Hi, * Alexei Sheplyakov <varg@theor.jinr.ru> [Jan 21. 2008 12:33]:
Hello!
On Sun, Jan 20, 2008 at 12:17:51PM +1100, Joerg Arndt wrote:
by default you use (1) only -O, I suggest to use -O2 (but not -O3).
I'm not sure if CLN code is safe to compile with plain -O2.
This would be a serios problem IMHO!
With CXXFLAGS="-m64 -O2 -Wall -march=k8 -finline-limit=2000" I get tons of warnings like
../../include/cln/number.h: In constructor 'cln::cl_number::cl_number(float)': ../../include/cln/number.h:238: warning: type-punning to incomplete type might break strict-aliasing rules ../../include/cln/number.h: In member function 'cln::cl_number& cln::cl_number::operator=(float)': ../../include/cln/number.h:238: warning: type-punning to incomplete type might break strict-aliasing rules ../../include/cln/number.h: In constructor 'cln::cl_number::cl_number(double)': ../../include/cln/number.h:239: warning: type-punning to incomplete type might break strict-aliasing rules
Then -no-strict-aliasing should be used! It seems to me that with strict aliasing and ignoring the warnings we just proceed "fingers crossed" (?)
Just for the record, I use g++-4.1 (GCC) 4.1.2 20061115 (prerelease) (Debian 4.1.1-21).
(2) no warnings!, I suggest to use -W -Wall -Wconversion -Wsign-promo -Wsign-compare -Wunused \ -Wshadow -Wundef
-Wall spews a lot of warnings, and signal/noise ratio is quite low for this to be useful.
I do that for my stuff all the time: I consider an warning as a problem and fix it. When I _know_ there is no problem then I use a (C-style) cast and comment it. I found quite a few subtle problems by doing this.
... and -Werror if you are daring
Unfortunately, CLN won't compile with -Werror.
Clearly so. I use -Werror and do a make -k ("keep going"), then I go through the file where the problems occur.
Best regards, Alexei
after all the above is done (a monumental task with CLN, obviously) valgrind pointed me to a few _very_ subtle problems which I'd never found by other other means! cheers, jj