Signature help not select correct overload for partially completed function

[mjbvz]

From microsoft/vscode#80570

TypeScript Version: 3.7.0-dev.20190907

Search Terms:

• SignatureHelp
• parameter hints

Code
For the code

declare function addEventHandler(event: "onPlayerJoin", x: number): void;
declare function addEventHandler(event: "onPlayerQuit", y: string): void;

addEventHandler('onPlayerQuit')

1. Trigger signature help after the closing ' in the call to addEventHandler

Expected behavior:
Signature help for the second overload is returned

Actual behavior:
Signature help for both overloads is returned. We end up showing the one for onPlayerJoin first

[mjbvz]

Here's the complete tsserver request:

[Trace  - 11:25:14 AM] <semantic> Sending request: signatureHelp (47). Response expected: yes. Current queue length: 0
Arguments: {
    "file": "/Users/matb/projects/san/x.ts",
    "line": 4,
    "offset": 30,
    "triggerReason": {
        "kind": "invoked"
    }
}
[Trace  - 11:25:14 AM] <semantic> Response received: signatureHelp (47). Request took 5 ms. Success: true 
Result: {
    "items": [
        {
            "isVariadic": false,
            "prefixDisplayParts": [
                {
                    "text": "addEventHandler",
                    "kind": "functionName"
                },
                {
                    "text": "(",
                    "kind": "punctuation"
                }
            ],
            "suffixDisplayParts": [
                {
                    "text": ")",
                    "kind": "punctuation"
                },
                {
                    "text": ":",
                    "kind": "punctuation"
                },
                {
                    "text": " ",
                    "kind": "space"
                },
                {
                    "text": "void",
                    "kind": "keyword"
                }
            ],
            "separatorDisplayParts": [
                {
                    "text": ",",
                    "kind": "punctuation"
                },
                {
                    "text": " ",
                    "kind": "space"
                }
            ],
            "parameters": [
                {
                    "name": "event",
                    "documentation": [],
                    "displayParts": [
                        {
                            "text": "event",
                            "kind": "parameterName"
                        },
                        {
                            "text": ":",
                            "kind": "punctuation"
                        },
                        {
                            "text": " ",
                            "kind": "space"
                        },
                        {
                            "text": "\"onPlayerJoin\"",
                            "kind": "stringLiteral"
                        }
                    ],
                    "isOptional": false
                },
                {
                    "name": "x",
                    "documentation": [],
                    "displayParts": [
                        {
                            "text": "x",
                            "kind": "parameterName"
                        },
                        {
                            "text": ":",
                            "kind": "punctuation"
                        },
                        {
                            "text": " ",
                            "kind": "space"
                        },
                        {
                            "text": "number",
                            "kind": "keyword"
                        }
                    ],
                    "isOptional": false
                }
            ],
            "documentation": [],
            "tags": []
        },
        {
            "isVariadic": false,
            "prefixDisplayParts": [
                {
                    "text": "addEventHandler",
                    "kind": "functionName"
                },
                {
                    "text": "(",
                    "kind": "punctuation"
                }
            ],
            "suffixDisplayParts": [
                {
                    "text": ")",
                    "kind": "punctuation"
                },
                {
                    "text": ":",
                    "kind": "punctuation"
                },
                {
                    "text": " ",
                    "kind": "space"
                },
                {
                    "text": "void",
                    "kind": "keyword"
                }
            ],
            "separatorDisplayParts": [
                {
                    "text": ",",
                    "kind": "punctuation"
                },
                {
                    "text": " ",
                    "kind": "space"
                }
            ],
            "parameters": [
                {
                    "name": "event",
                    "documentation": [],
                    "displayParts": [
                        {
                            "text": "event",
                            "kind": "parameterName"
                        },
                        {
                            "text": ":",
                            "kind": "punctuation"
                        },
                        {
                            "text": " ",
                            "kind": "space"
                        },
                        {
                            "text": "\"onPlayerQuit\"",
                            "kind": "stringLiteral"
                        }
                    ],
                    "isOptional": false
                },
                {
                    "name": "y",
                    "documentation": [],
                    "displayParts": [
                        {
                            "text": "y",
                            "kind": "parameterName"
                        },
                        {
                            "text": ":",
                            "kind": "punctuation"
                        },
                        {
                            "text": " ",
                            "kind": "space"
                        },
                        {
                            "text": "string",
                            "kind": "keyword"
                        }
                    ],
                    "isOptional": false
                }
            ],
            "documentation": [],
            "tags": []
        }
    ],
    "applicableSpan": {
        "start": {
            "line": 4,
            "offset": 17
        },
        "end": {
            "line": 4,
            "offset": 31
        }
    },
    "selectedItemIndex": 0,
    "argumentIndex": 0,
    "argumentCount": 1
}

[mjbvz]

Ben Lichtman (@uniqueiniquity) Is this an example of the signature help issue we talked about on Wednesday?

[uniqueiniquity]

Not quite - the issue I mentioned was more related to the behavior of an existing sig help session, rather than triggering a new one. I agree with the desire here for tsserver to return selectedItemIndex: 1 based on the context of the trigger location, though.