invoke.texi: Document -Wunderflow and spell check.
* invoke.texi: Document -Wunderflow and spell check.
* lang.opt: Add Wunderflow.
* gfortran.h (gfc_option_t): Add warn_underflow option.
* options.c (gfc_init_options, set_Wall): Use it.
* primary.c (match_real_constant): Explicitly handle UNDERFLOW.
* arith.c (gfc_arith_uminus, gfc_arith_plus, gfc_arith_minus,
gfc_arith_times, gfc_arith_divide, gfc_arith_power, gfc_real2real,
gfc_real2complex, gfc_complex2real, gfc_complex2complex): Ditto.
* arith.c (common_logarithm): Fix typo in comment.
From-SVN: r82130