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ww/test/lang/letshadow_test.ww
Hojun-Cho 99b98b9b1b test: migrate 989_letshadow to @test value pin, retire C twin (fold-3)
#152 link-the-let-before-its-init miscompile (miscompiled IDENTICALLY on both stages, so byte-id 990-997 was blind; only a runtime value check catches it). Lifted the run fixture into test/lang/letshadow_test.ww (primitive @test value pin; byteid-eligible — symmetric, cs==ww). byteid floor 56->57. Closes the fold-3 #7 umbrella (last C test twin retired).
2026-06-22 18:30:04 +09:00

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// letshadow_test — #152 regression pin, migrated from test/wcc/989_letshadow_run.c.
//
// A `let` binding must NOT be visible during its OWN initializer:
// `let x = f(x)` evaluates f(x) in the OUTER scope (Hare: harec check.c clet
// runs cexpr before scope_define). Both stages once linked the binding into
// the cgen localfind chain BEFORE emitting the init, so the init read the
// fresh UNINIT shadow slot — a silent miscompile IDENTICAL on both stages
// (byte-id was GREEN over it), now fixed. PRIMITIVE-only (i32) asserts.
package letshadow_test;
fn id(s: str) str = { return s; };
// Row 1 — PARAM self-shadow (ken's headline, the c3-posix shape):
// `let p = id(p)` must read the PARAM p, not the uninit shadow.
// "hello" → len(5)*100 + 'h'(104) = 604 (pre-fix: 0, the zero slot).
fn paramshadow(p: str) i32 = {
let p = id(p);
return (p.len: i32) * 100 + (p[0]: i32);
};
// Row 2 — LET shadows an OUTER-scope LET in its OWN init. ww rejects
// same-block redeclaration, so the inner let lives in a nested block;
// its init must read the OUTER x (=5) since the inner x isn't linked
// yet → 6 (pre-fix: garbage from the fresh uninit shadow slot).
fn letinletinit() i32 = {
let x: i32 = 5;
let r: i32 = 0;
{
let x: i32 = x + 1;
r = x;
};
return r;
};
// Row 3 — CONTROL (rename, no shadow). Already correct both pre/post;
// pins no-regression. "hi" → 2.
fn renamecontrol(p: str) i32 = {
let p2 = id(p);
return p2.len: i32;
};
// Row 4 — UNIFORM-arm proof: arrlit self-ref. The inner `let a = [a, a]`
// (nested block; ww rejects same-block redeclaration) shadows the outer
// a; both elements must read the OUTER a (=3) → 6. Proves the N_ARRLIT
// arm defers the link too, not just the value-init arm.
fn arrlitselfref() i32 = {
let a: i32 = 3;
let r: i32 = 0;
{
let a: [2]i32 = [a, a];
r = a[0] + a[1];
};
return r;
};
@test fn param_self_shadow() void = {
assert(paramshadow("hello") == 604i32);
};
@test fn let_in_let_init() void = {
assert(letinletinit() == 6i32);
};
@test fn rename_control() void = {
assert(renamecontrol("hi") == 2i32);
};
@test fn arrlit_self_ref() void = {
assert(arrlitselfref() == 6i32);
};