On 22 July 2013 17:22, Patrick Begou wrote: > Ian Lance Taylor wrote: >> >> >> Using optimization changes how your library header files behave. Look >> for #ifdef __OPTIMIZE__ or defined(__OPTIMIZE__). This looks like a >> problem with your C library, not with GCC proper. >> >> Ian >> > In http://gfortran.com/download/x86_64/PLEASE_README.txt the requirement for > glibc is : > "... The provided compilers need glibc 2.4 or newer, however the library > libgomp needs glibc 2.6...." > > I am runing glibc-devel-2.11.3-12.59.1.x86_64 > so my glibc level seams correct no ? Yes, but Ian didn't say your glibc is too old. Try looking for __OPTIMIZE__ and figuring out why you get different declarations with optimization enabled.