Lyric

What changed in v2.0.1 — 2026-08-20

The first harvest of the deep audit: seven bugs measured against the now-normative specification, fixed as one wave. Seven new conformance cases activate with this release (//! since: 2.0.1); the suite stands at 78.

Fixed

• a..=hi reaches the type's maximum. The inclusive range desugared to ..hi+1, which wraps at the bound — for (_ in max-2..=max) ran ZERO times. Inclusive ranges ride their own adapter with a done flag now; no arithmetic touches the bound.
• Ranges over every width and signedness. A range over uint8/int16/… produced malformed IR that only the Release verifier-skip let run; a uint range crossing 2⁶³ compared SIGNED and ran dry. Bounds now widen into a signed or unsigned carrier, and the loop variable converts back at its own width.
• defer belongs to the block. A defer in a loop body registered once into the function scope: it fired once, with the last iteration's values, after the code following the loop. Loop bodies are scopes now — the defer runs at every iteration's end, continue and break included, draining exactly the scopes being left.
• let x = null; and let xs = []; report instead of crashing. Both drove an unhandled internal exception through the lowering. They are LYR-SEM0010 now: the initializer fixes no type, the binding needs an annotation.
• An oversized literal no longer reinterprets. let x = 9223372036854775808; compiled and held −9223372036854775808 — the magnitude's raw bits. A literal that stays at the default int must fit int; the same magnitude still adapts to annotated uint positions.
• An integer literal meets a float exactly. let g: float = 9007199254740993; (2⁵³+1) adapted with a silent rounding; "fits" is exact now, for float and float32 alike.
• A throws clause on main is refused (LYR-SEM0021). It compiled, and a thrown exception left the program as the LYR-VM0010 panic the specification calls unreachable from source.

Improved

• "cannot assign 'T' to 'T'" names its cause: when the two displays collide, the message says the types differ by identity — declared in different scopes, or a generic call instantiating itself at a larger type, which monomorphization refuses.
• A contextless generic construction reports LYR-SEM0026 once, without a follow-up "cannot assign" per field.
• A new test pins the §11 contract: every native the shipped stdlib declares is bound by the default registry (std.build excepted — the build runner is its host, now said in §11).

The full changelog →