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scapegoat-scala / scapegoat

Scala compiler plugin for static code analysis
Apache License 2.0
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Enhancement: unused public methods #41

Open RichardBradley opened 10 years ago

RichardBradley commented 10 years ago

For standalone projects (i.e. not libraries), unused public methods are a nuisance that can be hard to track down.

Possibly scapegoat could detect these and warn?

The difficulty with this inspection is that it is completely inapplicable to many projects (i.e. those intended as libraries).

sksamuel commented 10 years ago

I am introducing opt in inspections so that's not an issue (that libraries don't want it as it can be opt in) On 14 Aug 2014 18:01, "Richard Bradley" notifications@github.com wrote:

For standalone projects (i.e. not libraries), unused public methods are a nuisance that can be hard to track down.

Possibly scapegoat could detect these and warn?

The difficulty with this inspection is that it is completely inapplicable to many projects (i.e. those intended as libraries).

— Reply to this email directly or view it on GitHub https://github.com/sksamuel/scalac-scapegoat-plugin/issues/41.

rorygraves commented 10 years ago

Lol, weird sksamuel and I were talking about deeper code inspections like this one.

I guess this one is easy for public methods. You would want a clear documentation for switching it on/off in the config (possibly in the message itself).

On 14 Aug 2014, at 18:01, Richard Bradley notifications@github.com wrote:

For standalone projects (i.e. not libraries), unused public methods are a nuisance that can be hard to track down.

Possibly scapegoat could detect these and warn?

The difficulty with this inspection is that it is completely inapplicable to many projects (i.e. those intended as libraries).

— Reply to this email directly or view it on GitHub.

rorygraves commented 10 years ago

I think one of the challenges with this inspection is the interesting cases rapidly devolve into graph walking the entire code. E.g. a method overrides a trait. To determine if the method is dead you need to find all instances of calls to the trait (only if somebody ever creates an instance). I think good dead code detection is going to take some interesting deep code analysis. This is something I'm really interested in and am hoping to use the core of the Ensime project to do it.

sksamuel commented 10 years ago

I think it would be reasonably straightforward but a bit of trail of error to do this:

For every method declaration add it to a list of declared methods For every method invocation add it to a list of invoked methods

After walking the entire graph, declarations - invocations are unused. This doesn't account for traits or superclasses which might need a bit more work.

On 14 August 2014 18:30, Rory notifications@github.com wrote:

I think one of the challenges with this inspection is the interesting cases rapidly devolve into graph walking the entire code. E.g. a method overrides a trait. To determine if the method is dead you need to find all instances of calls to the trait (only if somebody ever creates an instance). I think good dead code detection is going to take some interesting deep code analysis. This is something I'm really interested in and am hoping to use the core of the Ensime project to do it.

— Reply to this email directly or view it on GitHub https://github.com/sksamuel/scalac-scapegoat-plugin/issues/41#issuecomment-52214948 .

rorygraves commented 10 years ago

Its definitely worth a try. I would love to see this working and would be a cool win for scapegoat.