unit-scoped operator definitions silently skipped → record binop miscompile

• Type: bug (compiler core / shared parser.inc + ir.inc) — Track A
• Status: done [[feature-pascal-operator-decl-fpc-compat]] (found the moment a unit-scoped operator was tried; pre-existing — pinned stable segfaults too). Self-resolved same session under combined P+A assignment.
• Owner: fable-p

Symptom

Any operator definition in a unit's implementation section was silently skipped: the impl decl loop in ParseUnit (parser.inc ~17406) had no operator dispatch, so the whole definition fell through else Next token-by-token. No overload was registered; a + b on records then fell through to the scalar IR_BINOP, adding the records' first qwords and using the sum as a copy source → SIGSEGV at run time (rep movsb with the record VALUE in rsi). Program-scoped operators were fine (top-level decl loop has the dispatch).

Fix

1. ParseUnit impl loop: dispatch 'operator' → PreScanPass := False; ParseOperatorDef; PreScanPass := True (same emit-in-place pattern as the top-level loop and initialization).
2. ir.inc binop lowering: arithmetic op (+ - * / div mod) on a record operand with no registered overload is now a compile error instead of a silent scalar-binop miscompile. Comparisons left alone (method-pointer =/<> are legitimate record compares).

Note: an interface-section operator heading is still skipped silently (the overload table is global, so the implementation's registration is visible everywhere; FPC-style interface-gated visibility is not modeled). An interface-only decl with no implementation now errors at the use site via (2).

Known limitation: the operator body is emitted during the unit's prescan, so it can only call impl routines declared ABOVE it (same as initialization ordering rules — fine in practice, operators sit near the top).

Gate

make test + self-host fixedpoint byte-identical. Tests: test/test_op_fpc_named_result.pas (program) + unit-scoped operator test.

Log

• 2026-07-11 — resolved, commit a384369a.