Add public to the @compat macro

[LilithHafner]

The documentation included in this PR should make the PR itself self-explanatory. If it's not self-explanatory, then it's not acceptably documented.

[codecov]

Codecov Report

Merging #805 (d74c2f3) into master (c59d116) will increase coverage by 0.41%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #805      +/-   ##
==========================================
+ Coverage   92.72%   93.13%   +0.41%     
==========================================
  Files           2        2              
  Lines         316      335      +19     
==========================================
+ Hits          293      312      +19     
  Misses         23       23              

Files Changed	Coverage Δ
src/Compat.jl	93.22% <ø> (ø)
src/compatmacro.jl	92.50% <100.00%> (+6.78%)	⬆️

[fredrikekre]

Can I propose @compat public foo, bar?

[LilithHafner]

Is @compat already used or would this be the only non-deprecated use of the @compat macro?

[fredrikekre]

It used to be used for all these kind of things in the past, and it is still there:

Compat.jl/src/compatmacro.jl

Line 26 in c59d116

macro compat(ex)

[LilithHafner]

IIUC @compat was used for syntax changes in the pre-1.0 erra, and was rendered a no-op when Compat.jl dropped support for pre-1.0 code? If that history is correct, then @compat public foo, bar seems appropriate.

[fredrikekre]

But that was because Compat.jl dropped support for pre Julia 1.0, no? Then there was no point in having all the old syntax transformations.

[LilithHafner]

@fredrikekre, I think we are in agreement. I also prefer your proposed syntax. We should probably wait at least a day or so to let other folks chime in, though.

[mcabbott]

This does not seem to allow macros:

julia> @compat public fun, @mac
ERROR: LoadError: ArgumentError: cannot mark `(fun, #= REPL[15]:1 =# @mac())` as public. Try `@compat public foo, bar`.

[LilithHafner]

Should this be backported to 3.x?

[lgoettgens]

Should this be backported to 3.x?

I would be in favor of this. There are many packages out there that support julia versions older than 1.6 and are thus unable to depend on Compat 4.
Personally, I would really like to use @public via a Compat-compatible way in Aqua.