[Patch, Fortran, committed] PR36518 - Enable -Werror for libgfortran and fix a warning

[Tobias Burnus]

> The choice not to build libgfortran with -Werror is, I think,
> deliberate. Due to the large number of targets on which we have to
> build, we shouldn't do it, it will just be too much pain. (I haven't
> resources to do a bootstrap right now, but I'm for example almost sure
> that with the mingw headers, you'll get some warnings, e.g. about
> formats.)
Can you try to dig them up? Maybe we can fix some of those warnings.
(Does not need to be now, but I would like to see all warnings be
fixed. Too bad that the testresults@ do not contain such a list, I think
it would be helpful to fix some of the bugs.)

> We should probably change our
> requirements for patches so that patches to the library require
> maintainers to check that no new warnings are introduced (either by
> grepping the build logs, as I do, or by having an local modification
> adding -Werror if their target allows it.)
I agree with that.

I now removed the -Werror part of the patch (Rev. 136762).
(The casting patch is still in and should be not controversial.)

Tobias