AST primitives shrink to 16 bytes (
25e32c1)
Bun repacks core AST node types with #[repr(C, packed(4))], dropping Expr/Stmt/Binding from 24 to 16 bytes and reducing alignments across the hot path. The change also boxes a couple of rarely used fields to keep linker and AST data smaller, which should improve memory footprint and cache behavior.
fs.open now accepts integer-valued doubles (
e11be56)
fs.open/openSync/promises.open now accept numeric flags even when JSC boxes them as doubles, as long as they’re valid int32 integers. This fixes real wasm/Go compatibility issues where syscall/js passes values like 578 as a float, while still rejecting non-integer numbers.
node:v8 startupSnapshot.isBuildingSnapshot() returns false (4261a46)
Bun now matches Node by reporting false for startupSnapshot.isBuildingSnapshot() instead of throwing ERR_NOT_IMPLEMENTED. That unblocks modules like bson/mongodb that probe the API during import time.
fs compatibility jumps forward with Node v26.3.0 test ports (
dae2e87)
A large node:fs compatibility sweep ports upstream Node tests and fixes the behaviors they exposed: copy semantics, watcher delivery, glob, opendir, mkdtempDisposable, recursive rmdir end-of-life handling, and more. This is a broad correctness pass that materially improves Bun’s fs parity and raises coverage significantly.
Other misc changes
- Dependency/tooling and internal test fixture updates around the fs work
- Small AST/bundler/internal refactors to support the layout changes
- Added/updated tests for the v8 startup snapshot stub