[PATCH] D64666: [Sema] Enable -Wimplicit-float-conversion for integral to floating point precision loss

Wed Jul 24 12:03:55 PDT 2019

aaron.ballman added a comment.

In D64666#1599544 <https://reviews.llvm.org/D64666#1599544>, @jfb wrote:

> In D64666#1599524 <https://reviews.llvm.org/D64666#1599524>, @ziangwan wrote:
>
> > In D64666#1598194 <https://reviews.llvm.org/D64666#1598194>, @jfb wrote:
> >
> > > Thanks, the update looks good.
> > >
> > > One thing I just noticed: if I have a codebase with `-Wimplicit-float-conversion` it seems like updating clang will automatically turn the two new warnings on, correct? That seems good, but also difficult to roll out because I can't turns off just the two new warnings. In other words, if I want to adopt a new clang and I had `-Wimplicit-float-conversion` then the only options I have are: fix all the new warnings (which might take time given how much code I have), or turn off *all* of `-Wimplicit-float-conversion`. I think it makes sense to force fixing all warnings for the warning that's always a problem `warn_impcast_integer_float_precision_constant`, but for `warn_impcast_integer_float_precision` it would be nice if there were a `-Wno-*` which disables only `warn_impcast_integer_float_precision` and nothing else.
> > >  This would make it way easier to roll out a new clang.
> >
> >
> > Yes, you are right. I am thinking about making a new flag for the warning but make "definitely lose" one default on. How about `-Wimplicit-int-float-conversion`?
>
>
> SGTM. It can still be a sub-warning of `-Wimplicit-float-conversion`, I just want to make sure we can turn it off on its own.

+1

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https://reviews.llvm.org/D64666