Store descriptor via soft reference to avoid holding project from debugger

idea/src/org/jetbrains/kotlin/idea/debugger/stepping/KotlinBasicStepMethodFilter.kt

@@ -19,11 +19,11 @@ package org.jetbrains.kotlin.idea.debugger.stepping
 import com.intellij.debugger.engine.DebugProcessImpl
 import com.intellij.debugger.engine.NamedMethodFilter
 import com.intellij.util.Range
+import com.intellij.util.SofterReference
 import com.sun.jdi.Location
 import org.jetbrains.kotlin.builtins.functions.FunctionInvokeDescriptor
 import org.jetbrains.kotlin.descriptors.*
 import org.jetbrains.kotlin.descriptors.CallableMemberDescriptor.Kind.*
-import org.jetbrains.kotlin.descriptors.impl.AnonymousFunctionDescriptor
 import org.jetbrains.kotlin.idea.caches.resolve.resolveToDescriptor
 import org.jetbrains.kotlin.idea.core.getDirectlyOverriddenDeclarations
 import org.jetbrains.kotlin.idea.util.application.runReadAction
@@ -35,20 +35,24 @@ import org.jetbrains.kotlin.psi.psiUtil.getParentOfTypesAndPredicate
 import org.jetbrains.kotlin.resolve.DescriptorUtils
 
 class KotlinBasicStepMethodFilter(
-        private val targetDescriptor: CallableMemberDescriptor,
+        targetDescriptor: CallableMemberDescriptor,
         private val myCallingExpressionLines: Range<Int>
 ) : NamedMethodFilter {
-    private val myTargetMethodName = when (targetDescriptor) {
+    private val myTargetMethodName: String = when (targetDescriptor) {
         is ClassDescriptor, is ConstructorDescriptor -> "<init>"
         is PropertyAccessorDescriptor -> JvmAbi.getterName(targetDescriptor.correspondingProperty.name.asString())
         else -> targetDescriptor.name.asString()
     }
 
+    private val _targetDescriptor = SofterReference(targetDescriptor)
+
     override fun getCallingExpressionLines() = myCallingExpressionLines
 
     override fun getMethodName() = myTargetMethodName
 
     override fun locationMatches(process: DebugProcessImpl, location: Location): Boolean {
+        val targetDescriptor = _targetDescriptor.get() ?: return true
+
         val method = location.method()
         if (myTargetMethodName != method.name()) return false