http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50334
Bug #: 50334 Summary: interaction between -Wuninitialized and -finit-real=snan Classification: Unclassified Product: gcc Version: 4.6.1 Status: UNCONFIRMED Severity: normal Priority: P3 Component: fortran AssignedTo: unassig...@gcc.gnu.org ReportedBy: arnau...@users.sourceforge.net Considering subroutine qq(aa) aa = bb + 1 ! bb unset end subroutine >gfortran461 -O3 -Wuninitialized -c qq.f qq.f: In function 'qq': qq.f:2:0: warning: 'bb' is used uninitialized in this function [-Wuninitialized] >gfortran461 -O3 -Wuninitialized -finit-real=snan -c qq.f > The absence of compile-time warnings in the second case surprised me for a while until I tracked it down to "-finit-real=snan". "-finit-real=snan" is a killer feature of gfortran, badly missing in Intel Fortran for instance. It is somewhat regrettable that this option disables the compile-time warnings about uninitialized variables as "snan" in this case is used to find unset variables at run-time. Could you at least add a note in the description of "-finit-real=" explaining that "-finit-real=" will disable the warnings about uninitialized variables even for "snan"?