A protocol method reads its fields through the generic guarded keyword lookup
because the method's `this` param is untyped. defrecord now hints `this` with
the record type, the per-form inference seeds ^Record-hinted params (the
:fn branch previously typed all params :any — only the whole-program path
seeded phints), and run-passes feeds the inference the record shapes. So a
hinted param's field reads bare-index instead of going through the :jolt/type
tag guard.
This needed a with-meta fix: (with-meta sym ..) returned a proto'd table, so
symbol? was false and the macro-attached hint broke fn destructuring. Symbols
now carry metadata in-place in their struct (matching how the reader attaches
^hint), keeping symbol? true, as in Clojure.
Modest on dispatch (~3-5%): the field read is a small fraction of a dispatch;
the machinery (record-tag + protocol lookup + wrapper) dominates, which is the
inline-cache target (jolt-ez5h). But it's a correctness fix and lets any
^Record-hinted code — not just methods — drop the field-read guard per-form,
not only under whole-program.
Co-authored-by: Yogthos <yogthos@gmail.com>
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