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fix(es/minifier): Preserve `cooked` when concatenating template literals (#11939)
**Description:**
When `compress` folds `a + b` and both sides are template literals,
`concat_tpl` merges them into one template literal. Merging the boundary
quasis — the last quasi of the left template with the first quasi of the
right — updates `raw` but not `cooked`, leaving the merged quasi with
`raw` and `cooked` out of sync. Downstream passes (`eval_tpl_as_str`,
`eval_nested_tpl`, `compress_tpl`) evaluate the template to a string via
`cooked`, so the text after the left template's last interpolation is
silently dropped. The result is wrong but not a syntax error, so it
ships.
Example (`@swc/core` 1.15.41):
```js
const { minifySync } = require("@swc/core");
const src = "const html = `<b>${1}</b>` + `<i>${2}</i>`;";
console.log(minifySync(src, { compress: true }).code);
```
Output — the closing `</b>` is dropped:
```js
const html = "<b>1<i>2</i>"; // expected: "<b>1</b><i>2</i>"
```
So at runtime the original yields `<b>1</b><i>2</i>`, but the minified
code yields `<b>1<i>2</i>`.
The dropped text is whatever follows the **left** template's last
interpolation:
| Source | Expected | Minified |
| --- | --- | --- |
| `` `<b>${1}</b>` + `<i>${2}</i>` `` | `<b>1</b><i>2</i>` |
`<b>1<i>2</i>` |
| `` `width:${1}px;` + `height:${2}px;` `` | `width:1px;height:2px;` |
`width:1height:2px;` |
| `` `(${1})` + ` (${2})` `` | `(1) (2)` | `(1 (2)` |
Smallest reproduction:
```js
require("@swc/core").minifySync("x = `a${0}]` + `${0}b`", { compress: true }).code
// actual: x="a00b";
// expected: x="a0]0b";
```
The trigger requires **both** template literals to contain an
interpolation (`` `a${1}b` + `plain` `` is unaffected, since the right
side has none).
The sibling branches `Tpl + Str` and `Str + Tpl` already merge `cooked`;
only the `Tpl + Tpl` branch was missing it.
**Fix:** in the `Tpl + Tpl` branch of `concat_tpl`, merge `cooked` the
same way `raw` is merged, falling back to `None` if either side's
`cooked` is `None` (an invalid escape sequence). Added an exec
regression test that runs the original and the minified code and
compares the output. `cargo test -p swc_ecma_minifier` passes (lib: 49,
exec: 481, 0 failures).
**Related issue (if exists):**
None found — this appears to be unreported. It also surfaces through
bundlers that wrap swc's JS minifier (e.g. rspack / rsbuild). Latest Branches
0%
wbinnssmith:wbinnssmith/typed-this-react-compiler 0%
pkasarda:fix-es-minifier-concat-tpl-cooked 0%
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