specialize VersionNumber constructors less aggressively

[topolarity]

There's no need to specialize this code for every set of Tuple types that it might see, especially when the primary callers don't know their Tuple type any more precisely than this anyway.

Eliminates a dynamic dispatch from tryparse(VersionNumber, "...")

[topolarity]

On second thought, this is probably not the right change...

We'd really like to specialize on the Vararg parameters here, but not on the length of the tuple.

[topolarity]

For now I'm going to back out of this part of these changes, until we have a solution for: #54390

Thankfully, the other call-site should be fine to de-specialize since it's a small, concrete union.

[aviatesk]

If it proves ineffective to generate code based on the tuple lengths for this case, should we probably refactor the whole code to use Vector{Union{UInt64,String}} for representing the pre/pld information?

[topolarity]

I believe these are considered public constructors at this point, so I'm not sure we have the freedom to do that

[jakobnissen]

This was made public in #50179 where it was (apparently) explicitly decided that it should stay a Tuple

[mcabbott]

FWIW, a quick attempt to time this... maybe you have a better measurement in mind, as part of something larger?

julia> @btime tryparse(VersionNumber, $("2.0.1-rc1"))  # master
  min 915.300 ns, mean 1.011 μs (17 allocations, 744 bytes)
v"2.0.1-rc1"

julia> @btime tryparse(VersionNumber, $("2.0.1-rc1"))  # with PR
  min 866.673 ns, mean 959.908 ns (16 allocations, 728 bytes)
v"2.0.1-rc1"

julia> @btime tryparse(VersionNumber, $("2.0.1-rc1"))  # with PR + LazyString for all error messages
  min 862.069 ns, mean 943.470 ns (16 allocations, 728 bytes)
v"2.0.1-rc1"

[topolarity]

The major improvement is in compile-time for varied VersionStrings:

julia> version_strings = String[]

julia> for i = 1:1000
           version = "2.0.1"
           prerelease_segments = rand(0:5)
           if prerelease_segments > 0
               segments = ntuple(_->rand(Bool) ? string("rc") : string(rand(1:10)), prerelease_segments)
               version *= "-" * join(segments, ".")
           end
           # version = "2.0.1" or "2.0.1-rc.2" or etc.
           push!(version_strings, version)
       end

julia> @time for s in version_strings
            Base.tryparse(VersionNumber, s)
       end
  0.001412 seconds (18.53 k allocations: 837.891 KiB)

versus on 1.10:

julia> @time for s in version_strings
            Base.tryparse(VersionNumber, s)
       end
  0.745204 seconds (760.38 k allocations: 53.482 MiB, 1.33% gc time, 98.82% compilation time)

a 500x improvement