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

[bircoph at gmail dot com]

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

Andrew Savchenko <bircoph at gmail dot com> changed:

           What    |Removed                     |Added
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                 CC|                            |bircoph at gmail dot com

--- Comment #5 from Andrew Savchenko <bircoph at gmail dot com> 2012-03-08 
14:28:48 UTC ---
The problem is still here with gcc-4.5.3 if compiled with -O3:

x86_64-pc-linux-gnu-gcc -O -march=core2 -m64 -c TStreamerInfoReadBuffer.cxx -o
TStreamerInfoReadBuffer-1.o
x86_64-pc-linux-gnu-gcc -O2 -march=core2 -m64 -c TStreamerInfoReadBuffer.cxx -o
TStreamerInfoReadBuffer-2.o
x86_64-pc-linux-gnu-gcc -O3 -march=core2 -m64 -c TStreamerInfoReadBuffer.cxx -o
TStreamerInfoReadBuffer-1.o

nm TStreamerInfoReadBuffer-1.o | grep
_ZN13TStreamerInfo10ReadBufferIPPcEEiR7TBufferRKT_iiii
0000000000000000 W _ZN13TStreamerInfo10ReadBufferIPPcEEiR7TBufferRKT_iiii
nm TStreamerInfoReadBuffer-2.o | grep
_ZN13TStreamerInfo10ReadBufferIPPcEEiR7TBufferRKT_iiii
0000000000000000 W _ZN13TStreamerInfo10ReadBufferIPPcEEiR7TBufferRKT_iiii
nm TStreamerInfoReadBuffer-3.o | grep
_ZN13TStreamerInfo10ReadBufferIPPcEEiR7TBufferRKT_iiii
0000000000007b10 t
_ZN13TStreamerInfo10ReadBufferIPPcEEiR7TBufferRKT_iiii.clone.26

The guilty is -fipa-cp-clone option. Without it symbol is defined well:
x86_64-pc-linux-gnu-gcc -O3 -fno-ipa-cp-clone -march=core2 -m64 -c
TStreamerInfoReadBuffer.cxx -o TStreamerInfoReadBuffer-3-fipa-cp-clone.o
nm TStreamerInfoReadBuffer-3-fipa-cp-clone.o | grep
_ZN13TStreamerInfo10ReadBufferIPPcEEiR7TBufferRKT_iiii
0000000000000000 W _ZN13TStreamerInfo10ReadBufferIPPcEEiR7TBufferRKT_iiii