[Bug c++/40056] New: implicit instantiation of function templates fails with -O2, works with -O and -g...

[Bug c++/40056] New: implicit instantiation of function templates fails with -O2, works with -O and -g...

[Fons dot Rademakers at cern dot ch]

The attached file TStreamerInfoReadBuffer.cxx fails to instantiate template
functions when compiled with -O2. With -O or -g things work as expected. This
is a regression that does not appear in <4.4.0.

Compile the attached file with:

 g++ -O2 -m64 -c TStreamerInfoReadBuffer.cxx -o TStreamerInfoReadBuffer.o

do:

 nm TStreamerInfoReadBuffer.o | grep
__ZN13TStreamerInfo10ReadBufferIPPcEEiR7TBufferRKT_iiii

and no symbol will be found.

Compile with -O:

g++ -O -m64 -c TStreamerInfoReadBuffer.cxx -o TStreamerInfoReadBuffer.o

And:

nm TStreamerInfoReadBuffer.o | grep
__ZN13TStreamerInfo10ReadBufferIPPcEEiR7TBufferRKT_iiii
00000000000603f2 S __ZN13TStreamerInfo10ReadBufferIPPcEEiR7TBufferRKT_iiii
000000000006ba70 S __ZN13TStreamerInfo10ReadBufferIPPcEEiR7TBufferRKT_iiii.eh


-- 
           Summary: implicit instantiation of function templates fails with
                    -O2, works with -O and -g...
           Product: gcc
           Version: 4.4.0
            Status: UNCONFIRMED
          Severity: blocker
          Priority: P3
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: Fons dot Rademakers at cern dot ch
 GCC build triplet: i686-apple-darwin9
  GCC host triplet: i686-apple-darwin9
GCC target triplet: i686-apple-darwin9


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40056

[Bug c++/40056] implicit instantiation of function templates fails with -O2, works with -O and -g...

[Fons dot Rademakers at cern dot ch]

------- Comment #1 from Fons dot Rademakers at cern dot ch  2009-05-07 10:01 -------
Created an attachment (id=17817)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=17817&action=view)
Source file (-E output) demonstrating the reported issue.

Btw, this bug shows up on MacOS X 10.5.6, Linux RHEL 5 and Ubuntu 9, i.e. it is
platform independent.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40056

[Bug c++/40056] implicit instantiation of function templates fails with -O2, works with -O and -g...

[pinskia at gcc dot gnu dot org]

-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |pinskia at gcc dot gnu dot
                   |                            |org
           Severity|blocker                     |normal


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40056

[Bug c++/40056] implicit instantiation of function templates fails with -O2, works with -O and -g...

[pinskia at gcc dot gnu dot org]

------- Comment #2 from pinskia at gcc dot gnu dot org  2009-05-07 12:25 -------
The implicit instantiation of function templates could be inlined at which
point, it does not need to be emitted.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40056

[Bug c++/40056] implicit instantiation of function templates fails with -O2, works with -O and -g...

[Fons dot Rademakers at cern dot ch]

------- Comment #3 from Fons dot Rademakers at cern dot ch  2009-05-07 13:55 -------
Explicit template instantiation also works for us in this case. However, would
be nice to see this regression fixed. No blocker anymore.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40056