fix(es/minifier): preserve non-canonical arguments access - #12052
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Donny/강동윤 (kdy1)
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Jul 22, 2026
**Description:** ECMAScript bitwise NOT first applies `ToInt32`, including wraparound for out-of-range numbers. Folding with direct Rust casts does not reproduce those conversions at the boundaries. This PR delegates numeric bitwise NOT folding to the existing `JsNumber` implementation and adds coverage for boundary, wraparound, and very large values. The simplifier now uses the same number semantics as the rest of the optimizer. **Related issue (if exists):** - Close: #12062 --- - #12043 - #12047 - #12050 - #12048 - #12051 - #12052 - #12053 - #12054 - #12055 - #12056 - #12057 - **#12058** (current) - #12049 - #12059 - #12060
Donny/강동윤 (kdy1)
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Jul 22, 2026
**Description:** Several property-key optimizations rely on Rust number formatting or eagerly parse strings as numbers. This can merge distinct ECMAScript keys, including `Infinity` and `inf`, `-0` and `0`, or `"01"` and `"1"`. This PR introduces shared canonical-index parsing and ECMAScript number-to-string conversion, then uses them across property-key transforms, literal folding, and TypeScript name extraction. Each path now preserves property-key identity before optimizing it. **Related issue (if exists):** - Close: #12061 --- - #12043 - #12047 - **#12050** (current) - #12048 - #12051 - #12052 - #12053 - #12054 - #12055 - #12056 - #12057 - #12058 - #12049 - #12059 - #12060
Donny/강동윤 (kdy1)
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…12049) **Description:** Enum evaluation currently rebuilds computed `NaN` and infinity values as identifiers. That turns numeric constants into apparent references and loses number-literal semantics as values move through the TypeScript transform and fast-DTS evaluators. This PR keeps computed enum numbers as `Number` literals in both paths, applies JavaScript number stringification when names are required, and corrects modulo evaluation for non-finite operands. **Related issue (if exists):** - #12043 - #12047 - #12050 - #12048 - #12051 - #12052 - #12053 - #12054 - #12055 - #12056 - #12057 - #12058 - **#12049** (current) - #12059 - #12060 Co-authored-by: Donny/강동윤 <kdy.1997.dev@gmail.com>
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Donny/강동윤 (kdy1)
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Jul 23, 2026
**Description:** `Number#toString(radix)` folding currently converts integer values through `u128`. Unsafe integers can already have rounded representations, so this conversion can produce digits that do not match JavaScript for non-power-of-two radices. This PR restricts radix folding to safe integers, with a separate exact path for supported power-of-two radices below the `u128` bound. Values outside those limits remain for runtime evaluation. **Related issue (if exists):** - #12043 - #12047 - #12050 - #12048 - #12051 - #12052 - #12053 - #12054 - #12055 - #12056 - **#12057** (current) - #12058 - #12049 - #12059 - #12060
Donny/강동윤 (kdy1)
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Jul 23, 2026
**Description:** `Array(length)` throws a `RangeError` when the length is fractional or otherwise invalid. Folding every small numeric length into an array literal suppresses that observable exception. This PR requires candidate lengths to be integers before applying the literal-folding optimization and adds runtime coverage for invalid lengths. Valid small arrays are still folded as before. **Related issue (if exists):** - #12043 - #12047 - #12050 - #12048 - #12051 - #12052 - #12053 - #12054 - #12055 - **#12056** (current) - #12057 - #12058 - #12049 - #12059 - #12060
Donny/강동윤 (kdy1)
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Jul 23, 2026
Donny/강동윤 (kdy1)
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Jul 23, 2026
**Description:** `String.fromCharCode` applies ECMAScript `ToUint16` to every argument. The current floor-and-cast folding path does not match that behavior for negative, wrapping, or non-finite inputs. This PR adds `JsNumber::to_uint16` and uses it before folding ASCII `String.fromCharCode` results. Boundary coverage keeps the optimization limited to values whose output can be produced safely. **Related issue (if exists):** - #12043 - #12047 - #12050 - #12048 - #12051 - #12052 - #12053 - #12054 - **#12055** (current) - #12056 - #12057 - #12058 - #12049 - #12059 - #12060
Donny/강동윤 (kdy1)
