False expression: Token end is child end 【I don't know what to call this issue]】

[Judu233]

Bug Report

 [error] <semantic> TypeScript Server Error (4.6.2)
Debug Failure. False expression: Token end is child end
Error: Debug Failure. False expression: Token end is child end
    at processChildNode (e:\vs code\Microsoft VS Code\resources\app\extensions\node_modules\typescript\lib\tsserver.js:144315:38)
    at e:\vs code\Microsoft VS Code\resources\app\extensions\node_modules\typescript\lib\tsserver.js:144255:21
    at visitNode (e:\vs code\Microsoft VS Code\resources\app\extensions\node_modules\typescript\lib\tsserver.js:29849:24)
    at Object.forEachChild (e:\vs code\Microsoft VS Code\resources\app\extensions\node_modules\typescript\lib\tsserver.js:29972:21)
    at processNode (e:\vs code\Microsoft VS Code\resources\app\extensions\node_modules\typescript\lib\tsserver.js:144254:20)
    at formatSpanWorker (e:\vs code\Microsoft VS Code\resources\app\extensions\node_modules\typescript\lib\tsserver.js:144055:17)
    at e:\vs code\Microsoft VS Code\resources\app\extensions\node_modules\typescript\lib\tsserver.js:144019:140
    at Object.getFormattingScanner (e:\vs code\Microsoft VS Code\resources\app\extensions\node_modules\typescript\lib\tsserver.js:142646:23)
    at Object.formatNodeGivenIndentation (e:\vs code\Microsoft VS Code\resources\app\extensions\node_modules\typescript\lib\tsserver.js:144019:31)
    at e:\vs code\Microsoft VS Code\resources\app\extensions\node_modules\typescript\lib\tsserver.js:129984:46
    at Object.flatMap (e:\vs code\Microsoft VS Code\resources\app\extensions\node_modules\typescript\lib\tsserver.js:508:25)
    at getEntryForMemberCompletion (e:\vs code\Microsoft VS Code\resources\app\extensions\node_modules\typescript\lib\tsserver.js:129982:38)
    at createCompletionEntry (e:\vs code\Microsoft VS Code\resources\app\extensions\node_modules\typescript\lib\tsserver.js:129802:23)
    at getCompletionEntriesFromSymbols (e:\vs code\Microsoft VS Code\resources\app\extensions\node_modules\typescript\lib\tsserver.js:130166:29)
    at completionInfoFromData (e:\vs code\Microsoft VS Code\resources\app\extensions\node_modules\typescript\lib\tsserver.js:129620:17)
    at Object.getCompletionsAtPosition (e:\vs code\Microsoft VS Code\resources\app\extensions\node_modules\typescript\lib\tsserver.js:129481:36)
    at Object.getCompletionsAtPosition (e:\vs code\Microsoft VS Code\resources\app\extensions\node_modules\typescript\lib\tsserver.js:161847:35)
    at IpcIOSession.Session.getCompletions (e:\vs code\Microsoft VS Code\resources\app\extensions\node_modules\typescript\lib\tsserver.js:173395:64)
    at Session.handlers.ts.Map.ts.getEntries._a.<computed> (e:\vs code\Microsoft VS Code\resources\app\extensions\node_modules\typescript\lib\tsserver.js:172237:61)
    at e:\vs code\Microsoft VS Code\resources\app\extensions\node_modules\typescript\lib\tsserver.js:174044:88
    at IpcIOSession.Session.executeWithRequestId (e:\vs code\Microsoft VS Code\resources\app\extensions\node_modules\typescript\lib\tsserver.js:174035:28)
    at IpcIOSession.Session.executeCommand (e:\vs code\Microsoft VS Code\resources\app\extensions\node_modules\typescript\lib\tsserver.js:174044:33)
    at IpcIOSession.Session.onMessage (e:\vs code\Microsoft VS Code\resources\app\extensions\node_modules\typescript\lib\tsserver.js:174070:35)
    at process.<anonymous> (e:\vs code\Microsoft VS Code\resources\app\extensions\node_modules\typescript\lib\tsserver.js:176705:31)
    at process.emit (events.js:315:20)
    at emit (internal/child_process.js:903:12)
    at processTicksAndRejections (internal/process/task_queues.js:81:21): Error: <semantic> TypeScript Server Error (4.6.2)

🔎 Search Terms

N/A since I'm not sure how to describe it.
It suddenly appeared at a certain moment. I don't know how to trigger it. I tried to reinstall vscode, but it didn't work

🕗 Version & Regression Information

vscode version:

ts version: 4.6.2

⏯ Playground Link

In playground link, it is normal

💻 Code

class A {
    $a(){

    }

    b(){

    }
}

class B extends A{
   //As long as there is input here, an error will be reported, and there is no type prompt
}

🙁 Actual behavior

🙂 Expected behavior

It should prompt the $a method and the b method

[a-tarasyuk]

escapeSnippetText adds \ for all $

TypeScript/src/services/completions.ts

Lines 1070 to 1077 in a4f5555

	write: s => baseWriter.write(escapeSnippetText(s)),
	nonEscapingWrite: baseWriter.write,
	writeLiteral: s => baseWriter.writeLiteral(escapeSnippetText(s)),
	writeStringLiteral: s => baseWriter.writeStringLiteral(escapeSnippetText(s)),
	writeSymbol: (s, symbol) => baseWriter.writeSymbol(escapeSnippetText(s), symbol),
	writeParameter: s => baseWriter.writeParameter(escapeSnippetText(s)),
	writeComment: s => baseWriter.writeComment(escapeSnippetText(s)),
	writeProperty: s => baseWriter.writeProperty(escapeSnippetText(s)),

formatting doesn't handle escaping \ because \$a (or \$\$a) is not a valid identifier.

TypeScript/src/services/completions.ts

Lines 995 to 1001 in a4f5555

	return formatting.formatNodeGivenIndentation(
	nodeWithPos,
	syntheticFile,
	sourceFile.languageVariant,
	/* indentation */ 0,
	/* delta */ 0,
	{ ...formatContext, options: formatOptions });

+1 related #48215 issue

Should TS Server return escaped snippet \$0? Or should only names be escaped \$\$a? I think we can call escapeSnippetText after formatting, just need to be sure that snippets \$0 have to be escaped too.

/cc @andrewbranch

[andrewbranch]

Oh good find @a-tarasyuk, I think it makes sense to do the escaping after formatting. If we really needed to, we could have the formatter ignore snippet nodes (there’s a property on the attached EmitNode IIRC) but if the simple solution of swapping the order of operations works, that’s great.

[a-tarasyuk]

If we really needed to, we could have the formatter ignore snippet nodes (there’s a property on the attached EmitNode IIRC)

Currently, the insertText response looks like this

"\\$\\$b(): `test\\${string}` {\n    $0\n}"

$0 is not escaped. And this source text breaks formatting. If we apply escapeSnippetText here

TypeScript/src/services/completions.ts

Line 1013 in a4f5555

return { insertText, isSnippet, importAdder, replacementSpan };

return { insertText: escapeSnippetText(insertText), isSnippet, importAdder, replacementSpan };

the response will be changed to

"\\$\\$b(): `test\\${string}` {\n    \\$0\n}"

Should TS Server return escaped snippet $0? Or should only names be escaped $$a?

Not sure if escaped snippets (\\$0) affect VSCode (or other clients) or not.

[andrewbranch]

Oh, right. The $0 placeholder needs to reach VS Code unescaped. So maybe the formatter does need to be aware of these snippet nodes.