Eval Binding Fixes #

Status: completed Last reviewed: 2026-09-10 Owner: theMackabu

Historical implementation record extracted from the execution-plan index. The validation below was recorded during implementation, not rerun during the documentation cleanup.

Outcome And Decisions #

• typeof arguments skips the implicit object when the function owns an eval environment, retaining the existing undefined-safe lookup fallback.
• The eval pre-scan checks parameter patterns and scoped body declarations before deciding owns_eval_env. Body bindings do not shadow parameter initializers; block, loop, catch, and switch bindings do not hide calls outside their scope. Static local/upvalue and spread eligibility checks remain in place.
• Inherited eval calls resolve the callee before arguments and compare it with the named builtin installed by global initialization (js_builtin_eval). Arguments are emitted once with the identity flag above them on the stack; dispatch selects an ordinary call or OP_EVAL. This uses existing opcodes. Inherited builtin calls use runtime eval rather than literal inlining.

Recorded Validation #

The saved pre-fix binary failed all eight core parameter/body-shadowing cases with value undefined. Its nested-bytecode regression grew from 541 to 8,941 bytes at depths 4 and 8. The fixed function grew linearly: 148, 280, and 412 bytes at depths 4, 8, and 12.

Focused eval regressions passed, including scope-boundary and argument-effect controls. The full spec suite passed 4,221 tests across 102 files. Repository preflight and diff checks passed.

Original Record #

git show bc206f10a9ea73d3d91302eb208adf1479e4d22e:docs/exec-plans/index.md