feature request: public the TransformationContext.addDiagnostic and read them in the compiler and transpileModule

[Jack-Works]

Search Terms

custom transformer diagnostic

Suggestion

mark the method addDiagnostic in TransformationContext as public and read the diagnostic result in the compiler

Use Cases

I'm writing a custom transformer. In some cases, the transform will fail but I don't want to throw an Error. I want to add my error to the diagnostics.

Examples

I have tried to call the addDiagnostic by as any

function createDiagnosticForNodeInSourceFile(
    ts: ts,
    sourceFile: SourceFile,
    node: Node,
    message: DiagnosticMessage,
    arg0?: string | number,
    arg1?: string | number,
    arg2?: string | number,
    arg3?: string | number,
): DiagnosticWithLocation | undefined {
    return (ts as any).createDiagnosticForNodeInSourceFile?.(sourceFile, node, message, arg0, arg1, arg2, arg3)
}
function appendDiagnosticMessageForNode(context: TransformationContext, diag: DiagnosticWithLocation | undefined) {
    if (!diag) return false
    const _context = internalTransformationContext(context)
    if (!_context.addDiagnostic) return false
    _context.addDiagnostic(diag)
    return true

    function internalTransformationContext(
        context: TransformationContext,
    ): TransformationContext & { addDiagnostic?(diag: DiagnosticWithLocation): void } {
        return context as any
    }
}

But that doesn't work. After digging into the source code, I found that it seems like the diagnostics only read in the dts generating.

Checklist

My suggestion meets these guidelines:

• This wouldn't be a breaking change in existing TypeScript/JavaScript code
• This wouldn't change the runtime behavior of existing JavaScript code
• This could be implemented without emitting different JS based on the types of the expressions
• This isn't a runtime feature (e.g. library functionality, non-ECMAScript syntax with JavaScript output, etc.)
• This feature would agree with the rest of TypeScript's Design Goals.

[RyanCavanaugh]

@rbuckton what are your thoughts?

[timocov]

I'd like to see this in public as well. In my transformer there are cases where I'm 100% sure that the error is possible and I need to notify about that somehow.

Any updates on this?

[timocov]

@rbuckton @RyanCavanaugh just a friendly ping (it seems that there is no answer since last Ryan's question, soooo...)

[timocov]

Probably after #54276 it would worth to re-visit this ticket? 😂 cc @jakebailey (sorry for pining)