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fix(codegen): parenthesize TS-cast assignment targets#23112

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codegen-ts-cast-assignment-target-parens
Jun 8, 2026
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fix(codegen): parenthesize TS-cast assignment targets#23112
graphite-app[bot] merged 1 commit into
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codegen-ts-cast-assignment-target-parens

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@Boshen

@Boshen Boshen commented Jun 8, 2026

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A TypeScript wrapper used as an assignment target — (x as T) = v, (x satisfies T) = v, (<T>x) = v — must keep its parentheses, otherwise codegen emits invalid output such as x as T = v.

AssignmentTarget's codegen printed the simple target at Precedence::Comma (1), too low to make the wrapper parenthesize itself: TSAsExpression / TSSatisfiesExpression wrap at >= Compare (13) and TSTypeAssertion at >= Prefix (18). So the parentheses were dropped and the output no longer re-parsed.

It now passes the minimal precedence that forces each wrapper to wrap — Compare for as / satisfies, Prefix for the angle-bracket type assertion.

Surfaced while round-tripping code through oxc_react_compiler, but it is a general codegen bug affecting any TS-cast assignment target.

🤖 Generated with Claude Code

@github-actions github-actions Bot added the A-codegen Area - Code Generation label Jun 8, 2026
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codspeed-hq Bot commented Jun 8, 2026

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Merging this PR will not alter performance

✅ 57 untouched benchmarks
⏩ 9 skipped benchmarks1


Comparing codegen-ts-cast-assignment-target-parens (a8ea23c) with main (8eb5507)

Open in CodSpeed

Footnotes

  1. 9 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports.

@Boshen Boshen added the 0-merge Merge with Graphite Merge Queue label Jun 8, 2026

Boshen commented Jun 8, 2026

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A TypeScript wrapper used as an assignment target — `(x as T) = v`, `(x satisfies T) = v`, `(<T>x) = v` — must keep its parentheses, otherwise codegen emits invalid output such as `x as T = v`.

`AssignmentTarget`'s codegen printed the simple target at `Precedence::Comma` (1), too low to make the wrapper parenthesize itself: `TSAsExpression` / `TSSatisfiesExpression` wrap at `>= Compare` (13) and `TSTypeAssertion` at `>= Prefix` (18). So the parentheses were dropped and the output no longer re-parsed.

It now passes the minimal precedence that forces each wrapper to wrap — `Compare` for `as` / `satisfies`, `Prefix` for the angle-bracket type assertion.

Surfaced while round-tripping code through `oxc_react_compiler`, but it is a general codegen bug affecting any TS-cast assignment target.

🤖 Generated with [Claude Code](https://claude.com/claude-code)
@graphite-app graphite-app Bot force-pushed the codegen-ts-cast-assignment-target-parens branch from a8ea23c to 556acdc Compare June 8, 2026 09:22
@graphite-app graphite-app Bot merged commit 556acdc into main Jun 8, 2026
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@graphite-app graphite-app Bot removed the 0-merge Merge with Graphite Merge Queue label Jun 8, 2026
@graphite-app graphite-app Bot deleted the codegen-ts-cast-assignment-target-parens branch June 8, 2026 09:26
Boshen added a commit that referenced this pull request Jun 8, 2026
### 💥 BREAKING CHANGES

- ee4dc73 ast: [**BREAKING**] Add `#[non_exhaustive]` to AST nodes
(#23046) (overlookmotel)
- 4c35362 ast: [**BREAKING**] Add
`AstBuilder::template_element_escape_raw` and
`template_element_escape_raw_with_lone_surrogates` methods (#23047)
(overlookmotel)

### 🚀 Features

- b846ab2 react_compiler: Integrate the Rust port of the React Compiler
(#22942) (Boshen)
- 5b8dd68 parser: Report TS1255 for invalid class definite assertions
(#22917) (camc314)
- 85efabf semantic: Make building the class table optional, off by
default (#22862) (Boshen)

