[Bug]: TypeScript compilation throws error on correct program (type inference on array spread syntax?) #15380
Description
💻
- Would you like to work on a fix?
How are you using Babel?
@babel/cli
Input code
const foo = () => {
const bar = 0 ? mkList() : [];
return [...bar];
};
function mkList(): any[] {
return [];
}
export default {};This REPL session also showcases the issue.
Configuration file name
babel.config.json
Configuration
{
"presets": [
"@babel/preset-env",
"@babel/preset-typescript"
]
}Current and expected behavior
Current behavior: compilation fails with the following log:
$ /tmp/babel/node_modules/.bin/babel src --extensions .ts -d build
TypeError: /tmp/babel/src/index.ts: Property types[1] of TSUnionType expected node to be of a type ["TSType"] but instead got "GenericTypeAnnotation"
at validate (/tmp/babel/node_modules/@babel/types/lib/definitions/utils.js:112:11)
at validator (/tmp/babel/node_modules/@babel/types/lib/definitions/utils.js:88:7)
at Object.validate (/tmp/babel/node_modules/@babel/types/lib/definitions/utils.js:188:7)
at validateField (/tmp/babel/node_modules/@babel/types/lib/validators/validate.js:21:9)
at validate (/tmp/babel/node_modules/@babel/types/lib/validators/validate.js:15:3)
at validateNode (/tmp/babel/node_modules/@babel/types/lib/builders/validateNode.js:12:27)
at tsUnionType (/tmp/babel/node_modules/@babel/types/lib/builders/generated/index.js:1757:36)
at createTSUnionType (/tmp/babel/node_modules/@babel/types/lib/builders/typescript/createTSUnionType.js:18:39)
at createUnionType (/tmp/babel/node_modules/@babel/traverse/lib/path/inference/util.js:24:16)
at NodePath.ConditionalExpression (/tmp/babel/node_modules/@babel/traverse/lib/path/inference/inferers.js:118:36) {
code: 'BABEL_TRANSFORM_ERROR'
}
error Command failed with exit code 1.
Moving the function definition for mkList to the top of the file fixes the issue. So does adding a type assertion on line 4: return [...(bar as typeof bar)];.
Setting targets to "defaults" in the config also fixes the issue.
Environment
System:
OS: macOS 12.5.1
Binaries:
Node: 16.17.0 - ~/.nvm/versions/node/v16.17.0/bin/node
Yarn: 1.22.19 - ~/.nvm/versions/node/v16.17.0/bin/yarn
npm: 8.15.0 - ~/.nvm/versions/node/v16.17.0/bin/npm
npmPackages:
@babel/cli: 7.20.7 => 7.20.7
@babel/core: 7.20.12 => 7.20.12
@babel/preset-env: 7.20.2 => 7.20.2
@babel/preset-typescript: 7.18.6 => 7.18.6
Possible solution
No response
Additional context
This appears to be a regression between 7.17 and 7.18. See this REPL session, where I just changed the version to 7.17.
In the CLI, I can make the compilation succeed with the following package.json file for Yarn:
{
"devDependencies": {
"@babel/cli": "~7.17.0",
"@babel/core": "~7.17.0",
"@babel/preset-env": "~7.17.0",
"@babel/preset-typescript": "~7.17.0",
"typescript": "4.9.4"
},
"resolutions": {
"@babel/types": "~7.17.0",
"@babel/generator": "~7.17.0",
"@babel/traverse": "~7.17.0"
}
}