Shadowed names provide very unhelpful error messages #48

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opened 2026-07-20 11:50:54 +02:00 by st · 0 comments

st commented

2026-07-20 11:50:54 +02:00

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Repro of the smell (current behavior):
  use std/Eq
  Eq.eq(3, 3)        # → "error: unbound variable 'Eq.eq'"
`use std/Eq` imports the MODULE Eq, shadowing the prelude's INTERFACE Eq; `eq` isn't a
module member, so it should be a clean resolve error, but resolve emits an optimistic
MemberRef and infer reports it. (Without the `use`, Eq.eq works fine — generalization is
not the issue.)

Root: resolve.mli:1 states "every name reference is classified by its binding category,"
but qualified `Mod.member` violates it. resolve's module namespace is PUBLIC-ONLY
(module_sig_names filters private, types.ml:~241), so resolve can't tell "absent" from
"private" and defers both (ARModule branch resolve.ml:~768-799 → qualified_binding
~691). Infer does the real check at infer.ml:~1438-1445 against the full sig
(module_sig.members keeps visibility). Visibility is SYNTACTIC (pub/private), so giving
resolve visibility does NOT re-couple to inferred sigs — the phase separation is about
inferred TYPES only.

``` Repro of the smell (current behavior): use std/Eq Eq.eq(3, 3) # → "error: unbound variable 'Eq.eq'" `use std/Eq` imports the MODULE Eq, shadowing the prelude's INTERFACE Eq; `eq` isn't a module member, so it should be a clean resolve error, but resolve emits an optimistic MemberRef and infer reports it. (Without the `use`, Eq.eq works fine — generalization is not the issue.) Root: resolve.mli:1 states "every name reference is classified by its binding category," but qualified `Mod.member` violates it. resolve's module namespace is PUBLIC-ONLY (module_sig_names filters private, types.ml:~241), so resolve can't tell "absent" from "private" and defers both (ARModule branch resolve.ml:~768-799 → qualified_binding ~691). Infer does the real check at infer.ml:~1438-1445 against the full sig (module_sig.members keeps visibility). Visibility is SYNTACTIC (pub/private), so giving resolve visibility does NOT re-couple to inferred sigs — the phase separation is about inferred TYPES only. ```