💻

• Would you like to work on a fix?

How are you using Babel?

Programmatic API (babel.transform, babel.parse)

Input code

See REPL: https://runkit.com/alexandre-cai/60a2ae9feaab4400130133c8

transform(`
  type Test = 1 | -1;
`, {
  parserOpts: {
    plugins: ["typescript"],
  },
  plugins: [
    ({ types: t }) => ({
      visitor: {
        TSLiteralType(path) {
          path.node = t.tsLiteralType(path.node.literal)
        }
      }
    }),
  ],
})

Configuration file name

No response

Configuration

No response

Current and expected behavior

Babel currently accepts UnaryExpression while parsing TSLiteralType, but can’t generate one. Output:

TypeError: unknown: Property literal of TSLiteralType expected node to be of a type 
["NumericLiteral","StringLiteral","BooleanLiteral","BigIntLiteral"] but instead got "UnaryExpression"

Environment

• @babel/core: 7.14.2

Possible solution

https://github.com/babel/babel/blob/main/packages/babel-types/src/definitions/typescript.ts#L342
Add UnaryExpression.

Additional context

No response