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Jul 23, 2026
**Description:** Enum template evaluation currently reads raw template source and converts atoms lossily. Escapes, interpolation, and lone surrogates can therefore diverge from the cooked JavaScript string used at runtime. This PR evaluates template quasis and static template member keys from cooked WTF-8 values in both the transform and fast-DTS paths. Lookup and concatenation retain lone surrogates without changing the surrounding enum evaluation model. **Related issue (if exists):** - #12043 - #12047 - #12050 - #12048 - #12051 - #12052 - #12053 - #12054 - #12055 - #12056 - #12057 - #12058 - #12049 - **#12059** (current) - #12060
Donny/강동윤 (kdy1)
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Jul 23, 2026
**Description:** JavaScript string property indexing uses UTF-16 code units. Existing constant folding checked string-literal indices against WTF-8 byte length, which can treat out-of-bounds indices as valid for non-ASCII BMP characters, astral characters, and lone surrogates. In the expression simplifier, that mismatch could also reach an `unreachable!` branch. This PR validates and reads string-literal indices using UTF-16 code units in both the minifier and expression simplifier. It preserves the WTF-8 byte-length check as a fast upper-bound rejection, folds valid indices to the correct code unit, and handles UTF-16 out-of-bounds indices according to each pass's existing semantics. Coverage includes BMP non-ASCII characters, astral surrogate pairs, and lone surrogates. The change was verified with: - `cargo test -p swc_ecma_minifier -p swc_ecma_transforms_optimization` - `(cd crates/swc_ecma_minifier && ./scripts/exec.sh)` - `cargo fmt --all` - `cargo clippy --all --all-targets -- -D warnings` **Related issue (if exists):** - #12043 - #12047 - #12050 - #12048 - #12051 - #12052 - #12053 - **#12054** (current) - #12055 - #12056 - #12057 - #12058 - #12049 - #12059 - #12060
Donny/강동윤 (kdy1)
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Jul 24, 2026
**Description:** The optimizer currently represents `NaN` and infinities in several forms, including identifiers, divisions, and numeric literals. As these forms move through multiple optimization passes, they can be folded inconsistently and acquire incorrect truthiness or stringification. This PR canonicalizes non-finite optimization results as raw-free `Lit::Num` values. Minifier and simplifier helpers then preserve ECMAScript behavior for these numbers, while codegen remains responsible for choosing valid output syntax. **Related issue (if exists):** - #12043 - #12047 - #12050 - **#12048** (current) - #12051 - #12052 - #12053 - #12054 - #12055 - #12056 - #12057 - #12058 - #12049 - #12059 - #12060
Donny/강동윤 (kdy1)
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Jul 28, 2026
**Description:** The JSON parse optimization had a number fast path that cast through `i64`. That path could be unsafe for out-of-range values and for `-0`, changing observable results. This PR keeps the optimization but only uses the `i64` path when safe: when the number is an integer within `i64` range and does not alter the zero sign. Other finite numbers are serialized via `serde_json::Number::from_f64`, and non-finite handling is updated so `NaN` is rejected while `±Infinity` is emitted as `±2e308`. **Related issue (if exists):** - #12043 - #12047 - #12050 - #12048 - **#12051** (current) - #12052 - #12053 - #12054 - #12055 - #12056 - #12057 - #12058 - #12049 - #12059 - #12060
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Description:
Computed
argumentsproperties are currently parsed or cast directly as numeric indices. Non-canonical names and invalid indices can therefore be mistaken for parameter positions and replaced incorrectly.This PR resolves
argumentsslots through the shared canonical-index parser and ECMAScript number-to-string conversion before substituting parameters. An access is optimized only when its property denotes the same canonical argument index.Related issue (if exists):
argumentsproperty names as parameter indices #12066