Bug Report
Current Behavior
TypeError: Property types[0] of UnionTypeAnnotation expected node to be of a type ["FlowType"] but instead got "TSTypeAnnotation"
at validate (/work/node_modules/@babel/types/lib/definitions/utils.js:128:13)
at validator (/work/node_modules/@babel/types/lib/definitions/utils.js:97:7)
at Object.validate (/work/node_modules/@babel/types/lib/definitions/utils.js:172:7)
at validate (/work/node_modules/@babel/types/lib/validators/validate.js:17:9)
at builder (/work/node_modules/@babel/types/lib/builders/builder.js:46:27)
at UnionTypeAnnotation (/work/node_modules/@babel/types/lib/builders/generated/index.js:733:31)
at Object.createUnionTypeAnnotation (/work/node_modules/@babel/types/lib/builders/flow/createUnionTypeAnnotation.js:20:47)
at NodePath.ConditionalExpression (/work/node_modules/@babel/traverse/lib/path/inference/inferers.js:124:14)
at NodePath._getTypeAnnotation (/work/node_modules/@babel/traverse/lib/path/inference/index.js:63:20)
at NodePath.getTypeAnnotation (/work/node_modules/@babel/traverse/lib/path/inference/index.js:29:19)
Input Code
https://github.com/azz/babel-typescript-union-bug
function bug() {
const x = 1 ? a() : b();
return [...x];
}
function a(): number[] {
return [];
}
function b(): number[] {
return [];
}Expected behavior/code
Not like this
Babel Configuration (.babelrc, package.json, cli command)
{
"plugins": ["@babel/plugin-transform-spread"],
"presets": ["@babel/preset-typescript"]
}Environment
- Babel version(s): 7.3.3
- Node/npm version: 6.5.0
- OS: macOS 10.14.2
- Monorepo: no
- How you are using Babel: cli
Possible Solution
The builder code for plugin-transform-spread is expecting a UnionTypeAnnotation instead of a TSUnionType in order to determine the type of x above, specifically in scope.toArray:
|
if (t.isIdentifier(node)) { |
|
const binding = this.getBinding(node.name); |
|
if (binding && binding.constant && binding.path.isGenericType("Array")) { |
|
return node; |
|
} |
|
} |
isGenericType ends up calling createUnionTypeAnnotation:
|
export function ConditionalExpression() { |
|
return t.createUnionTypeAnnotation([ |
|
this.get("consequent").getTypeAnnotation(), |
|
this.get("alternate").getTypeAnnotation(), |
|
]); |
|
} |
Which creates a UnionTypeAnnotation, which works for Flow, but not TypeScript.
Bug Report
Current Behavior
Input Code
https://github.com/azz/babel-typescript-union-bug
Expected behavior/code
Not like this
Babel Configuration (.babelrc, package.json, cli command)
Environment
Possible Solution
The builder code for
plugin-transform-spreadis expecting aUnionTypeAnnotationinstead of aTSUnionTypein order to determine the type ofxabove, specifically inscope.toArray:babel/packages/babel-traverse/src/scope/index.js
Lines 408 to 413 in 5bb1bb0
isGenericTypeends up callingcreateUnionTypeAnnotation:babel/packages/babel-traverse/src/path/inference/inferers.js
Lines 92 to 97 in 5bb1bb0
Which creates a
UnionTypeAnnotation, which works for Flow, but not TypeScript.