Accept a nested target as the first for loop index#4156
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A `for` loop index may be a multiple-assignment target whose first
element is itself a parenthesized (nested) target, e.g.
for (a, b), c in 1..10
end
CRuby's parse.y accepts this, and a plain multiple assignment with the
same target (`(a, b), c = ...`) is accepted, but Prism rejected it with
"unexpected write target".
When parse_parentheses finishes the first `(a, b)`, it validates the
multi-target it produced. In a `for` index it only allowed the target
to be followed by `in`, so a following `,` (which continues the index
target list) fell through to the "not a statement level" error. Allow
a comma there as well.
shugo
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kddnewton
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Jul 6, 2026
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A
forloop index may be a multiple-assignment target whose first element is itself a parenthesized (nested) target, e.g.CRuby's parse.y accepts this, and a plain multiple assignment with the same target (
(a, b), c = ...) is accepted, but Prism rejected it with "unexpected write target".When parse_parentheses finishes the first
(a, b), it validates the multi-target it produced. In aforindex it only allowed the target to be followed byin, so a following,(which continues the index target list) fell through to the "not a statement level" error. Allow a comma there as well.