scalar family constraints for struct fields

2026-07-13 23:00:42 +02:00
parent 6de4d9f9f3
commit 0eeacc2e37
3 changed files with 585 additions and 12 deletions
@@ -39,6 +39,20 @@ roadmap and milestone history.
 - native sum composition with `A | B` for unbacked enums and tagged unions, using program-global `u16` variant ids
 - fallible channel types `T ! E`, where `E` is a native enum/tagged union or supported sum composition

+#### native record constraint fields
+
+A direct `int`, `float`, or `range` field in a named native struct or union is a
+program-wide constraint, not per-value polymorphism. Before record layout, all reachable keyed
+constructors, field assignments, and concrete uses of field reads contribute demands and the field
+resolves once to one concrete runtime type. Compatible scalar demands widen normally. Integer
+literals remain provisional until inference settles, so a later `usize` use can resolve an `int`
+field to `usize`; otherwise literal-only `int` fields use the widest smallest-signed type required,
+and literal-only `float` fields use `f64`.
+
+An undemanded field or incompatible demands are errors. This inference applies only to direct
+fields of named native records. `c_struct` fields, nested constraints such as `[]int`, and fields in
+anonymous generated records still require concrete runtime types.
+
 #### keyword member names

 Reserved keywords are valid native enum members and tagged-union variants when used in an