Code cleanup: get rid of _ (mostly renamed to arg)

compiler/cli/src/org/jetbrains/kotlin/cli/jvm/compiler/JvmCliVirtualFileFinder.kt

@@ -24,7 +24,7 @@ public class JvmCliVirtualFileFinder(private val index: JvmDependenciesIndex) :
 
     override fun findVirtualFileWithHeader(classId: ClassId): VirtualFile? {
         val classFileName = classId.getRelativeClassName().asString().replace('.', '$')
-        return index.findClass(classId, acceptedRootTypes = JavaRoot.OnlyBinary) { dir, _ ->
+        return index.findClass(classId, acceptedRootTypes = JavaRoot.OnlyBinary) { dir, rootType ->
             dir.findChild("$classFileName.class")?.let {
                 if (it.isValid()) it else null
             }

compiler/cli/src/org/jetbrains/kotlin/cli/jvm/compiler/KotlinCliJavaFileManagerImpl.kt

@@ -87,7 +87,7 @@ public class KotlinCliJavaFileManagerImpl(private val myPsiManager: PsiManager)
     override fun findPackage(packageName: String): PsiPackage? {
         var found = false
         val packageFqName = packageName.toSafeFqName() ?: return null
-        index.traverseDirectoriesInPackage(packageFqName) { _, __ ->
+        index.traverseDirectoriesInPackage(packageFqName) { dir, rootType ->
             found = true
             //abort on first found
             false

compiler/frontend/src/org/jetbrains/kotlin/types/expressions/FakeCallResolver.kt

@@ -81,7 +81,7 @@ public class FakeCallResolver(
         val fakeBindingTrace = context.replaceBindingTrace(fakeTrace)
 
         return makeAndResolveFakeCallInContext(receiver, fakeBindingTrace, valueArguments, name, callElement) { fake ->
-            fakeTrace.commit({ _, key ->
+            fakeTrace.commit({ slice, key ->
                 // excluding all entries related to fake expression
                 key != fake
             }, true)