TaintTracking::FunctionModel: `FunctionOutput.isResult()` does not correspond to `FunctionOutput.isResult(0)`

[gagliardetto]

What currently happens

If a function returns only one result, then FunctionOutput.isResult() will work, and FunctionOutput.isResult(0) will not work.

If a function returns two or more results, then FunctionOutput.isResult(0) will work, and FunctionOutput.isResult() will not work.

What IMHO would be better

It would be a lot less error-prone and a lot more awesome to be able to write FunctionOutput.isResult(0) regardless of whether there is one result or more.

Why it would be an improvement over the current situation

It would be a lot harder to make errors (such as using FunctionOutput.isResult() when in reality the function returns more than one result) if FunctionOutput.isResult(0) and FunctionOutput.isResult() were equivalent regardless of the number of results returned by the function.

I believe this would make things simpler to the end-developer that will be writing codeql.

[gagliardetto]

Same for all other places where the usage of *Result(0) is valid only if len(results) > 1

[max-schaefer]

This sounds like a reasonable suggestion. @owen-mc, perhaps this is something you could look into once you're done with your current batch of issues?

[owen-mc]

Sure

[gagliardetto]

Thank you! 🚀