[ASDAlexander77]

Follow-up to #425, which left let x = p.length; x = -1; printing 4294967295.

What was wrong

An index (a length) already compares as signed (for (let k = s.length - 1; k >= 0; k--) stops) and converts to number as signed (sitofp). Two places disagreed:

• si32 -> index zero-extended. The cast fell through to the generic ZExtOp in castLLVMTypesLogic, so n = -1 stored 0x00000000FFFFFFFF. n == -1 was still true, since the literal was cast the same way, but const v: number = n was 4294967295. It now sign-extends.
• index -> string printed unsigned. s.length - 3 printed 18446744073709551615 though s.length - 3 < 0 was true. It now prints -1.

Before / after (s = "ab", a = [1, 2]):

expression	before	after
let n = s.length; n = -1; print(n)	4294967295	-1
const v: number = n	4.29497e+009	-1
`${s.length - 3}`	18446744073709551615	-1
let w = a.length; w -= 5	18446744073709551613	-3
const b: any = n; print(b)	4294967295	-1

Trade-off: a length of 2^63 or more (2^31 on x86) would print negative. No real length gets that large.

Not changed

• A user-declared signless i32 still prints unsigned (let i: i32 = 5; i = i - 6 prints 4294967295). u32 printing 4294967295 for 5 - 6 is correct.
• let y = 1; y = 0.5 prints 0: integer literals are s32 by design.

Tests

• New 00length_signed_arithmetic.ts (compile + jit): assignment, number / text / any conversion, length subtraction, --, -=, countdown loop.
• Release suite: 3337/3337 passed (one test disabled, as before).
• DefaultLib (main b67a213) rebuilt release/gc with this compiler: 158/158 compile, 158/158 jit.
• Not run: Debug, other memory models, x86.

🤖 Generated with Claude Code