is sysrouted FROM one or more of the following:

  LI76610

• APAR is sysrouted TO one or more of the following:

Fix information

• Fixed component name

  XL C/C++ FOR LI

• Fixed component ID

  5724X1400

Applicable component levels

• RB10 PSN LI76610

     UP06/09/13