"Convert to anonymous object" intention: suggest for kotlin fun interface

#KT-37749 Fixed

idea/src/org/jetbrains/kotlin/idea/intentions/SamConversionToAnonymousObjectIntention.kt

@@ -15,11 +15,10 @@ import org.jetbrains.kotlin.idea.KotlinBundle
 import org.jetbrains.kotlin.idea.caches.resolve.analyze
 import org.jetbrains.kotlin.idea.caches.resolve.resolveToCall
 import org.jetbrains.kotlin.idea.core.replaced
-import org.jetbrains.kotlin.idea.search.usagesSearch.descriptor
 import org.jetbrains.kotlin.lexer.KtTokens
-import org.jetbrains.kotlin.load.java.descriptors.JavaClassDescriptor
 import org.jetbrains.kotlin.load.java.sam.JavaSingleAbstractMethodUtils
 import org.jetbrains.kotlin.psi.KtCallExpression
+import org.jetbrains.kotlin.psi.KtFunctionLiteral
 import org.jetbrains.kotlin.psi.KtLambdaExpression
 import org.jetbrains.kotlin.psi.KtPsiFactory
 import org.jetbrains.kotlin.psi.psiUtil.anyDescendantOfType
@@ -39,13 +38,12 @@ class SamConversionToAnonymousObjectIntention : SelfTargetingRangeIntention<KtCa
         val callee = element.calleeExpression ?: return null
         val lambda = getLambdaExpression(element) ?: return null
         val functionLiteral = lambda.functionLiteral
-        val descriptor = (functionLiteral.descriptor as? FunctionDescriptor) ?: return null
         val bindingContext = functionLiteral.analyze()
         val sam = element.getSingleAbstractMethod(bindingContext) ?: return null
 
         val samValueParameters = sam.valueParameters
         val samValueParameterSize = samValueParameters.size
-        if (descriptor.valueParameters.size != samValueParameterSize) return null
+        if (samValueParameterSize != functionLiteral.functionDescriptor(bindingContext)?.valueParameters?.size) return null
 
         val samName = sam.name.asString()
         if (functionLiteral.anyDescendantOfType<KtCallExpression> { call ->
@@ -65,18 +63,22 @@ class SamConversionToAnonymousObjectIntention : SelfTargetingRangeIntention<KtCa
 
     override fun applyTo(element: KtCallExpression, editor: Editor?) {
         val lambda = getLambdaExpression(element) ?: return
-        val functionDescriptor = lambda.functionLiteral.descriptor as? FunctionDescriptor ?: return
-        val functionName = element.getSingleAbstractMethod(element.analyze(BodyResolveMode.PARTIAL))?.name?.asString() ?: return
+        val context = element.analyze(BodyResolveMode.PARTIAL)
+        val functionDescriptor = lambda.functionLiteral.functionDescriptor(context) ?: return
+        val functionName = element.getSingleAbstractMethod(context)?.name?.asString() ?: return
         convertToAnonymousObject(element, lambda, functionDescriptor, functionName)
     }
 
     private fun KtCallExpression.getSingleAbstractMethod(context: BindingContext): FunctionDescriptor? {
         val type = getType(context) ?: return null
         if (!JavaSingleAbstractMethodUtils.isSamType(type)) return null
-        val javaClass = type.constructor.declarationDescriptor as? JavaClassDescriptor ?: return null
-        return getSingleAbstractMethodOrNull(javaClass)
+        val classDescriptor = type.constructor.declarationDescriptor as? ClassDescriptor ?: return null
+        return getSingleAbstractMethodOrNull(classDescriptor)
     }
 
+    private fun KtFunctionLiteral.functionDescriptor(context: BindingContext): FunctionDescriptor? =
+        context[BindingContext.DECLARATION_TO_DESCRIPTOR, this] as? FunctionDescriptor
+
     companion object {
         fun convertToAnonymousObject(
             call: KtCallExpression,

idea/testData/intentions/samConversionToAnonymousObject/funInterface.kt

@@ -0,0 +1,9 @@
+fun interface KotlinFace {
+    fun single()
+}
+
+fun useSam(kf: KotlinFace) {}
+
+fun callSam() {
+    useSam(kf = <caret>KotlinFace {})
+}

idea/testData/intentions/samConversionToAnonymousObject/funInterface.kt.after

@@ -0,0 +1,13 @@
+fun interface KotlinFace {
+    fun single()
+}
+
+fun useSam(kf: KotlinFace) {}
+
+fun callSam() {
+    useSam(kf = object : KotlinFace {
+        override fun single() {
+
+        }
+    })
+}

idea/tests/org/jetbrains/kotlin/idea/intentions/IntentionTestGenerated.java

@@ -14790,6 +14790,11 @@ public class IntentionTestGenerated extends AbstractIntentionTest {
             KotlinTestUtils.assertAllTestsPresentByMetadataWithExcluded(this.getClass(), new File("idea/testData/intentions/samConversionToAnonymousObject"), Pattern.compile("^([\\w\\-_]+)\\.(kt|kts)$"), null, true);
         }
 
+        @TestMetadata("funInterface.kt")
+        public void testFunInterface() throws Exception {
+            runTest("idea/testData/intentions/samConversionToAnonymousObject/funInterface.kt");
+        }
+
         @TestMetadata("labeledReturn.kt")
         public void testLabeledReturn() throws Exception {
             runTest("idea/testData/intentions/samConversionToAnonymousObject/labeledReturn.kt");