Purity plugin IDE integration

[raulraja]

The original version of the purity plugin checks when a function returns Unit or contains calls in its body to other functions that it return Unit.

This plugin should show visually in the editor this is happening and provide intentions to refactor the function to become suspend. This is the IDE piece of the purity plugin.

[jansorg]

@raulraja Could you provide a pointer to the existing code of the purity plugin? I'm not seeing it in arrow-meta-protoype

[raulraja]

@i-walker was the last one fiddling with it

[i-walker]

@jansorg I started the plugin as an Inspection, but I don't had time, yet to figure out how to register an unregistered Extension to the IDE successfully.

In the ide dsl you would write something like this:

val IdeMetaPlugin.dummyIdePlugin: Plugin
  get() = "PurityIdePlugin" {
    meta(
      addLocalInspectionToolToIdeRegistry(),
      addApplicableInspection(
        defaultFixText = "Impure",
        inspectionHighlightType = { ProblemHighlightType.ERROR },
        kClass = KtNamedFunction::class.java,
        highlightingRange = { f -> f.textRange },
        inspectionText = { f -> "Function $f should be suspended" },
        applyTo = { f, project, editor ->
          f.addModifier(KtTokens.SUSPEND_KEYWORD)
        },
        isApplicable = { f: KtNamedFunction ->
          f.nameIdentifier != null && !f.hasModifier(KtTokens.SUSPEND_KEYWORD) &&
            f.resolveToDescriptorIfAny()?.run {
              !isSuspend && (ReturnsCheck.ReturnsUnit.check(this) || ExtendedReturnsCheck.ReturnsNothing.check(this)
                || ExtendedReturnsCheck.ReturnsNullableNothing.check(this))
            } == true
        }
      )
    )
  }

fun IdeMetaPlugin.addLocalInspectionToolToIdeRegistry(): ExtensionPhase =
    registerExtensionPoint(
      EP_NAME,
      LocalInspectionTool::class.java
    )

This is a simplified version from our legacy attempt here:
https://github.com/arrow-kt/arrow-meta-prototype/blob/8afa971fb60f629dee02ad5ea698269f7772e2a8/compiler-plugin/src/main/java/arrow/plugin/MetaClassBuilderInterceptorExtension.kt

The problem is that even though I can debug that addLocalInspectionToolToIdeRegistry, works. The inspection is not there every time I run the Ide instance.

[i-walker]

We should keep that open because we're still working on traversing and resolving the type of each Call of a Function.
This code would not be inspected by the current purity plugin:

object Impure {
    fun sideEffect()=
        println("BOOM!")

    suspend fun other(): Unit {
        println("other")
    }

    val x = { println() }

    fun another2(): String {
        1; println("test");
        {
            { println() }
        }()
        return "another"
    }
}