Nested arrays cause off-by-one error in generated sourcemaps #8066
Description
Describe the bug
When SWC transforms a nested array, the resulting sourcemap has an off-by-one error where the mapping for the end of one of the arrays points to an invalid location in the source.
I validated this by taking the input code below and running it through this code:
import { transform } from '@swc/core';
import fs from 'node:fs';
async function main() {
const result = await transform(fs.readFileSync('./src/index.js', 'utf8'), {
sourceMaps: true,
});
fs.writeFileSync('./dist/index.js', result.code, 'utf8');
fs.writeFileSync('./dist/index.js.map', result.map + "\n//# sourceMappingURL=index.js.map",'utf8');
}
main().catch(e => {
process.exitCode = 1;
console.error(e);
})
.. and then trying to load the resulting output with source-map-explorer which fails with:
Your source map refers to generated column 7 on line 2, but the source only contains 6 column(s) on that line.
Check that you are using the correct source map.
See also the attached Source Map Visualiser link in the repro.
Input code
var a = [[]];Config
n/aPlayground link (or link to the minimal reproduction)
SWC Info output
Operating System:
Platform: darwin
Arch: arm64
Machine Type: arm64
Version: Darwin Kernel Version 22.6.0: Fri Sep 15 13:41:28 PDT 2023; root:xnu-8796.141.3.700.8~1/RELEASE_ARM64_T6000
CPU: (10 cores)
Models: Apple M1 Pro
Binaries:
Node: 18.18.0
npm: 9.8.1
Yarn: 1.22.19
pnpm: N/A
Relevant Packages:
@swc/core: 1.3.91
@swc/helpers: 0.5.2
@swc/types: 0.1.5
SWC Config:
output: N/A
.swcrc path: N/A
Next.js info:
output: N/A
Expected behavior
The sourcemap will be valid.
Actual behavior
The sourcemap is invalid, the second closing paren is mapped past the end of the line:
Version
1.3.91