Relax opinion on use of `;` in NamedTuples?

[nickrobinson251]

Current guidnace is "NamedTuples should not be prefixed with ; at the start" (related to https://github.com/invenia/BlueStyle/pull/22)

As the current examples show this leads to these three cases having different style:

xy = (x=1, y=2)
x1 = (x=1,)  # Trailing comma required for correctness.
xs = (; kwargs...)  # Semicolon required to splat correctly.

I can't help but feel that this is a simpler rule:

xy = (; x=1, y=2)
x1 = (; x=1,) 
xs = (; kwargs...) 

Also, I write a lot of code in codebases that follow BlueStyle and I don't recall anyone ever corrected me on adding/removing a ;, so i wonder how much this guidance is even followed right now.

(related to #7, https://github.com/domluna/JuliaFormatter.jl/issues/283#issuecomment-687815553)

[nickrobinson251]

Existing guidance

# Yes:
xy = (x=1, y=2)
x = (x=1,)  # Trailing comma required for correctness.
x = (; kwargs...)  # Semicolon required to splat correctly.

# No:
xy = (x = 1, y = 2)
xy = (;x=1,y=2)
x = (; x=1)

Suggested change to

# Yes:
xy = (; x=1, y=2)
x = (; x=1,)  
x = (; kwargs...) 

# Ok:
xy = (x=1, y=2)

# No:
xy = (x = 1, y = 2)
xy = (;x=1,y=2)

[omus]

My preference is to not use the semi-colon. You are correct in that the rule is more straight forward with always including the semi-colon but the only case it's required is for splatting so really we're just enforcing the use of two extra characters to gain a little extra consistency. Most people probably don't encounter (; kwargs...) which is why I'm good with leaving things as they are.

[jonniediegelman]

IMO the no-semicolon version is somewhat unsafe due to how easy it is to forget a trailing comma on a single-element NamedTuple. This has been a pretty persistent and difficult-to-resolve source of bugs in our code base. My opinion is that leading semicolons in NamedTuples should at least be in the Ok section, if not the Yes.