Files
sx/examples/0207-generics-value-param-const.sx
agra a491a1bf73 fix(ir): route every comptime-int through the shared evaluator (0083)
Attempts 1–4 fixed the array-dimension paths but the same length-0
fabrication class survived on every other site that resolves a
compile-time integer. Unify them all on the single shared
`program_index.evalConstIntExpr` so they cannot diverge:

- All three Vector lane resolvers (resolveTypeCallWithBindings,
  resolveParameterizedWithBindings, resolveArrayLiteralType) and both
  generic value-param binders (instantiateGenericStruct,
  instantiateTypeFunction) hand-rolled an `else => 0` switch. A
  module-const lane `Vector(N, f32)` fabricated a 0-lane `<0 x float>`
  (LLVM "huge alignment" abort); a value-param `Vec(N, f32)` fabricated
  a 0 binding / wrong mangled name. They now fold through the shared
  evaluator and emit a clean diagnostic + `.unresolved` on a non-const
  operand (resolveVectorLane / resolveValueParamArg) — never 0.
- evalComptimeInt (inline-for bounds) delegated to the shared evaluator,
  so `inline for 0..M` / `0..(M+1)` fold like array dims. The `<pack>.len`
  leaf moved into the shared folder via a new `ctx.lookupPackLen`.
- The unknown-type semantic checker no longer walks a value-param
  position (`Vector(N, …)` / `Vec(N, …)`) as a type name (was reporting
  "unknown type 'N'").
- The parameterized-type-arg parser and the function-body lookahead
  (hasFnBodyAfterArrow) accept a const-EXPRESSION in a value position, so
  `Vector(M + 1, f32)` and `[M + 1]T` parse as a return type too (the
  latter a pre-existing array-dim sibling that the same heuristic broke).

Regressions: examples/1501 (named-const + const-expr lane, direct +
alias, 3/4-lane reads), 1502 (runtime lane clean-halts, exit 1, no LLVM
crash), 0207 (Vec(N)/Vec(M+1) == Vec(3) instantiation), 0610 (inline-for
const bounds). Shared-evaluator unit test extended with the pack-len arm.

zig build && zig build test && bash tests/run_examples.sh: 395 passed,
0 failed.
2026-06-04 11:32:25 +03:00

30 lines
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// A generic value parameter (`$K: u32`) bound from a named const or a
// constant-foldable expression resolves to the SAME monomorphised instantiation
// as the literal form: `Vec(N, f32)` (N a module const) and `Vec(M + 1, f32)`
// (a const expression) are both `Vec(3, f32)`. The struct-copy assignment is the
// proof — it type-checks only because the two spellings name one instantiation.
//
// Regression (issue 0083): the value-param binder hand-rolled an `else => 0`
// switch, so a named-const value arg either fabricated a 0 binding under a wrong
// mangled name or was rejected outright as "unknown type 'N'". It now folds
// through the shared const-int evaluator (`program_index.evalConstIntExpr`).
#import "modules/std.sx";
N :: 3;
M :: 2;
Vec :: struct ($K: u32, $T: Type) { data: [K]T; }
main :: () {
a : Vec(N, f32) = ---; // named-const value param
a.data[0] = 10.0; a.data[1] = 20.0; a.data[2] = 30.0;
print("named: len={} a0={} a2={}\n", a.data.len, a.data[0], a.data[2]);
e : Vec(M + 1, f32) = ---; // const-expr value param (M + 1 == 3)
e.data[0] = 1.0; e.data[2] = 9.0;
print("expr: len={} e2={}\n", e.data.len, e.data[2]);
b : Vec(3, f32) = a; // same instantiation → struct copy type-checks
print("copy: len={} b2={}\n", b.data.len, b.data[2]);
}