ChangeVariableMutability: diagnostic can be reported on constructor parameter

#KT-10416 Fixed

idea/src/org/jetbrains/kotlin/idea/quickfix/ChangeVariableMutabilityFix.kt

@@ -22,26 +22,31 @@ import com.intellij.openapi.project.Project
 import com.intellij.psi.PsiFile
 import org.jetbrains.kotlin.diagnostics.Diagnostic
 import org.jetbrains.kotlin.diagnostics.Errors
-import org.jetbrains.kotlin.psi.KtFile
-import org.jetbrains.kotlin.psi.KtProperty
-import org.jetbrains.kotlin.psi.KtPropertyAccessor
-import org.jetbrains.kotlin.psi.KtPsiFactory
+import org.jetbrains.kotlin.lexer.KtTokens
+import org.jetbrains.kotlin.psi.*
 import org.jetbrains.kotlin.resolve.DescriptorToSourceUtils
 
-public class ChangeVariableMutabilityFix(element: KtProperty, private val makeVar: Boolean) : KotlinQuickFixAction<KtProperty>(element) {
+public class ChangeVariableMutabilityFix(element: KtNamedDeclaration, private val makeVar: Boolean) : KotlinQuickFixAction<KtNamedDeclaration>(element) {
 
     override fun getText() = if (makeVar) "Make variable mutable" else "Make variable immutable"
 
     override fun getFamilyName(): String = getText()
 
     override fun isAvailable(project: Project, editor: Editor?, file: PsiFile): Boolean {
-        return element.isVar() != makeVar
+        return when (element) {
+            is KtProperty -> element.isVar != makeVar
+            is KtParameter -> (element.valOrVarKeyword == KtTokens.VAR_KEYWORD) != makeVar
+            else -> false
+        }
     }
 
     override fun invoke(project: Project, editor: Editor?, file: KtFile) {
         val factory = KtPsiFactory(project)
         val newKeyword = if (makeVar) factory.createVarKeyword() else factory.createValKeyword()
-        element.getValOrVarKeyword().replace(newKeyword)
+        when (element) {
+            is KtProperty -> element.valOrVarKeyword.replace(newKeyword)
+            is KtParameter -> element.valOrVarKeyword!!.replace(newKeyword)
+        }
     }
 
     companion object {
@@ -56,14 +61,18 @@ public class ChangeVariableMutabilityFix(element: KtProperty, private val makeVa
         public val VAL_REASSIGNMENT_FACTORY: KotlinSingleIntentionActionFactory = object: KotlinSingleIntentionActionFactory() {
             override fun createAction(diagnostic: Diagnostic): IntentionAction? {
                 val propertyDescriptor = Errors.VAL_REASSIGNMENT.cast(diagnostic).getA()
-                val declaration = DescriptorToSourceUtils.descriptorToDeclaration(propertyDescriptor) as? KtProperty ?: return null
+                val declaration = DescriptorToSourceUtils.descriptorToDeclaration(propertyDescriptor) as? KtNamedDeclaration ?: return null
                 return ChangeVariableMutabilityFix(declaration, true)
             }
         }
 
         public val VAR_OVERRIDDEN_BY_VAL_FACTORY: KotlinSingleIntentionActionFactory = object: KotlinSingleIntentionActionFactory() {
             override fun createAction(diagnostic: Diagnostic): IntentionAction? {
-                return ChangeVariableMutabilityFix(diagnostic.getPsiElement() as KtProperty, true)
+                val element = diagnostic.psiElement
+                return when (element) {
+                    is KtProperty, is KtParameter -> ChangeVariableMutabilityFix(element as KtNamedDeclaration, true)
+                    else -> null
+                }
             }
         }
     }

idea/testData/quickfix/variables/changeMutability/valOverrideVarConstructorParameter.kt

@@ -0,0 +1,6 @@
+// "Make variable mutable" "true"
+open class A {
+    open var x = 42;
+}
+
+class B(override val<caret> x: Int) : A()

idea/testData/quickfix/variables/changeMutability/valOverrideVarConstructorParameter.kt.after

@@ -0,0 +1,6 @@
+// "Make variable mutable" "true"
+open class A {
+    open var x = 42;
+}
+
+class B(override var x: Int) : A()

idea/testData/quickfix/variables/changeMutability/valReassignmentPropertyConstructorParameter.kt

@@ -0,0 +1,6 @@
+// "Make variable mutable" "true"
+class A(val a: Int) {
+    fun foo() {
+        <caret>a = 5
+    }
+}

idea/testData/quickfix/variables/changeMutability/valReassignmentPropertyConstructorParameter.kt.after

@@ -0,0 +1,6 @@
+// "Make variable mutable" "true"
+class A(var a: Int) {
+    fun foo() {
+        a = 5
+    }
+}

idea/tests/org/jetbrains/kotlin/idea/quickfix/QuickFixTestGenerated.java

@@ -7310,6 +7310,12 @@ public class QuickFixTestGenerated extends AbstractQuickFixTest {
                 doTest(fileName);
             }
 
+            @TestMetadata("valOverrideVarConstructorParameter.kt")
+            public void testValOverrideVarConstructorParameter() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("idea/testData/quickfix/variables/changeMutability/valOverrideVarConstructorParameter.kt");
+                doTest(fileName);
+            }
+
             @TestMetadata("valReassignmentLocal.kt")
             public void testValReassignmentLocal() throws Exception {
                 String fileName = KotlinTestUtils.navigationMetadata("idea/testData/quickfix/variables/changeMutability/valReassignmentLocal.kt");
@@ -7328,6 +7334,12 @@ public class QuickFixTestGenerated extends AbstractQuickFixTest {
                 doTest(fileName);
             }
 
+            @TestMetadata("valReassignmentPropertyConstructorParameter.kt")
+            public void testValReassignmentPropertyConstructorParameter() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("idea/testData/quickfix/variables/changeMutability/valReassignmentPropertyConstructorParameter.kt");
+                doTest(fileName);
+            }
+
             @TestMetadata("valWithSetter.kt")
             public void testValWithSetter() throws Exception {
                 String fileName = KotlinTestUtils.navigationMetadata("idea/testData/quickfix/variables/changeMutability/valWithSetter.kt");