`type TIdx = lo..hi; TBuf = array[TIdx] of T;` now resolves to
`array[lo..hi] of T`, parallel to the existing `array[TEnum] of T`
ordinal-index folding. Previously a named subrange used as an array
index was rejected with "'TIdx' is not an enumeration type", because a
subrange was stored as a transparent alias to its narrowest standard
integer type with its bounds discarded, and the array-index resolver
only accepted enum index types.
A named subrange now keeps its lo..hi bounds as compile-time metadata on
a DISTINCT TTypeDesc (IsSubrange/SubrangeLow/SubrangeHigh). Its storage
and ABI are unchanged — it is still its underlying narrowest int, values
behave as ordinary unchecked integers (Blaise does no range checking) —
only the array-index resolver consults the retained bounds, folding
array[TIdx] to array[lo..hi]. Low/High on such an array then work via
the folded static-array bounds.
The bounds round-trip through the .bif META 'alias' record (three
trailing fields after TypeName), so a subrange exported from a unit and
used as `array[OtherUnit.TIdx]` resolves correctly across separate
compilation. IFACE_VERSION 7 -> 8 (the alias record grew; v7 readers
must reject and recompile). CloneTypeDef copies the new fields so the
export/clone path does not drop IsSubrange.
Tests: two e2e cases (0-based and 2..4 non-zero base, asserting element
reads + Length/Low/High on every backend), two IR/semantic cases
(the index folds to the right static-array bounds), and a .bif
round-trip case (IsSubrange + bounds survive write->read); the
magic/version assertion updated to v8.
1035dcc1c9