Fix static dispatch allowing methods with unconstrained generic first param #9027
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… param When calling a method via static dispatch syntax (e.g., `lst.repeat(3)`), the compiler should verify that the method's first parameter type is compatible with the receiver type. Previously, methods like `List.repeat : a, U64 -> List(a)` could be called via `lst.repeat(3)` where `lst : List(b)`, even though `repeat` has a generic first parameter `a` that doesn't specifically accept List values. This fix adds a check during deferred static dispatch constraint resolution that validates the method's ORIGINAL first parameter type (before instantiation). For builtin methods, if the first parameter is an unconstrained rigid type variable (from an explicit annotation), the call is rejected with a MISSING METHOD error. Valid cases still work: - First param is the nominal type itself (e.g., `len : List(_) -> U64`) - First param is a constrained type variable (e.g., `a where [a.method]`) - First param is inferred (flex) from a lambda without annotation Fixes #9019 Co-Authored-By: Claude Opus 4.5 <[email protected]>
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Summary
This PR fixes a bug where static dispatch syntax (e.g.,
lst.repeat(3)) allowed calling methods whose first parameter type doesn't match the receiver type. Specifically,List.repeat : a, U64 -> List(a)could be called on a List even though its first parameter is a genericathat doesn't specifically accept List values.Fixes #9019
Co-authored by Claude Opus 4.5