Fairly new to the PSI api, I’ve only used the IR api so far. With type resolution enabled I’m having...

# detekt

[Tim Oltjenbruns]

Fairly new to the PSI api, I’ve only used the IR api so far. With type resolution enabled I’m having a pretty hard time getting a function’s return type. I’m resorting to a mishmash of mutliple different BindingContext slices to determine the type, but it seems like there must be a better way.

May be a #compiler question, but there they seem to have success with just

bindingContext.get(BindingContext.EXPRESSION_TYPE_INFO, expression)

So I’m wondering if it may be something specific to how Detekt acquires the BindingContext?

[gammax]

Have your tried that with Detekt? Is it working?

[Tim Oltjenbruns]

I have. It is returning null on a lot of different cases.

[Tim Oltjenbruns]

I have to check other slices and cross reference many other parts to get the full picture.

[Tim Oltjenbruns]

I check these slices in this order
• bindingContext.get(BindingContext.EXPRESSION_TYPE_INFO, functionExpression)
• bindingContext.get(BindingContext.EXPRESSION_TYPE_INFO, functionExpression.bodyExpression)
• bindingContext.get(BindingContext.EXPECTED_RETURN_TYPE, functionExpression)
• Get the type of the last expression in the block body (unwrapping certain expressions like returns to get the actual type other than Nothing) But then I get the true type, not the type of what’s downcast.
• If there’s a body with no statements then I assume it’s Unit, for my purposes
• If it’s still null then: if its a KtNamedFunction I assume it’s Unit, otherwise it’s returning a class that isn’t in the Detekt classpath (Android SDK). Based on what I found during testing.
It works but I can’t help but think there’s a better way/

[Tim Oltjenbruns]

I’m writing a rule that checks for CQS. It attempts to identify side effects in Query style functions.

[t-kameyama]

private fun KtNamedFunction.returnType(): KotlinType? =
    (bindingContext[BindingContext.DECLARATION_TO_DESCRIPTOR, this] as? FunctionDescriptor)?.returnType

[Tim Oltjenbruns]

Works like a charm! Thank you!!