19bc644b11
A protocol-constrained pack element exposes only the constraint protocol's interface (the locked decision): `xs[i].<member>` is rejected unless `<member>` is one of the protocol's methods. `xs[i].v` (a concrete field of IntCell, not declared on Box) now errors, like a constrained generic — even though the substituted element is concretely an IntCell. monomorphizePackFn records the pack param's constraint protocol in a new `pack_constraint` map (pack-name → protocol); lowerFieldAccess checks it on an `xs[i]` (index_expr) base BEFORE substitution erases the "constrained to P" context. Protocol method calls (`xs[i].get()`) pass — the name is in the protocol. Regression: examples/195-pack-interface-only.sx.
6 lines
262 B
Plaintext
6 lines
262 B
Plaintext
error: 'v' is not part of protocol 'Box' — a pack element exposes only the protocol's interface
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--> /Users/agra/projects/sx/examples/195-pack-interface-only.sx:16:12
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16 | return xs[0].v; // `v` is not part of Box — error
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| ^^^^^^^
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