Infinite loop getting completions when finding preceding matching token in JSDoc

[dsherret]

Bug Report

The infinite loop happens here:

TypeScript/src/services/utilities.ts

Lines 1935 to 1952 in d5fd34b

	while (true) {
	const preceding = findPrecedingToken(token.getFullStart(), sourceFile);
	if (!preceding) {
	return undefined;
	}
	token = preceding;
	if (token.kind === matchingTokenKind) {
	if (remainingMatchingTokens === 0) {
	return token;
	}
	remainingMatchingTokens--;
	}
	else if (token.kind === tokenKind) {
	remainingMatchingTokens++;
	}
	}

More specifically, findPrecedingToken returns back the current token, so remainingMatchingTokens keeps getting incremented.

🔎 Search Terms

infinite loop completions jsdoc

🕗 Version & Regression Information

5.0.2 and I can reproduce it in main. It probably occurred in older versions.

⏯ Playground Link

I can't reproduce it in the playground.

💻 Code

1. Take the following starting code:

/// <reference path="./compiler.d.ts" />

(window => {
  /** @type {DenoCore} */
  const core = window.Deno.core;
})();

2. Type /** @ before window:

/// <reference path="./compiler.d.ts" />

(/** @window => {
  /** @type {DenoCore} */
  const core = window.Deno.core;
})();

3. Hover over window.

🙁 Actual behavior

Hangs forever.

🙂 Expected behavior

Not hang.

Test case

import * as ts from "../../_namespaces/ts";

describe("unittests:: services:: utilities", () => {
  describe("Test findPrecedingMatchingToken,", () => {
    it("should not infinite loop finding opening brace", () => {
      const sourceFile = ts.createSourceFile("file.ts", `/// <reference path="./compiler.d.ts" />

(/** @window => {
  /** @type {Abcd123} */
  const core = window.Abcd.core;
})();`, ts.ScriptTarget.ESNext, true);
      // can't use ts.getTokenAtPosition because it returns back the wrong token
      const param = ts.forEachChildRecursively(sourceFile, node => node.kind === ts.SyntaxKind.Parameter ? node : undefined)!;
      const jsDoc = param.getChildren()[0];
      const token = jsDoc.getLastToken()!;
      const result = ts.findPrecedingMatchingToken(token, ts.SyntaxKind.OpenBraceToken, sourceFile);
      // will never happen
      console.log(result);
    });
  });
});

I was looking into this a bit, but I need to move on to other things so I'm just logging it.