deprecate @pure and make it just alias to @assume_effects :foldable

[aviatesk]

This PR deprecates the @pure macro and removes all the internals that relate to the macro. It completes and replaces #48588.

[vtjnash]

Please try to preserve and add Co-authored-by tags

[aviatesk]

Whoops, I missed that I lost the tags during rebase. Thanks.

[aviatesk]

@nanosoldier runbenchmarks(!"scalar", vs=":master")

[nanosoldier]

Your benchmark job has completed - possible performance regressions were detected. A full report can be found here.

[aviatesk]

No regressions. This should be ready to go.

[KristofferC]

-1 for the hard deprecation here. It is an internal that changes to another internal. Just put it in deprecated.jl without a deprecation and be done with it. No need to spam gazillions of warnings to normal users.

[oscardssmith]

the counterpoint is that 90% of uses of @pure were broken anyway. We added the deprecation early enough in the release that I'm hoping the result is that all the advanced people who run on master go around and fix all of the broken uses of @pure

[KristofferC]

How is that a counter point? Whose life is better now when we get a bazillion warnings from precompile for any package install?

I'm hoping the result is that all the advanced people who run on master go around and fix all of the broken uses of @pure

No one is stopping anyone from doing that. Just don't spam my terminal with pages of warnings.

[maleadt]

This also broke Compat.jl 3.x, which quite a few packages still use.
https://github.com/JuliaLang/Compat.jl/blob/v3.46.0/src/Compat.jl#L282
IMO removals like this should have been preceded by a PkgEval run, and fixes to packages.

[martinholters]

Would that be solved by making the if in Compat a @static if? We could do that in a patch release of the v3 branch, I guess.

[maleadt]

Yeah, I think that should work.

[StefanKarpinski]

With the new definition, isn't it more likely that uses of @pure are now correct?

[oscardssmith]

They would be, but most uses of @pure were straight up broken. Eg @pure f() = error(). Almost all uses of @pure were pre 1.0 and are neither correct nor needed.

[aviatesk]

Base.@assume_effects :foldable f() = error() is valid :p I don't know much about @pure usages in the wild, but I guess they are not all correct even given the new definition.