Add "Make variable immutable" quickfix for const #KT-24263 Fixed

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

@@ -23,6 +23,7 @@ import org.jetbrains.kotlin.descriptors.DeclarationDescriptor
 import org.jetbrains.kotlin.diagnostics.Diagnostic
 import org.jetbrains.kotlin.diagnostics.DiagnosticFactory1
 import org.jetbrains.kotlin.diagnostics.Errors
+import org.jetbrains.kotlin.lexer.KtToken
 import org.jetbrains.kotlin.lexer.KtTokens
 import org.jetbrains.kotlin.psi.*
 import org.jetbrains.kotlin.psi.psiUtil.getStrictParentOfType
@@ -98,5 +99,14 @@ class ChangeVariableMutabilityFix(
                 return ChangeVariableMutabilityFix(property, makeVar = true)
             }
         }
+
+        val CONST_VAL_FACTORY = object : KotlinSingleIntentionActionFactory() {
+            override fun createAction(diagnostic: Diagnostic): IntentionAction? {
+                val (modifier, element) = Errors.WRONG_MODIFIER_TARGET.cast(diagnostic).run { a to psiElement }
+                if (modifier != KtTokens.CONST_KEYWORD) return null
+                val property = element.getStrictParentOfType<KtProperty>() ?: return null
+                return ChangeVariableMutabilityFix(property, makeVar = false)
+            }
+        }
     }
 }

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

@@ -137,7 +137,7 @@ class QuickFixRegistrar : QuickFixContributor {
             removeModifierFactory
         )
         REDUNDANT_MODIFIER_IN_GETTER.registerFactory(removeRedundantModifierFactory)
-        WRONG_MODIFIER_TARGET.registerFactory(removeModifierFactory)
+        WRONG_MODIFIER_TARGET.registerFactory(removeModifierFactory, ChangeVariableMutabilityFix.CONST_VAL_FACTORY)
         DEPRECATED_MODIFIER.registerFactory(ReplaceModifierFix)
         REDUNDANT_MODIFIER_FOR_TARGET.registerFactory(removeModifierFactory)
         WRONG_MODIFIER_CONTAINING_DECLARATION.registerFactory(removeModifierFactory)

idea/testData/quickfix/typeOfAnnotationMember/string.kt

@@ -1,5 +1,6 @@
 // "Replace array of boxed with array of primitive" "false"
 // ACTION: Put parameters on one line
+// ACTION: Convert to vararg parameter (may break code)
 annotation class SuperAnnotation(
         val str: <caret>Array<String>
 )

idea/testData/quickfix/variables/changeMutability/canBeVal/const.kt

@@ -0,0 +1,4 @@
+// "Make variable immutable" "true"
+object Test {
+    <caret>const var foo = "123"
+}

idea/testData/quickfix/variables/changeMutability/canBeVal/const.kt.after

@@ -0,0 +1,4 @@
+// "Make variable immutable" "true"
+object Test {
+    <caret>const val foo = "123"
+}

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

@@ -11762,6 +11762,11 @@ public class QuickFixTestGenerated extends AbstractQuickFixTest {
                     KotlinTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("idea/testData/quickfix/variables/changeMutability/canBeVal"), Pattern.compile("^([\\w\\-_]+)\\.kt$"), TargetBackend.ANY, true);
                 }
 
+                @TestMetadata("const.kt")
+                public void testConst() throws Exception {
+                    runTest("idea/testData/quickfix/variables/changeMutability/canBeVal/const.kt");
+                }
+
                 @TestMetadata("multiVariable.kt")
                 public void testMultiVariable() throws Exception {
                     runTest("idea/testData/quickfix/variables/changeMutability/canBeVal/multiVariable.kt");