bug: Autocompletion extension gives different results for same prefix

[sarah-mdv]

Does this issue occur when all extensions are disabled?: Yes

• VS Code Version: 1.68.0
• OS Version: Windows 11

Steps to Reproduce:

1. Start typing a prefix as shown below:
   
2. Press escape
3. Press ctrl+space to retrigger Intellisense
   

Now only these options appear.

For all autocompletion items, the label is the filterText.

[vscodenpa]

Thanks for creating this issue! We figured it's missing some basic information or in some other way doesn't follow our issue reporting guidelines. Please take the time to review these and update the issue.

Happy Coding!

[sarah-mdv]

@jrieken
I'd be happy to provide more information. How can I help ?

[jrieken]

provide a complete sample (as source code!), name the language you are using, and the extension providing the results

[sarah-mdv]

Language: Clickhouse SQL
The extension is a private extension that isn't yet available on the Marketplace but is a language support tool for Clickhouse SQL

The completionItemProviders are as follows:

const dbProvider = vscode.languages.registerCompletionItemProvider(config.get("language.suffix"), {
	async provideCompletionItems(document: vscode.TextDocument, position: vscode.Position, token: vscode.CancellationToken, context: vscode.CompletionContext) { 

		let suggestions: vscode.CompletionItem[] = await databaseDataCompletion.getClickhouseMetadataCompletionItems()

		// There are two autocompletion-sources for the Clickhouse-Function-Names: Metadata returned from Clickhouse (`system.functions` table), and hardcoded function-headers. In case we have hardcoded information, the metadata from clickhouse is ignored.
		suggestions = suggestions.filter(item => !((FUNCTION_COMPLETIONS.map(func => func.name)).includes((item.label.toString()))))

		return suggestions
	}
})
context.subscriptions.push(dbProvider)

/**
 * This autocompletion provider provides function completion with argument types. 
 * When a function is autocompleted, the arguments of appropriate types are offered as options for each argument
 */
const functionArgumentProvider = vscode.languages.registerCompletionItemProvider(config.get("language.suffix") ,{
	async provideCompletionItems(document: vscode.TextDocument, position: vscode.Position, token: vscode.CancellationToken, context: vscode.CompletionContext) { 

		const snippets: Snippet[] = await getFunctionSnippets(databaseDataCompletion, FUNCTION_COMPLETIONS)
		
		const snippetCompletionItems: vscode.CompletionItem[] = snippets.map(snippet => {
			const cItem = new vscode.CompletionItem(snippet.name, vscode.CompletionItemKind.Snippet)
			cItem.insertText = new vscode.SnippetString(snippet.body)
			cItem.documentation = snippet.documentation
			return cItem
		})
		return snippetCompletionItems
	}
	})
context.subscriptions.push(functionArgumentProvider)

Let me know what other info you need.

[jrieken]

A completion item provider is invoked, returns completions but they don't show up! 😕 What's the issue? Filtering! Filtering compares completions with a prefix and hides those that don't match.

Example

• trigger completions here: say.he| (| is the cursor)
• provider returns abc, help, hood
• the editor takes the he-prefix and scores it against abc, help, and hood.
• scoring yields these result:
  • abc - no match, don't show
  • help - good match, show
  • hood - no match, only h occurs, don't show
• editor shows help suggestion, does not show abc and hood suggestion

Extensions Rule!

The above sample was using "defaults" to determine the prefix and the filter criteria.

• prefix: each completion can define its very own prefix via vscode.CompletionItem#range. Taking the example above, valid prefixes can be say.he or .he or (the empty string). Any range is valid as long as it includes the cursor position and is single line only.
• filter: each completion can define what string to use when filtering. The default is the label but via vscode.CompletionItem#filterText any string can be defined

When to use what? It depends on the language, its word definition, and if you control/understand the word definition or not. The defaults usually work well enough but some languages might use a non-intuitive word definition, or completions span multiple words, or completions include non-word character etc. In all those cases the range-property should be used.

[sarah-mdv]

Ok, thanks for taking the time to answer !