Bug 4695 – std.range.zip is broken

import std.range; void main() { auto a = [ 1, 2, 3 ]; immutable b = [ 1, 2, 3 ]; zip(a, b); } outputs: src/phobos/std/range.d(1732): Error: can only initialize const member _field_field_1 inside constructor import std.range; void main() { auto a = [ 1, 2, 3 ]; auto b = [ 'a', 'b', 'c' ]; zip(a, b); } outputs: src/phobos/std/range.d(1773): Error: front(this.ranges._field_field_1) is not an lvalue

Thanks for the report. I just wanted to note that this is more of a design issue than an implementation bug. The lack of tail const makes making higher order ranges work properly for const/immutable ranges impossible except in some special cases. (const/immutable arrays are one of these special cases.) This flaw may eventually get fixed, or we may eventually special case everything to work with at least const/immutable arrays, but there are deeper issues that need to be resolved before this gets fixed.

Works on 2.059

While the general problem is not solved, this specific problem with arrays is solved.