FIR: Support callable references to vars

^KT-32725 In Progress

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/ResolveUtils.kt

@@ -228,10 +228,11 @@ fun createFunctionalType(
 
 fun createKPropertyType(
     receiverType: ConeKotlinType?,
-    rawReturnType: ConeKotlinType
+    rawReturnType: ConeKotlinType,
+    isMutable: Boolean
 ): ConeLookupTagBasedType {
     val arguments = if (receiverType != null) listOf(receiverType, rawReturnType) else listOf(rawReturnType)
-    val classId = StandardClassIds.reflectByName("KProperty${arguments.size - 1}")
+    val classId = StandardClassIds.reflectByName("K${if (isMutable) "Mutable" else ""}Property${arguments.size - 1}")
     return ConeClassTypeImpl(ConeClassLikeLookupTagImpl(classId), arguments.toTypedArray(), isNullable = false)
 }
 

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/calls/ResolverParts.kt

@@ -237,7 +237,7 @@ private fun createKPropertyType(
 ): ConeKotlinType {
     val propertyType = returnTypeRef.coneTypeSafe<ConeKotlinType>() ?: ConeKotlinErrorType("No type for of $property")
     return createKPropertyType(
-        receiverType, propertyType
+        receiverType, propertyType, isMutable = property.isVar
     )
 }
 

compiler/fir/resolve/testData/diagnostics/callableReferences/varProperties.kt

@@ -0,0 +1,16 @@
+import kotlin.reflect.KMutableProperty0
+import kotlin.reflect.KMutableProperty1
+
+class A {
+    var bar: Int = 1
+}
+
+var bar = 1
+
+fun foo1(x: KMutableProperty0<Int>) {}
+fun foo2(x: KMutableProperty1<A, Int>) {}
+
+fun main() {
+    foo1(::bar)
+    foo2(A::bar)
+}

compiler/fir/resolve/testData/diagnostics/callableReferences/varProperties.txt

@@ -0,0 +1,22 @@
+FILE: varProperties.kt
+    public final class A : R|kotlin/Any| {
+        public constructor(): R|A| {
+            super<R|kotlin/Any|>()
+        }
+
+        public final var bar: R|kotlin/Int| = Int(1)
+            public get(): R|kotlin/Int|
+            public set(value: R|kotlin/Int|): R|kotlin/Unit|
+
+    }
+    public final var bar: R|kotlin/Int| = Int(1)
+        public get(): R|kotlin/Int|
+        public set(value: R|kotlin/Int|): R|kotlin/Unit|
+    public final fun foo1(x: R|kotlin/reflect/KMutableProperty0<kotlin/Int>|): R|kotlin/Unit| {
+    }
+    public final fun foo2(x: R|kotlin/reflect/KMutableProperty1<A, kotlin/Int>|): R|kotlin/Unit| {
+    }
+    public final fun main(): R|kotlin/Unit| {
+        R|/foo1|(::R|/bar|)
+        R|/foo2|(Q|A|::R|/A.bar|)
+    }

compiler/fir/resolve/tests/org/jetbrains/kotlin/fir/FirDiagnosticsTestGenerated.java

@@ -135,6 +135,11 @@ public class FirDiagnosticsTestGenerated extends AbstractFirDiagnosticsTest {
             runTest("compiler/fir/resolve/testData/diagnostics/callableReferences/simpleNoReceiver.kt");
         }
 
+        @TestMetadata("varProperties.kt")
+        public void testVarProperties() throws Exception {
+            runTest("compiler/fir/resolve/testData/diagnostics/callableReferences/varProperties.kt");
+        }
+
         @TestMetadata("compiler/fir/resolve/testData/diagnostics/callableReferences/fromBasicDiagnosticTests")
         @TestDataPath("$PROJECT_ROOT")
         @RunWith(JUnit3RunnerWithInners.class)