local "_" declared twice

[Christoph Ortner]

Is this intended behaviour or a bug? 

julia> maximum( t for (t,_,_) in zip(x,y,z) )
ERROR: syntax: local "_" declared twice


julia> x = rand(3); y = rand(3); z = rand(3);


julia> for (t, _, _) in zip(x, y, z)
                  println(t)
              end
0.5059694701992228
0.6291609082858327
0.298657434448903


julia> maximum( t for (t,_,_) in zip(x,y,z) )
ERROR: syntax: local "_" declared twice

[Stefan Karpinski]

It's intentional, but maybe using `_` twice should be allowed?

[Christoph Ortner]

I am only confused because

for (t, _, _) in zip(x, y, z)

is fine while

maximum( t for (t,_,_) in zip(x,y,z) )

is not.

[Stefan Karpinski]

If you could post clarification here: https://github.com/JuliaLang/julia/issues/18251.