### 🐛 Bug Fixes

- 556acdc codegen: Parenthesize TS-cast assignment targets (#23112)
(Boshen)
- 37169ff codegen: Don't emit space between postfix `--` and `>` when
minifying (#23036) (Boshen)
- a4b1bf7 codegen: Drop redundant whitespace in minified TypeScript
output (#23038) (Boshen)
- cf53285 parser: Report reserved type-declaration names in the parser
(#23035) (Boshen)
- 4e44969 ast: Fix UB in `escape_template_element_raw` (#23052)
(overlookmotel)
- c543154 parser: Report comma operator in JSX expression in the parser
(#23030) (Boshen)
- 325c94f codegen: Tighten conditional-type and constructor-type
whitespace when minifying (#23033) (Boshen)
- 95dd3a2 parser: Report `import type` alias to a non-external reference
in the parser (#23032) (Boshen)
- 90180b8 codegen: Drop space after `:` in function return type when
minifying (#23028) (Boshen)
- 6da876e parser: Report `abstract` private class field in the parser
(#23029) (Boshen)
- 28467ce codegen: Don't emit space before a postfix update operand when
minifying (#23027) (Boshen)
- cb29926 codegen: Drop redundant space after `export default` when
minifying (#23024) (Boshen)
- 62965ae codegen: Drop redundant space after `else` when minifying
(#23025) (Boshen)
- 989230a parser: Report compound assignment to non-simple target in the
parser (#23022) (Boshen)
- 06f367c parser: Report `super.#field` private access in the parser
(#23014) (Boshen)
- 184edef codegen: Print space before `const`/`declare` enum modifier
(#23013) (Boshen)
- 4d722e0 parser: Report duplicate switch `default` clause in the parser
(#23012) (Boshen)
- 597ed85 codegen: Parenthesize `let`/`async` for-of head target
(#23008) (Boshen)
- 8b631bf codegen: Remove stray space before mapped type value colon
(#23010) (Boshen)
- c08407e codegen: Don't over-parenthesize `in` inside an arrow in a
for-init (#23009) (Boshen)
- 600cd6f codegen: Parenthesize lower-precedence
`TSInstantiationExpression` operand (#23007) (Boshen)
- 187e1a5 codegen: Don't leak space after comment-only JSX expression
container (#23006) (Boshen)
- 294c473 codegen: Don't over-parenthesize `TSTypeAssertion` operand
(#23004) (Boshen)
- 786d96f codegen: Give `TSTypeAssertion` unary precedence (#23002)
(Boshen)
- 1295882 parser: Report `new.target` and `import.meta` syntax errors in
the parser (#23003) (Boshen)
- d727b6b codegen: Parenthesize `await` expression as base of `**`
(#23001) (Boshen)
- 67dfa08 codegen: Keep parentheses around `new` callees containing a
call (#22997) (Boshen)
- 17e7cf3 parser: Disallow unerasable `as`/`satisfies` assertions
(#22986) (Boshen)
- beb46d3 parser: Commit to module goal on decorated exports (#22941)
(Boshen)
- 49e63f7 isolated-declarations: Require annotations for satisfies
initializers (#22898) (camc314)
- 8c93601 isolated-declarations: Allow unknown enum initializer in
non-const enum (#22900) (camc314)

### ⚡ Performance

- 7d89909 parser: Peek instead of lookahead for yield disambiguation
(#23071) (Boshen)
- bf872f0 parser: Skip arrow lookahead for a parenthesized literal
(#23070) (Boshen)
- d19fc54 parser: Guard type-argument speculation behind an angle-token
check (#23069) (Boshen)
- 8eb5507 parser: Skip redundant member-rest re-scan on call entry
(#23068) (Boshen)
- 883dfc1 parser: Skip parse_call_expression_rest when no call follows
(#23063) (Boshen)
- b171153 parser: Peek before the await-using lookahead (#23059)
(Boshen)
- 56f21bd parser: Use peek_token for the TS `asserts` type predicate
(#23058) (Boshen)
- 68805ac parser: Use peek_token instead of checkpoint/rewind for
single-token decisions (#23056) (Boshen)
- 1f9d8eb ast: `AstBuilder::template_element_escape_raw` avoid
allocation if no escape required (#23053) (overlookmotel)
- 502b04d semantic: Move cold function redeclaration handling into
`#[cold]` function (#22973) (overlookmotel)

### 📚 Documentation

- 275d318 napi/minifier: Point `target` to oxc docs (#23102) (camc314)

Co-authored-by: Boshen <1430279+Boshen@users.noreply.github.com>
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