Hello All:
I found an issue about g++, it is OK for "-Wall -O0", but will report
-Wunused-variable for "-Wall -O1|2|3|s". The original version (e.g.
gcc 4.8.3 redhat version) does not report warning for "-Wall -O?".
The related operation:
[root@localhost qemu_cc]# cat test.cc
const char n() { return 1; }
const char c = n();
[root@localhost qemu_cc]# /usr/local/bin/g++ -Wall -O0 -c -o test.o test.cc
[root@localhost qemu_cc]# /usr/local/bin/g++ -Wall -O2 -c -o test.o test.cc
test.cc:2:12: warning: 'c' defined but not used [-Wunused-variable]
const char c = n();
^
The g++ information:
[root@localhost qemu_cc]# /usr/local/bin/g++ -v
Using built-in specs.
COLLECT_GCC=/usr/local/bin/g++
COLLECT_LTO_WRAPPER=/usr/local/libexec/gcc/x86_64-unknown-linux-gnu/5.0.0/lto-wrapper
Target: x86_64-unknown-linux-gnu
Configured with: ../gcc/configure --disable-multilibs --disable-nls
Thread model: posix
gcc version 5.0.0 20141003 (experimental) (GCC)
If we are sure it is a bug, I shall try to analyze it within this month.
Thanks
--
Chen Gang
Open, share, and attitude like air, water, and life which God blessed
