https://gcc.gnu.org/bugzilla/show_bug.cgi?id=49278
--- Comment #26 from anlauf at gcc dot gnu.org --- (In reply to kargl from comment #23) > (In reply to anlauf from comment #21) > > There's also valid code that ICEs, and invalid code that is silently > > accepted. > > > > Invalid code: > > > > program p > > implicit none > > integer, parameter :: b = 1 > > data b / 2 / > > print *, b > > end > > > > Instead of being rejected, this prints: > > 1 > > You need know about gfortran's extensions. > > % gfcx -Wall -o z -std=f95 a.f90 > a.f90:4:12: > > 4 | data b / 2 / > | 1 > Error: GNU Extension: re-initialization of 'b' at (1) I hope you noticed the PARAMETER, which should have been caught by -fno-writable-parameters ... ;-)