http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58001
--- Comment #7 from Dominique d'Humieres <dominiq at lps dot ens.fr> --- > With -Wno-tabs, gfortran should report a warning for the > occurence of every tab used in the context of a character > from the Fortran character set. Taking your code, which I've > deleted here, and replace all whitespace by tabs, I get the > expected number of warnings. Historically, I wanted to use > -Wtabs as you expected, but there was too much wailing on > the gfortran lists, so it was changed to -Wno-tabs with the > meaning that "no tabs are allowed" in the context of the > Fortran character set. You'll notice that tabs within > a literal character string are not flagged. I cannot understand the rationale of this choice, but I guess it's too late to change it!-( > The history of -Wtabs verse -Wno-tabs can be found in the mailinglist > archive. No interest to dig the archives on this issue.