Ts-morph: Adding type to param of non-parenthesized arrow function throws error

[gregjacobs]

Now this one might be a bit of a challenge...

I tried to add a type annotation to a parameter of an arrow function where the arrow's single parameter is not surrounded by parenthesis:

myArg => console.log( myArg );

Here's my reproduction of the error:

import Project, { ArrowFunction, SyntaxKind } from 'ts-simple-ast';

const project = new Project();
const sourceFile = project.createSourceFile( 'my-file.ts', `
    myArg => console.log( myArg );
` );


const arrowFunction = sourceFile
    .getDescendantsOfKind( SyntaxKind.ArrowFunction )[ 0 ] as ArrowFunction;

const arrowParam = arrowFunction.getParameters()[ 0 ];
arrowParam.setType( 'any' );

Which results in:

Error: Error replacing tree! Perhaps a syntax error was inserted (Current: ExpressionStatement -- New: LabeledStatement).
-- Details --
Path: my-file.ts
Text: "\n\tmyArg: any => console.log( myArg );\n"

I think it may be ending up with this output text after the replacement:

myArg: any => console.log( myArg );

Rather than:

(myArg: any) => console.log( myArg );

[dsherret]

Nice, I like this bug! It shows the benefit of the library and how it can abstract away these problems. I'll fix this tomorrow evening.

[gregjacobs]

Hehe, sounds good! And yes, that is a good call and a huge benefit of ts-simple-ast!

Thanks for taking a look :)

[dsherret]

Hey @gregjacobs, this is fixed in 12.7.2. Also fixed for setInitializer and setHasQuestionToken.

Let me know if you run into or think of any more scenarios. Thanks!

[gregjacobs]

Very nice, thanks man! Nice implementation too :smile:

Appreciate it!