Files
sx/examples/0770-modules-type-fn-head-non-transitive.sx
agra 94c3cd7507 fix(stdlib/E4): kind-aware type-fn head gate (non-fn must not vouch)
The type-fn head visibility check (`headFnLeak`) used the module-scope
NAME predicate `isNameVisible`, so a same-name 1-hop NON-function (a value
const `Make :: 123`) reported the name "visible" and let the global
`fn_ast_map` type-fn — whose real author is 2 flat hops away — silently
instantiate. `size_of(Make(s64))` printed 8 at exit 0 instead of a
visibility diagnostic.

Decide visibility from the ELIGIBLE FUNCTION authors directly reachable
from the use site (`flatFnAuthorVisible`, mirroring `flatFnAuthorAmbiguous`'s
fn-only author view): visible iff the own author or a 1-hop flat-import
author is a `fn_decl`. A non-function does not vouch. Guarded to fall open
when the import facts aren't wired (comptime / directory imports), mirroring
`headTypeGate`. Own / scope-local / 1-hop / directly-imported type-fn heads
still resolve; 0769 ambiguity unchanged.

Regression: examples/0770-modules-type-fn-head-non-transitive (main → b
[`Make :: 123` + flat-imports c] → c [`Make :: ($T) -> Type`]); the bare
`Make(s64)` head emits "type 'Make' is not visible", exit 1.
2026-06-08 16:03:23 +03:00

24 lines
1.1 KiB
Plaintext

// A type-returning FUNCTION head (`Make(s64)` where `Make :: ($T) -> Type`) is
// NON-transitive even when a DIRECT flat import authors the same name as a
// NON-function. `main` flat-imports `b.sx`; `b.sx` declares `Make :: 123` (a
// value const, not a type-fn) AND flat-imports `c.sx`, whose `Make` IS the
// type-returning function. The only TYPE-FN author of `Make` is two flat hops
// away (main → b → c), so the bare `Make(s64)` head must emit the
// "type 'Make' is not visible" diagnostic and poison — the visible 1-hop
// `Make :: 123` const must NOT vouch for it.
//
// Regression (Phase E4 attempt-7, finding E4-type-fn-head-hidden-by-visible-
// nonfn): before `headFnLeak` decided visibility from the ELIGIBLE FUNCTION
// authors it used the module-scope NAME predicate (`isNameVisible`), which the
// visible non-fn `Make :: 123` satisfied — so the global `fn_ast_map` type-fn
// silently instantiated and `size_of(Make(s64))` printed 8 at exit 0 instead of
// the visibility diagnostic.
#import "modules/std.sx";
#import "0770-modules-type-fn-head-non-transitive/b.sx";
main :: () -> s32 {
print("size={}\n", size_of(Make(s64)));
0
}