[Bug] dispose error when using provideSignatureHelp when using model

[fabiojpoli]

Reproducible in vscode.dev or in VS Code Desktop?

• Not reproducible in vscode.dev or VS Code Desktop

Reproducible in the monaco editor playground?

• Not reproducible in the monaco editor playground

Monaco Editor Playground Code

var code = "function hello() {\n\talert('Hello world!');\n\tmyFn\n}";
var model = monaco.editor.createModel(code, 'javascript');

monaco.editor.create(document.getElementById('container'), {
	model: model
});

monaco.languages.registerSignatureHelpProvider('javascript', {
    signatureHelpTriggerCharacters: ['(', ','],
    provideSignatureHelp: function(model, position) {
      return {
         value: {
            activeSignature: 0,
            activeParameter: 0,
            signatures: [{
               label: 'method',
               documentation: 'this method does blah',
               parameters: [{
                  label: 'ParamInfo1',
                  documentation: 'this param does blah1'
               }, {
                  label: 'ParamInfo2',
                  documentation: 'this param does blah2'
               }]
            }]
         }
      };
   }
});

Reproduction Steps

Type (p1,p2 after myFn

Actual (Problematic) Behavior

Console error:
errors.ts:26 Uncaught Error: h.dispose is not a function

TypeError: h.dispose is not a function
at set value [as value] (lifecycle.ts:289:16)
at g. (parameterHintsModel.ts:221:35)
at Generator.next ()
at b (css.ts:80:37)
at errors.ts:26:12

Expected Behavior

No Console errors

Additional Context

Additional Question:
How to implement provideSignatureHelp correctly? There is no example using it and documentation doesn't match with return format.

I just need to see this when type "(" for first parameter:

And this for second parameter when type ",":

With highlight on each parameter. Besides the bug, could you please help me to implement this?

Thank you!

[tamayika]

I don't know the historical reason but you need to implement dispose. (while VSCode extension API does not)

var code = "function hello() {\n\talert('Hello world!');\n\tmyFn\n}";
var model = monaco.editor.createModel(code, 'javascript');

monaco.editor.create(document.getElementById('container'), {
	model: model
});

monaco.languages.registerSignatureHelpProvider('javascript', {
    signatureHelpTriggerCharacters: ['(', ','],
    provideSignatureHelp: function(model, position) {
      return {
         value: {
            activeSignature: 0,
            activeParameter: 0, // you need to change which parameter is typing
            signatures: [{
               label: 'blah(blah1, blah2)', // siagnature label must be entire function signature
               documentation: 'this method does blah',
               parameters: [{
                  label: 'blah1', // parameter label must be partial of signature label
                  documentation: 'this param does blah1',
               }, {
                  label: 'blah2', // parameter label must be partial of signature label
                  documentation: 'this param does blah2'
               }]
            }]
         },
         dispose: () => {},
      };
   }
});

[fabiojpoli]

Thank you @tamayika!

The hint is not closing automatically after type ")". How could I do that manually to fix this problem? Thank you!

[fabiojpoli]

For now my workaround is:

provideSignatureHelp: function(model, position) {
   var me = this,
      currentChar = model.getLineContent(position.lineNumber)[position.column - 2];

   // if is typing ")" just close the parameters hint
   if (currentChar === ')') {
      return {
         dispose: () => {},
         value: {}
      };
   }
   ...
}

[tamayika]

Yes, you need to return empty result when out of call expression.
Generally, you need AST parser because you can not determine current text is comment or string literal or call expression.
With AST, you can know argument index and out of call expression.