Add recursive findfirst method for tuples.

[chriselrod]

https://discourse.julialang.org/t/why-does-findfirst-t-on-a-tuple-of-typed-only-constant-fold-for-the-first/68893

With this PR:

julia> position(::T) where T = findfirst(==(T), (Int, Float64, Char))
position (generic function with 1 method)

julia> @code_typed position(10)
CodeInfo(
1 ─     return 1
) => Int64

julia> @code_typed position(10.0)
CodeInfo(
1 ─     return 2
) => Int64

julia> @code_typed position('j')
CodeInfo(
1 ─     return 3
) => Int64

julia> @code_typed position(10f0)
CodeInfo(
1 ─     return nothing
) => Nothing

[KristofferC]

Note #42263

[aviatesk]

You can use e.g.:

@test Base.return_types() do
    findfirst(==(2), (1,2,3))
end == Any[Int]

as a test case that is supposed to be improved by this PR.

Also, how about adding findlast also ? It might be enough to add:

function findlast(f::Function, x::Tuple)
    r = findfirst(f, reverse(x))
    return isnothing(r) ? r : length(x) - r + 1
end

[aviatesk]

Let's use 4-spaces indents for Base:

Suggested change

	function findfirst(f::Function, x::Any32)
	for i in 1:length(x)
	f(x[i]) && return i
	end
	end
	function findfirst(f::Function, x::Any32)
	for i in 1:length(x)
	f(x[i]) && return i
	end
	end

[chriselrod]

Done, switched to 4 spaces and renamed to _findfirst_loop following #42263.
Also added the test case.

[aviatesk]

Let's see a benchmark result: @nanosoldier runbenchmarks(ALL, vs=":master")

[nanosoldier]

Something went wrong when running your job:

NanosoldierError: error when preparing/pushing to report repo: failed process: Process(setenv(`git push`; dir="/run/media/system/data/nanosoldier/workdir/NanosoldierReports"), ProcessExited(1)) [1]

Unfortunately, the logs could not be uploaded.
cc @christopher-dG

[aviatesk]

@vtjnash could you please upload the result ?

[vtjnash]

https://github.com/JuliaCI/NanosoldierReports/blob/master/benchmark/by_hash/2976c42_vs_7f26a7f/report.md

yep, looks unchanged to me

[aviatesk]

Thanks. And yeah, the result looks reasonable and I think this is good to go.

[KristofferC]

I guess this should be <= if we want to include the 32 case?

[chriselrod]

I went with < because Jeff did here: https://github.com/JuliaLang/julia/pull/42263/files

[aviatesk]

All CI failures are known issues.