fix(dayjs): arguments in seq exprs + computed Date-method dispatch (#5133)

CHANGELOG.md

@@ -1,3 +1,13 @@
+## v0.5.1171 — fix(dayjs): `arguments` in sequence exprs + computed Date-method dispatch (#5133)
+
+`compilePackages: dayjs` threw `ReferenceError: arguments is not defined`, and once that was resolved `.add()`/`.date(n)` silently no-op'd. Two distinct, general root causes:
+
+1. **`arguments` hidden inside a sequence expression.** Minified dayjs builds the wrapper as `O=function(t,e){...return n.date=t,n.args=arguments,new _(n)}` — the `arguments` reference lives inside a comma/sequence expression in the `return`. The synthetic-arguments pre-scan `expr_uses_arguments` (`crates/perry-hir/src/lower_decl/helpers.rs`) had no `Expr::Seq` arm, fell through its `_ => false` catch-all, so the enclosing function never synthesized its hidden raw-`arguments` param. Fix: descend into `Expr::Seq`, plus the other operand-bearing forms the catch-all skipped — `Await`, `Yield`, `OptChain`, computed `SuperProp`, `TaggedTpl`.
+
+2. **Computed/dynamic Date-method calls dropped to generic dispatch.** dayjs mutates dates via `this.$d[l]($)` (e.g. `date["setDate"](44)`). A `DateCell` is a NaN-boxed pointer but not an `ObjectHeader`; `js_native_call_method` special-cased only `toString` for date receivers, so every other computed/dynamic call fell through to generic object dispatch, returned `[object Object]` and dropped the mutation. Fix: route any method on a date receiver through `Date.prototype` (where all getter/setter/`toISOString`/`toJSON` thunks are installed and read `IMPLICIT_THIS`), with `this` bound to the cell.
+
+Known residual: a SIGSEGV in dayjs's month arithmetic (`.endOf('month')` / `.set('month', …)` — a number-as-pointer deref in `js_object_get_field_by_name`, unrelated to either fix here) is left for a follow-up.
+
 ## v0.5.1170 — fix(codegen): register rest/`arguments` metadata for renamed-export value wrappers (#5134)
 
 `.apply()`/`.call()` on a cross-module **default**-exported (or otherwise

CLAUDE.md

@@ -8,7 +8,7 @@ This file provides guidance to Claude Code (claude.ai/code) when working with co
 
 Perry is a native TypeScript compiler written in Rust that compiles TypeScript source code directly to native executables. It uses SWC for TypeScript parsing and LLVM for code generation.
 
-**Current Version:** 0.5.1170
+**Current Version:** 0.5.1171
 
 
 ## TypeScript Parity Status