https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84885
--- Comment #6 from Steve Kargl <sgk at troutmask dot apl.washington.edu> --- On Fri, Mar 16, 2018 at 01:11:30PM +0000, mdblack98 at yahoo dot com wrote: > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84885 > > --- Comment #5 from mdblack98 at yahoo dot com --- > I've been using Fortran since 1980 so caps is natural to me :-) > My concern is that if gfortran has supported the len>1 convention for many > years than perhaps it should continue supporting it to prevent breaking code > like ours which will take some major effort to rewrite.Consider it an > "extension" to gfortran which apparently it was. Still fully 2018 compliant > with this one little extension. Enable it via a switch if you want to. First, gcc-bugzilla is probably not the appropriate forum for learning nuances of BIND(C). I suggest posting your questions to the comp.lang.fortran newsgroup or Stack Overflow. I've quoted two difference standards. Both state If the type is character, the length type parameter is interoperable if and only if its value is one. The above isn't a numbered constraint, so gfortran is not obligated to tell a user that in the following subroutine foo(c) use, intrinsic iso_c_binding character(len=1000, kind=c_char), bind(c) :: c end subroutine foo 'c' is not interoperable. Perhaps, gfortran should issue at least a warning. As long as a program does not try to use 'c' in an interoperable manner, gfortran appears to ignore the bind(c) attribute. If a program, however, uses 'c' in an interoperable manner, the user may get a result he expects even though it technically violates the Fortran standard. Now, when you wrap the character statement in a derived type subroutine foo(c) use, intrinsic :: iso_c_binding type, bind(c) :: bar character(len=1000, kind=c_char) :: c end type type(bar) bah bah%c = "123" end subroutine foo a numbered constraint comes into play. gfortran must tell the user that 'c' in type 'bar' is not interoperable. I quoted the relevant text already. From F2018 (and similar appears in other versions of the standard) C1806 (R726) Each component of a derived type with the BIND attribute shall be a nonpointer, nonallocatable data component with interoperable type and type parameters.
