"for" does not validate variable names

[0ion9]

for a,b in y 1 z 3; echo $a,$b; end

Expected result: either an error or (ideally) setting a=y b=1, iterating once, then setting a=z b=3; printing each of those pairs on its own line.

Actual result: 4 blank lines

Proof of what is actually happening:

for a,b in y 1 z 3; set -l; end

Result:

a,b y
a,b 1
a,b z
a,b 3

In other words, for is assigning to a variable named "a,b".

This variable cannot be expanded (echo $a,b expands correctly to nothing ($a is not set, and therefore the product of it with ",b" is nothing)), nor can the user set, query, or erase this variable.

---

fish version 3.0.2-824-gbf40f84b0

[0ion9]

List of invalid characters that for accepts in a variable name:

,-!$#%^&*()=+[]
;:"/?.><|\`~

So, basically all of them, and in any position (for example for , in 1 2 3; set -l;end)

[floam]

Yeah, that's a bug. It actually is created, too, neat:

$ for a,b in a;
    set|grep 'a,b'
  end
a,b a

[floam]

fixed:

$ for a,j in i v; echo foo; end
fish: invalid var name: a,j
for a,j in i v; echo foo; end
    ^