Minor fix for long form anonymous functions

[ghost]

Minor fix for #32557. Return type declarations for the long form anonymous functions now return ERROR.

julia> f = function(x)::Int
                  x/2
              end
ERROR: syntax: invalid "::" syntax
Stacktrace:
 [1] top-level scope at REPL[1]:1

To support for the return type declarations, we might have to change the definition of "function" in AST.

[JeffBezanson]

To minimize breakage, I think the right thing here might be to give a clear warning like "this use of :: declares the type of the argument, but in the future may change to declare a return type instead".

[JeffBezanson]

Triage thinks we should run PkgEval on this and see if anybody is using this syntax before making a decision.

[JeffBezanson]

@nanosoldier runtests(ALL, vs = ":master")

[nanosoldier]

Something went wrong when running your job:

NanosoldierError: failed to run tests against primary commit: UndefVarError: LibGit2 not defined

Logs and partial data can be found here
cc @maleadt

[maleadt]

@nanosoldier runtests(ALL, vs = ":master")

[nanosoldier]

Something went wrong when running your job:

ProcessExitedException(2)

cc @maleadt

[maleadt]

Server crashed.
@nanosoldier runtests(ALL, vs = ":master")

[nanosoldier]

Your test job has completed - possible new issues were detected. A full report can be found here. cc @maleadt

[JeffBezanson]

Nice! One thing we find out from PkgEval is that the anon flag used here (which, note, was not used at all in parse-def before) is not entirely accurate. It triggers an error on this case:

function (+)(p::CartesianPoint{T}, v::CartesianVector{T})::CartesianPoint{T} where {T <: Real}

where this initially looks like it might be an anonymous function since the signature begins with (. So this will need a bit more work.

[rfourquet]

Is something blocking this PR?

[JeffBezanson]

Yes, see my previous comment. This causes errors on previously valid signatures.

[DilumAluthge]

It looks like this pull request is no longer mergeable.

If you would still like to make this change, please make a new pull request based on the latest master branch of Julia.