code unreachable rule

[michelkluger]

If you have a question about a behavior that you’re seeing in pyright, consider posting to the Pyright discussion forum.

Is your feature request related to a problem? Please describe.
pylance singals when code is unreachable would be nice to get a CI error via pyright

Describe the solution you’d like
A rule to report unreachable code

[erictraut]

This is a duplicate of this issue. It has received no upvotes in four years.

[michelkluger]

This is a duplicate of this issue. It has received no upvotes in four years.

maybe would be nicer to implement it, I am sure many people and codebases will benefit from it, dont see what would be the negative of having such a rule

[michelkluger]

how many upvotes we need it to get it implemented? @erictraut

[erictraut]

As I mention in the other thread, there are many legitimate situations where unreachable code exists in a code base. That means there will be quite a few false positives for such a rule. It also means that such a rule could not be enabled by default even in strict mode. I generally don't like adding new rules that cannot be enabled by default even in strict mode because they are hard for users to discover, and therefore they rarely get used.

For those reasons, I'm not convinced this rule is a good idea. I'd need to see a lot of upvotes to be convinced otherwise.

[michelkluger]

I'd need to see a lot of upvotes to be convinced otherwise.

how many?

[erictraut]

how many?

That's sufficient :)

I've added a new diagnostic check called reportUnreachable. It is off by default even in strict mode. It reports a diagnostic for code that is determined to be structurally unreachable (e.g. after a return statement) or unreachable via type analysis (a type guard that narrows the type of an expression to Never).

This will be included in the next release.

[erictraut]

This is addressed in pyright 1.1.402.