fix(tsconfig): apply later-wins semantics for extends array#1156
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Per TypeScript spec, when `extends` is an array, later configurations override earlier ones. typescript-go implements this by accumulating into a result that each base overwrites in turn (`applyExtendedConfig` + `mergeCompilerOptions`). oxc-resolver's `extend_tsconfig` only fills `None` fields, so iterating forward made the first base set a value, blocking later bases from overriding it — first-wins instead of later-wins. Fix: iterate `extended_tsconfig_paths` in reverse in both extend sites (`load_tsconfig` and the project-references `extend_tsconfig`). The last base now sets fields first; earlier bases see them set and skip; the child's own explicit fields (set before any extend) still win because they're populated before either loop runs. Removes the `#[ignore]` on `tsconfig_lookup::extends_array_last_wins` which now passes. Existing `extends-multiple` still passes because that test resolves via `baseUrl` fall-through, not via the order of inherited `paths`.
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## 🤖 New release * `oxc_resolver`: 11.19.1 -> 11.19.2 * `oxc_resolver_napi`: 11.19.1 -> 11.19.2 <details><summary><i><b>Changelog</b></i></summary><p> ## `oxc_resolver` <blockquote> ## [11.19.2](v11.19.1...v11.19.2) - 2026-05-25 ### <!-- 1 -->🐛 Bug Fixes - *(tsconfig)* apply later-wins semantics for extends array ([#1156](#1156)) (by @Boshen) - *(tsconfig)* walk past a tsconfig that doesn't claim the file ([#1154](#1154)) (by @Boshen) - *(tsconfig)* let project references take priority over their parent ([#1151](#1151)) (by @Boshen) - *(tsconfig)* resolve `rootDirs` against the config that declared them ([#1150](#1150)) (by @Boshen) - *(tsconfig)* resolve `baseUrl` / `paths` against the canonical tsconfig path ([#1148](#1148)) (by @Boshen) - strip query fragments when calling `find_tsconfig` ([#1147](#1147)) (by @Boshen) - avoid panic in resolve_file for parentless paths ([#1053](#1053)) (by @Boshen) - *(dts)* strip ./ prefix from package entry when matching typesVersions ([#1051](#1051)) (by @Boshen) - *(dts)* expand Declaration to TypeScript|Declaration for package entry resolution ([#1050](#1050)) (by @Boshen) - *(dts)* prefer declaration extensions over JS in exports-resolved paths ([#1047](#1047)) (by @Boshen) - avoid wasm/wasi dead-code lint in NodePath ([#1043](#1043)) (by @Boshen) - *(napi)* replace panics with error returns to prevent WASM traps ([#1055](#1055)) (by @Boshen) ### <!-- 2 -->🚜 Refactor - remove clear_cache test that dynamically creates fixtures (by @Boshen) - move resolve and misc fixtures into fixtures/integration (by @Boshen) - replace ignored doctest with link to example (by @Boshen) - consolidate fixture directories for better test file mapping (by @Boshen) - replace `url` crate with `percent-encoding` ([#1065](#1065)) (by @Boshen) ### <!-- 4 -->⚡ Performance - *(cache)* pack CachedPathImpl::meta into a CachedMeta byte ([#1144](#1144)) (by @Boshen) - *(cache)* store canonical path as Box<Path> instead of PathBuf ([#1143](#1143)) (by @Boshen) - *(alias)* fast-reject alias entries by cached first byte ([#1142](#1142)) (by @Boshen) ### <!-- 6 -->🧪 Testing - *(tsconfig)* port lookup scenarios from typescript-go ([#1155](#1155)) (by @Boshen) - add 28 tests to improve coverage (92% → 93%) ([#1082](#1082)) (by @Boshen) ### Contributors * @Boshen * @renovate[bot] </blockquote> </p></details> --- This PR was generated with [release-plz](https://github.com/release-plz/release-plz/). Co-authored-by: oxc-guard[bot] <276638029+oxc-guard[bot]@users.noreply.github.com>
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Summary
Per TypeScript spec, when
extendsis an array, later configurations override earlier ones. typescript-go implements this by accumulating into a result that each base overwrites in turn (applyExtendedConfig→mergeCompilerOptions).oxc-resolver's
extend_tsconfigonly fillsNonefields, so iterating forward made the first base set a value, blocking later bases from overriding it — first-wins instead of later-wins.Fix: iterate
extended_tsconfig_pathsin reverse in both extend sites (load_tsconfigand the project-referencesextend_tsconfig). The last base now sets fields first; earlier bases see them set and skip; the child's own explicit fields (set before any extend) still win because they're populated before either loop runs.Removes the
#[ignore]ontsconfig_lookup::extends_array_last_wins(added in #1155) which now passes. The existingextends-multipletest still passes because it resolves viabaseUrlfall-through, not via the order of inheritedpaths.🤖 Generated with Claude Code