For each parameter not used: handle char sequences correctly

An enhancement for KT-27209

idea/src/org/jetbrains/kotlin/idea/inspections/ForEachParameterNotUsedInspection.kt

@@ -34,6 +34,7 @@ class ForEachParameterNotUsedInspection : AbstractKotlinInspection() {
         private const val FOREACH_NAME = "forEach"
         private val COLLECTIONS_FOREACH_FQNAME = FqName("kotlin.collections.$FOREACH_NAME")
         private val SEQUENCES_FOREACH_FQNAME = FqName("kotlin.sequences.$FOREACH_NAME")
+        private val TEXT_FOREACH_FQNAME = FqName("kotlin.text.$FOREACH_NAME")
     }
 
     override fun buildVisitor(holder: ProblemsHolder, isOnTheFly: Boolean): PsiElementVisitor {
@@ -44,7 +45,7 @@ class ForEachParameterNotUsedInspection : AbstractKotlinInspection() {
             if (lambda == null || lambda.functionLiteral.arrow != null) return
             val context = it.analyze()
             when (it.getResolvedCall(context)?.resultingDescriptor?.fqNameOrNull()) {
-                COLLECTIONS_FOREACH_FQNAME, SEQUENCES_FOREACH_FQNAME -> {
+                COLLECTIONS_FOREACH_FQNAME, SEQUENCES_FOREACH_FQNAME, TEXT_FOREACH_FQNAME -> {
                     val descriptor = context[BindingContext.FUNCTION, lambda.functionLiteral] ?: return
                     val iterableParameter = descriptor.valueParameters.singleOrNull() ?: return
 
@@ -83,7 +84,7 @@ class ForEachParameterNotUsedInspection : AbstractKotlinInspection() {
     }
 
     private class ReplaceWithRepeatFix : LocalQuickFix {
-        override fun getFamilyName() = "Replace with 'repeat(size)'"
+        override fun getFamilyName() = "Replace with 'repeat()'"
 
         override fun applyFix(project: Project, descriptor: ProblemDescriptor) {
             val callExpression = descriptor.psiElement.parent as? KtCallExpression ?: return
@@ -92,8 +93,10 @@ class ForEachParameterNotUsedInspection : AbstractKotlinInspection() {
             val receiverClass =
                 receiverExpression.resolveToCall()?.resultingDescriptor?.returnType?.constructor?.declarationDescriptor as? ClassDescriptor
             val collection = callExpression.builtIns.collection
+            val charSequence = callExpression.builtIns.charSequence
             val sizeText = when {
                 receiverClass != null && DescriptorUtils.isSubclass(receiverClass, collection) -> "size"
+                receiverClass != null && DescriptorUtils.isSubclass(receiverClass, charSequence) -> "length"
                 else -> "count()"
             }
             val lambdaExpression = callExpression.lambdaArguments.singleOrNull()?.getArgumentExpression() ?: return

idea/testData/inspectionsLocal/forEachParameterNotUsed/repeat.kt

@@ -1,5 +1,5 @@
 // WITH_RUNTIME
-// FIX: Replace with 'repeat(size)'
+// FIX: Replace with 'repeat()'
 
 fun test(list: List<String>) {
     list.for<caret>Each {}

idea/testData/inspectionsLocal/forEachParameterNotUsed/repeat.kt.after

@@ -1,5 +1,5 @@
 // WITH_RUNTIME
-// FIX: Replace with 'repeat(size)'
+// FIX: Replace with 'repeat()'
 
 fun test(list: List<String>) {
     repeat(list.size) {}

idea/testData/inspectionsLocal/forEachParameterNotUsed/sequence.kt

@@ -1,5 +1,5 @@
 // WITH_RUNTIME
-// FIX: Replace with 'repeat(size)'
+// FIX: Replace with 'repeat()'
 
 fun test(sequence: Sequence<String>) {
     sequence.for<caret>Each {}

idea/testData/inspectionsLocal/forEachParameterNotUsed/sequence.kt.after

@@ -1,5 +1,5 @@
 // WITH_RUNTIME
-// FIX: Replace with 'repeat(size)'
+// FIX: Replace with 'repeat()'
 
 fun test(sequence: Sequence<String>) {
     repeat(sequence.count()) {}

idea/testData/inspectionsLocal/forEachParameterNotUsed/string.kt

@@ -0,0 +1,6 @@
+// WITH_RUNTIME
+// FIX: Replace with 'repeat()'
+
+fun test(s: String) {
+    s.for<caret>Each {}
+}

idea/testData/inspectionsLocal/forEachParameterNotUsed/string.kt.after

@@ -0,0 +1,6 @@
+// WITH_RUNTIME
+// FIX: Replace with 'repeat()'
+
+fun test(s: String) {
+    repeat(s.length) {}
+}

idea/tests/org/jetbrains/kotlin/idea/inspections/LocalInspectionTestGenerated.java

@@ -2557,6 +2557,11 @@ public class LocalInspectionTestGenerated extends AbstractLocalInspectionTest {
         public void testSequence() throws Exception {
             runTest("idea/testData/inspectionsLocal/forEachParameterNotUsed/sequence.kt");
         }
+
+        @TestMetadata("string.kt")
+        public void testString() throws Exception {
+            runTest("idea/testData/inspectionsLocal/forEachParameterNotUsed/string.kt");
+        }
     }
 
     @TestMetadata("idea/testData/inspectionsLocal/ImplicitNullableNothingType")