Make PrecompileTools into a stdlib

[timholy]

This makes PrecompileTools an upgradable stdlib.
While it will still live in its own repository, this allows
it to be used by other stdlibs to lower their TTFX
when they migrate out.

[timholy]

After a slack discussion with @KristofferC, we concluded that because we'd also need to make Preferences an upgradable stdlib, it might be better to vendor the ~60LOC needed from PrecompileTools.

[vchuravy]

I think we only didn't make preferences as stdlib, because at the time we hadn't figured out how to make them upgradeable.

@staticfloat and I want to eventually use Preferences for behaviour in Base (but not include Preferences in the sysimg)

[timholy]

I'm happy to reopen this if we get to a point where we want it.

[vchuravy]

I now want this :)

[timholy]

Back from the dead! But we'll need Preferences before we can merge this, I think.

[KristofferC]

I now want this :)

Why?

But we'll need Preferences before we can merge this, I think.

:(

[vchuravy]

I originally thought I would need it for #51350, but I was mistaken.

I can see a use for this when we have a lot of upgradeable stdlibs that don't want to maintain explicit precompile statement lists.

(We could also vendor a Preference free version, but I don't feel to bad about making Preferences an upgradeable stdlib.)

[mkitti]

Could we move some code from PrecompileTools.jl into Base or Core?

In particular, the ccalls really should be wrapped into a Julia function.

ccall(:jl_generating_output, Cint, ())
ccall(:jl_debug_method_invalidation, Any, (Cint,), 1)

[IanButterworth]

Is there anything stopping us making Preferences.jl and PrecompileTools.jl upgradable stdlibs?

I ask because it would be nice to fix things like this without having every downstream stdlib re-craft workloads that trigger the recompilation.

 inserting print(io::IO, c::Base.AnnotatedChar) @ StyledStrings ~/Documents/GitHub/julia/usr/share/julia/stdlib/v1.12/StyledStrings/src/io.jl:281 invalidated:
   backedges: 1: superseding print(io::IO, c::AbstractChar) @ Base char.jl:261 with MethodInstance for print(::IOBuffer, ::Base.AnnotatedChar{Char}) (40 children)
              2: superseding print(io::IO, c::AbstractChar) @ Base char.jl:261 with MethodInstance for print(::IOContext{IOStream}, ::Base.AnnotatedChar{Char}) (82 children)
              3: superseding print(io::IO, c::AbstractChar) @ Base char.jl:261 with MethodInstance for print(::IOContext{IOBuffer}, ::Base.AnnotatedChar{Char}) (309 children)
   3 mt_cache

via the approach

module SomeStdlib

using PrecompileTools
@recompile_invalidations begin
    using StyledStrings and other stdlib deps...
end
...
end

[timholy]

@recompile_invalidations should be a last resort---it's intended more for end users who want to easily create effective personal Startup.jl packages than for routine use in packages. Has anyone diagnosed what's being invalidated? Perhaps many of those can be fixed?

[IanButterworth]

The issue seems fundamental with how StyledStrings is split between the stdlib and Base, hence the need to heal rather than fix. JuliaLang/StyledStrings.jl#61

[timholy]

Isn't just fixing the piracy the better solution?

[KristofferC]

Jeff doesn't want more cruft in Base. So somehow this "compromise" was made where only part of the AnnotatedString API was moved into Base and part of it (the thing that renders colors etc when an annotated string happens to have those annotations) was left in StyledString.

[IanButterworth]

REPL and Pkg now use the PrecompileTools mechanics
#55782
JuliaLang/Pkg.jl#4024

I'm not sure whether this should be closed, but that's a lot of the latency sensitive UX stuff improved.