chore: update dependency @swc/core to v1.15.21

[renovate]

This PR contains the following updates:

Package	Change	Age	Confidence
@swc/core (source)	1.15.18 → 1.15.21

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Release Notes

swc-project/swc (@​swc/core)

v1.15.21

Compare Source

Bug Fixes

• (cli) Honor externalHelpers=false in rust binary (#​11693) (1be052e)

• (cli) Skip mkdir when --out-file targets the current directory (#​11720) (f3f4e51)

• (es/decorators) Resolve 2022-03 issues #​9565/#​9078/#​9079 and add regressions (#​11698) (a025d2b)

• (es/fixer) Wrap new opt chain (#​11618) (fdcd184)

• (es/flow) Normalize module await bindings for Hermes parity (#​11703) (73d8761)

• (es/minifier) Fix compatibility for Wasm plugin (swc_ast_unknown) (#​11641) (abd0e45)

• (es/module) Preserve explicit index.js import path when baseUrl is set (#​11597) (830dbeb)

• (es/module) Avoid rewriting unknown relative extensions (#​11713) (ed09218)

• (es/regexp) Implement transform-named-capturing-groups-regex (#​11642) (f62bfa9)

• (es/types) Add new options types (#​11683) (62eeee1)

• (malloc) Fallback to system allocator on linux gnu s390x/powerpc (#​11606) (e103fac)

• Update lz4_flex to resolve RUSTSEC-2026-0041 (#​11701) (7528507)

Documentation

• (agents) Improve guidance (#​11626) (1cdfec9)

• (agents) Add AGENTS two-pass rules for es crates (#​11634) (12af4a1)

• Move parser design guidance into AGENTS.md (#​11600) (e6e91a3)

• Clarify workaround comment requirement in AGENTS (#​11700) (e2ad6f6)

Features

• (bindings) Add linux ppc64le and s390x support across npm bindings (#​11602) (357255d)

• (bindings) Enable flow strip support in @​swc/core (#​11696) (93da89a)

• (cli) Enable Flow strip support in swc_cli_impl (#​11705) (0ea9950)

• (dbg-swc) Add flow strip verification command (#​11706) (77b7854)

• (es) Add swc_es_codegen for swc_es_ast (#​11628) (c282d86)

• (es) Add 2-pass transformer and minifier crates (#​11632) (f70a4b7)

• (es) Add TypeScript + React transforms and tsc corpus tests (#​11635) (09a5d8d)

• (es/helpers) Prevent recursive instanceof helper transforms (#​11609) (cb755a3)

• (es/parser) Add with_capacity for Capturing (#​11679) (60df582)

• (es/parser) Add flow syntax mode and strip integration (#​11685) (015bbe8)

• (es/parser) Finish flow strip support for core syntax gaps (#​11689) (584a12f)

• (es/parser) Extend flow declare export strip compatibility (#​11691) (a8315aa)

• (es/parser) Support Flow declare export default interface strip path (#​11692) (588577c)

• (es/parser) Add Hermes Flow parity harness and fixes (#​11699) (918b6ac)

• (es/parser) Complete Hermes Flow stripping parity (#​11702) (f041f4c)

• (es/proposal) Add decorators 2023-11 support (#​11686) (e96eb6a)

• (es/react-compiler) Scaffold SWC port of Babel entrypoint (#​11687) (4a1d3ce)

• (es/react-compiler) Phase1 crate API baseline and fixture harness (#​11690) (31364dc)

• (es/react-compiler) Strict upstream parity finalization (crate-only, WIP) (#​11697) (a3994aa)

• (es/react-compiler) Advance strict upstream parity (#​11709) (9b3abe0)

• (es/react-compiler) Advance upstream fixture parity pipeline (#​11716) (33fe6f2)

• (es/semantics) Add scope analysis and statement-level cfg (#​11623) (86815b1)

• (es_parser) Complete parity suite with zero ignores (#​11615) (ee3fdd5)

• (es_parser) Complete internal parser wiring without ecma runtime dep (#​11622) (1c51891)

• (es_parser) Expand benchmark corpus (#​11633) (ff3adef)

• (react-compiler) Advance SWC upstream fixture parity (#​11718) (e8d1696)

• (react-compiler) Improve lint rename and gating parity (#​11721) (5f89ee7)

• (swc_es_parser) Enforce full parity suite and extend grammar surface (#​11611) (585f7d0)

• (swc_es_parser) Complete lossless modeling for with/TS module/decorators (#​11613) (59b1189)

• (swc_es_parser) Close parity gaps with full core/large fixture pass-fail parity (#​11614) (3085f52)

• Complete core parity parser coverage (#​11603) (18e0edc)

Performance

• (es/modules) Avoid export sort key clones (#​11669) (e74e17d)

• (es/parser) Reduce JSX identifier rescan allocations (#​11671) (f9214fe)

• (es/parser) Optimize underscore stripping in numeric literal hot path (#​11670) (874338b)

• (es/transformer) Remove O(n^2) statement mutation hotspots (#​11672) (bdc24b7)

• (es_parser) Byte-search lexer optimization pass (#​11616) (607f2db)

• (es_parser) Reduce lookahead and allocation overhead (#​11673) (becd9b0)

• (ts/fast-strip) Avoid token capture in default transform path (#​11668) (06aa0db)

Refactor

• (es/minifier) Use arguments data from scope (#​11604) (4738539)

Testing

• (es/flow) Add flow strip corpus correctness test (#​11694) (cd5ed81)

• (es/parser) Enforce full ecma fixture parity (#​11637) (0bf8a46)

• (es/parser) Expand flow strip fixture coverage (#​11695) (e231262)

• (es_parser) Add core snapshot suite (#​11617) (23c56fe)

• (es_parser) De-arenaize ecma_reuse fixture snapshots (#​11639) (aa6727a)

• (es_parser) Recover swc_es_parser benchmark coverage (#​11640) (0f24ee1)

• Expand swc_es_parser snapshot suites (ecma-style) (#​11621) (325170f)

• Move TS decorator fixtures out of proposal crate (#​11723) (e29d58c)

Ci

• Bump cargo-mono to 0.5.0 (#​11605) (7118713)

• Remove --no-verify flag from cargo mono publish (02eb5ec)

• Optimize cargo-test matrix with cargo mono changed (#​11681) (99e61c4)

• Bump cargo-mono to 0.5.3 (#​11722) (b5272af)

• Install zig for core ppc64le/s390x nightly cross builds (#​11725) (09c4be0)

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