Getting type information for a node causes other nodes to return any for their type

Bug Report

🔎 Search Terms

Compiler API, unexpected any

🕗 Version & Regression Information

• This changed between versions 4.5.x and 4.6.x

This does not repro on 4.5.5, but repros against v4.6.2

⏯ Playground Link

Playground link with relevant code

💻 Code

export function getFutureVersion(baseVersion?: string): number[] {
  const toRelease: number[] = [];
  const baseRelease: number[] = [];
  return baseRelease.map((_, index) => {
    const toPart = toRelease[index] ?? 0;
    if (index < 1) {
      return toPart;
    }
    if (index === 1) {
      toPart;
      //  ^? any
      toPart.lol; // Property 'lol' does not exist on type 'number'.(2339)
      //  ^? any
      return toPart + (baseVersion === undefined ? 0 : 1); 
    }
    return 0;
  });
}

🙁 Actual behavior

You can see that in this repro intellisense reports the type of toPart as any even though TS also knows that it must be a number.

If I attempt to get the type of toPart:

window.sandbox.createTSProgram().then(program => {
  program.emit()
  const ast = program.getSourceFile('/input.tsx');
  console.log(
    program.getTypeChecker().getTypeAtLocation(
      ast.statements[0].body.statements[2].expression.arguments[0].body.statements[2].thenStatement.statements[0].expression,
    ),
  );
});

// -> {checker: {…}, flags: 1, id: 1, intrinsicName: 'any', objectFlags: 0}

Hazarding a guess intellisense and the ^? playground token both just use checker.getTypeAtLocation(node) to get the type (and checker.typeToString to print it).

If you switch the TS version to 4.5 then you’ll see that the type is correctly printed as number and the above snippet logs:

{checker: {…}, flags: 8, id: 14, intrinsicName: 'number', objectFlags: 0}

🙂 Expected behavior

The 4.5 behaviour is correct - getTypeAtLocation should return a number type.

Related

https://github.com/typescript-eslint/typescript-eslint/issues/4689

[bradzacher]

@RyanCavanaugh this repro just depends on TS using 4.7.0-dev.20220418: https://github.com/bradzacher/TS-48313-REPRO/tree/main

[gabritto]

This issue appears to be fixed in the 4.7 nightly: https://www.typescriptlang.org/play?noUncheckedIndexedAccess=true&useUnknownInCatchVariables=true&noFallthroughCasesInSwitch=true&noImplicitOverride=true&ts=4.7.0-dev.20220331#code/KYDwDg9gTgLgBAMwK4DsDGMCWEVwObAwBiSMSUwAasFAM7YoAUARgIa1U304D8AXHFowomFHgCUAlEgC2zGgG0AunADeAKDhw0OIXBgQASsAA2wdsCmz5UZXAC8cZQG5N23fDYdjZi1bmKKo4ubhRkULhewD7mHAB0MqxgjIwA+gA0cKIAJqDiDgB8am5aOih6BgAKrLAO+kamscAKOaAqPDxwAAyuWlqYCHCMrSBwADxwAIz5Gn19YeS4VTUwvX0AviVZg8MouaP2h1MzW1rLsGtzAPRXWgB6PKf11bBxJhAmznA3cJVQEGAaDAAJ5wADk7xMYLg2QgwFocBQEHgoEwehw+mBgPB0gCUDBcUYACYAMwkgCc4iePzgDyeCwizxWcAA1EMotQ6AwHEdULkEKJgNk4J0unABNMvltNnMGbgem51uJXOsgA @bradzacher Do you think you can try and see if any of the original issues in https://github.com/typescript-eslint/typescript-eslint/issues/4689 are also fixed in the nightly version?