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fix(native): Allow unmapped overflow owners in Linux cache ancestors (#12547)
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**Description:**
Linux user namespaces can report root-owned cache ancestors as owned by
the unmapped overflow UID. The native cache rejected these ancestors, so
both the user cache and `/tmp` fallback failed.
Treat an overflow owner like root only when `/proc/self/uid_map`
confirms that the UID is unmapped. Read proc information lazily, reuse
it within one path validation, and retain the existing checks if reading
or parsing fails. Directory mode, sticky-bit, symlink, and private cache
entry checks remain enforced.
Add mapping and permission fixtures plus a subprocess regression test
that loads a real native fixture from the default, custom, temporary,
and `/tmp` fallback caches, with and without a user namespace.
Validation of the code commit `7b3c6a3cd5` (the following commit adds
only a changeset):
- `cargo fmt --all` passed.
- `cargo clippy --all --all-targets -- -D warnings` passed on macOS.
Cargo profile and Clippy MSRV configuration warnings remain.
- `cargo test -p swc_native_addon` passed on macOS with the temporary
directory canonicalized, as in CI.
- `cargo test -p swc_native_addon` passed in Ubuntu 24.04 on Linux
arm64, both normally and under `unshare --user --map-current-user` as
UID/GID 1000. `SWC_TEST_REQUIRE_USERNS=1` ensured the namespace test did
not skip; the security opt-out was unset.
- `cargo clippy -p swc_native_addon --all-targets -- -D warnings` passed
on Linux.
- All crate tests passed with Rust 1.85.0 on Linux using an isolated
copy and the repository lockfile.
- The new namespace regression test failed against the unchanged
original implementation: `/` appeared as UID 65534 with mode 0755, and
both primary and fallback caches were rejected. It passed with this fix.
Docker used a read-only repository mount, a separate build/cache volume,
and `seccomp=unconfined` plus `apparmor=unconfined` to permit
unprivileged user namespaces.
**BREAKING CHANGE:**
None.
**Related issue (if exists):**
Closes #12542 fix(es/codegen): emit space after div if rhs starts with a regex (#12544)
**Description:**
With `minify: true`, a division whose right operand starts with a
regular expression literal is printed without a space, so the `/`
operator and the opening `/` of the regex become a `//` line comment:
```js
var f = (a) => a / /ab/.source.length;
console.log(f(4)); // 2
```
is printed as `var f=a=>a//ab/.source.length;console.log(f(4));` (with
`compress: false, mangle: false`; the defaults print `o=>o//ab/...`).
The rest of the line is commented out, so nothing is logged and there is
no error. In other positions the output fails to parse (`console.log(1 /
/x/.exec("x").length)` becomes `console.log(1//x/.exec("x").length)`).
With compress enabled the pattern can come from code that has no regex
after the `/`: `1 / new RegExp("ab").source.length` becomes
`1//ab/.source.length`. Reproduced with `@swc/core` 1.16.18 and
1.16.19-nightly-20261015.1, with and without compress and mangle.
A `/` followed by a leading comment already gets a space since #9631,
and `<` walks the emitted left edge of its right operand since #12523
(`starts_with_lt`). A `/` whose right operand starts with a regex
literal never got either check: for `/`, `emit_bin_expr_trailing` only
looks at `span.is_pure()` and leading comments.
This adds `starts_with_regex` next to `starts_with_lt` in
`util/token_boundaries.rs`. It follows the same emitted left edge (left
operands of binary, conditional and sequence expressions, member
objects, callees, optional chains, tagged template tags, postfix
updates, and TypeScript `!`, `as`, `satisfies`, `as const` and
instantiation expressions) and returns `true` when it reaches
`Lit::Regex`. Parentheses and prefix operators already separate the
tokens, so the walk stops there. The `/` arm of `emit_bin_expr_trailing`
now also emits the space when it returns `true`. Only outputs that
contain `//` at that boundary today change; `a /= /x/`, `a / (/x/, b)`,
`a / -/x/` and a regex on the left (`/x/ / 2`) print as before.
The check only runs in minify mode for the `/` operator, after the two
existing checks. It stops at the first node that is not on the left edge
(an identifier or a number returns on the first `match`) and does not
allocate.
**Tests:**
New fixtures in `tests/fixture/regex-division-boundary/`:
- `js/input.js` (`check_ast` and `exec`): a bare regex, flags, `/=/`,
member, call, computed member, optional chain, tagged template, `**`,
chained divisions, a regex on both sides, and a regex after `/` inside a
template, an object, an array, an arrow body, a `return` and a class
field. It also keeps the `/=`, parenthesized and unary cases, which were
already correct.
- `ts/input.ts` (`check_ast`): `/x/!` and `/x/<T>` on the right of `/`.
Both fail without the change (`generated code failed to parse` for `js`,
`generated code changed the AST` for `ts`; the minified output contains
`a//x/`) and pass with it. The new minified `js` output is the old one
with a space added at each of its 19 `/` + regex boundaries, and nothing
else.
- `cargo test -p swc_ecma_codegen --no-fail-fast`: 4213 passed, 0 failed
(4211 on `main` plus the 2 new fixtures).
- `cargo test -p swc_ecma_minifier --no-fail-fast`: 8023 passed, 0
failed, same as `main`, with no fixture or snapshot output changes.
- `crates/swc_ecma_minifier/scripts/exec.sh`: passes.
- `cargo clippy -p swc_ecma_codegen --all-targets -- -D warnings` and
`cargo fmt --all -- --check`: clean.
**Related issue (if exists):**
Closes #12530
---
Found with a differential fuzzer. Drafted with AI assistance. fix(es/fixer): preserve TypeScript operand grouping (#12539)
**Description:**
The fixer removes parentheses required by TypeScript around casts,
instantiations, and low-precedence cast inputs, producing invalid syntax
or changing the parsed expression. Preserve grouping across postfix
operations, updates, and binary operators—including `(f<T>)!`,
`(f<T>)++`, `(value as T).x`, `(value as T) & other`, `((a + b) as T) *
c`, and `(a | b) as T`.
Retain required innermost `ParenExpr` nodes in place and replace
`IndexMap::shift_remove` with indexed span records so nested parenthesis
restoration stays linear while preserving comment migration order.
**Related issue (if exists):**
- Follow-up to #12518 Latest Branches
+4%
fix/ts-namespace-enum-bindings +3%
kdy1/fix-native-cache-userns +6%
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