fixes#17958
In `transf`, conversions in subscript expressions are skipped (with
`skipConv`'s rules). This is because array indexing can produce
conversions to the range type that is the array's index type, which
causes a `RangeDefect` rather than an `IndexDefect` (and also
`--rangeChecks` and `--indexChecks` are both considered). However this
causes problems when explicit conversions are used, between types of
different bitsizes, because those also get skipped.
To fix this, we only skip the conversion if:
* it's a hidden (implicit) conversion
* it's a range check conversion (produces `nkChckRange`)
* the subscript is on an array type and the result type of the
conversion has the same bounds as the array index type
And `skipConv` rules also still apply (int/float classification).
Another idea would be to prevent the implicit conversion to the array
index type from being generated. But there is no good way to do this:
matching to the base type instead prevents types like `uint32` from
implicitly converting (i.e. it can convert to `range[0..3]` but not
`int`), and analyzing whether this is an array bound check is easier in
`transf`, since `sigmatch` just produces a type conversion.
The rules for skipping the conversion could also receive some other
tweaks: We could add a rule that changing bitsizes also doesn't skip the
conversion, but this breaks the `uint32` case. We could simplify it to
only removing implicit skips to specifically fix#17958, but this is
wrong in general.
We could also add something like `nkChckIndex` that generates index
errors instead but this is weird when it doesn't have access to the
collection type and it might be overkill.
fixes#17163, refs #23204
Types that aren't `tyRange` and are bigger than 16 bits, so `int32`,
`uint64`, `int` etc, are disallowed as array index range types.
`tyRange` is excluded because the max array size is backend independent
(except for the specific size of `high(uint64)` which crashes the
compiler) and so there should still be an escape hatch for people who
want bigger arrays.
* clean up some test categories
* mention exact slice issue
* magics into system
* move trangechecks into overflow
* move tmemory to system
* try fix CI
* try fix CI
* final CI fix
* add `isNamedTuple`; make $(1, 2) be (1, 2) instead of leaking implementation detail (Field0: 1, Field1: 2)
fixes this: #8670 (comment) /cc @alehander42 @Vindaar @mratsim
* Note: isNamedTuple is useful in other places, eg #10010 (comment)
* move isNamedTuple to helpers.nim to avoid exposing new symbol to system.nim
* remove workaround in tests/vm/tissues.nim failing test now that #10218 was makes it work
