[llvm-dev] LLVM deprecation policy

David Blaikie via llvm-dev llvm-dev at lists.llvm.org
Fri Aug 7 11:30:11 PDT 2020

On Fri, Aug 7, 2020 at 11:17 AM Paul C. Anagnostopoulos
<paul at windfall.com> wrote:
> Oh my. You think I should patch every .td file in the system?

Potentially, yes. If it's worth changing, important to figure out the
long-term migration strategy/technical debt of having two ways of
doing things, etc.

If this is a pure .td feature that doesn't change the resulting output
- you could validate the change (maybe updating one .td at a time) by
diffing the output of tblgen given old/new .td syntax & show that they
produce exactly the same output.

> That sounds a bit scary. I wrote a new test for range lists that tests the old and new range punctuator. And a release note is certainly in order. But I wasn't planning to patch all 600 .td files.

If it's not practical to automate (with sed, etc) and would be a very
long manual process (like 10s of hours) then - yeah, probably not
worth migrating everything up-front & just leave it as-is.

> At 8/7/2020 01:56 PM, David Blaikie wrote:
> >Fine by me to say the old thing's deprecated.
> >
> >Ideally, if it's not too painful - would be good if you could do a
> >complete migration to the new thing & remove the old thing, to help
> >keep things streamlined. (over multiple patches, with some
> >notification to llvm-dev and in release notes about the old thing
> >being deprecated and encouraging folks to move to the new thing ahead
> >of the removal of the old thing)
> >
> >On Fri, Aug 7, 2020 at 9:47 AM Paul C. Anagnostopoulos via llvm-dev
> ><llvm-dev at lists.llvm.org> wrote:
> >>
> >> I checked the Developer Policy and Coding Standards but couldn't find anything about deprecation. If I were to replace a simple bit of syntax in TableGen, what would I say in the documentation? Was the old syntax "deprecated"; or the new syntax "preferred"; or the old syntax simply not documented?

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