Issues

JSON.parse error message omits the position (line/column/offset) that other engines include

#10882

· steinybot opened

on Sep 21, 2026

Object.prototype members are invisible to property reads and `in` unless the program names `Object.prototype` (`"toString" in {}` is false)

#10880

· proggeramlug opened

on Sep 21, 2026

PERRY_DELETE_SHAPE_TRANSITION=0 is unsound now that the property ICs no longer test slots for TAG_HOLE — retire the kill switch (#10826 own note asked for it; the store tower now depends on it too)

#10879

· proggeramlug opened

on Sep 21, 2026

A property miss is GEOMETRIC in prototype-chain depth (x2.1/level): 536,047 instructions for one absent read on an 8-deep chain

#10877

· proggeramlug opened

on Sep 21, 2026

runtime: resizable ArrayBuffer unimplemented — `new ArrayBuffer(n, { maxByteLength })` ignores the options, `.resize()` is not a function

#10873

· proggeramlug opened

on Sep 21, 2026

perf: layout_note_slot is 39% of a spill-slot store (73 of ~187 runtime instructions), and 17.7 of it is element-shape bookkeeping on a NAMED-property store to an ordinary object

#10872

· proggeramlug opened

on Sep 21, 2026

perf: OBJ_FLAG_HAS_DESCRIPTORS is per-OBJECT, so one Object.defineProperty on one key takes every other key of that object off BOTH property ICs — 15.8x (126 -> 1991 instr/iteration, node 17.4 -> 20.8)

#10871

· proggeramlug opened

on Sep 21, 2026

rule 1 hole: Object.seal / Object.preventExtensions set OBJ_FLAG_SEALED / NO_EXTEND with no shape transition — safe today only by accident of what those flags forbid

#10870

· proggeramlug opened

on Sep 21, 2026

GC_OBJ_TYPED_LAYOUT_INTACT is not shape-determined: gc/layout/transfer.rs:180 re-sets it during a relocation with no shape change (blocks dropping the _reserved load from any property hit path)

#10869

· proggeramlug opened

on Sep 21, 2026

ShapeId exhaustion aborts the process after ~475 TypeScript transpiles (~2.26M ids minted per transpileModule, ~45 per AST node)

#10868

· proggeramlug opened

on Sep 21, 2026

perf: a read site whose hot key is in the overflow region can NEVER latch megamorphic — it stays armed forever and keeps paying way compares that can never hit (#7753 measured that at +37%)

#10863

· proggeramlug opened

on Sep 21, 2026

macOS: no appearance-adaptive (light/dark) colors — expose a dynamic color API

#10861

· steinybot opened

on Sep 21, 2026

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All issues

JSON.parse error message omits the position (line/column/offset) that other engines include

Object.prototype members are invisible to property reads and `in` unless the program names `Object.prototype` (`"toString" in {}` is false)

PERRY_DELETE_SHAPE_TRANSITION=0 is unsound now that the property ICs no longer test slots for TAG_HOLE — retire the kill switch (#10826 own note asked for it; the store tower now depends on it too)

A property miss is GEOMETRIC in prototype-chain depth (x2.1/level): 536,047 instructions for one absent read on an 8-deep chain

runtime: resizable ArrayBuffer unimplemented — `new ArrayBuffer(n, { maxByteLength })` ignores the options, `.resize()` is not a function

perf: layout_note_slot is 39% of a spill-slot store (73 of ~187 runtime instructions), and 17.7 of it is element-shape bookkeeping on a NAMED-property store to an ordinary object

perf: OBJ_FLAG_HAS_DESCRIPTORS is per-OBJECT, so one Object.defineProperty on one key takes every other key of that object off BOTH property ICs — 15.8x (126 -> 1991 instr/iteration, node 17.4 -> 20.8)

rule 1 hole: Object.seal / Object.preventExtensions set OBJ_FLAG_SEALED / NO_EXTEND with no shape transition — safe today only by accident of what those flags forbid

GC_OBJ_TYPED_LAYOUT_INTACT is not shape-determined: gc/layout/transfer.rs:180 re-sets it during a relocation with no shape change (blocks dropping the _reserved load from any property hit path)

ShapeId exhaustion aborts the process after ~475 TypeScript transpiles (~2.26M ids minted per transpileModule, ~45 per AST node)

perf: a read site whose hot key is in the overflow region can NEVER latch megamorphic — it stays armed forever and keeps paying way compares that can never hit (#7753 measured that at +37%)

macOS: no appearance-adaptive (light/dark) colors — expose a dynamic color API

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