Replace File.relativePath from stdlib with File.descendantRelativeTo in fileUtils.

IO utils: cleanup java usages.

compiler/cli/src/org/jetbrains/kotlin/cli/common/messages/MessageRenderer.java

@@ -19,6 +19,7 @@ package org.jetbrains.kotlin.cli.common.messages;
 import kotlin.io.FilesKt;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
+import org.jetbrains.kotlin.utils.fileUtils.FileUtilsKt;
 
 import java.io.File;
 
@@ -43,13 +44,14 @@ public interface MessageRenderer {
     };
 
     MessageRenderer PLAIN_RELATIVE_PATHS = new PlainTextMessageRenderer() {
+        @NotNull
         private final File cwd = new File(".").getAbsoluteFile();
 
         @Nullable
         @Override
         protected String getPath(@NotNull CompilerMessageLocation location) {
             String path = location.getPath();
-            return cwd == null || path == null ? path : FilesKt.relativePath(cwd, new File(path));
+            return path == null ? path : FileUtilsKt.descendantRelativeTo(new File(path), cwd).getPath();
         }
     };
 

compiler/cli/src/org/jetbrains/kotlin/cli/jvm/compiler/CompileEnvironmentUtil.java

@@ -30,6 +30,7 @@ import com.intellij.psi.PsiManager;
 import kotlin.Unit;
 import kotlin.io.FilesKt;
 import kotlin.jvm.functions.Function1;
+import kotlin.sequences.SequencesKt;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 import org.jetbrains.kotlin.backend.common.output.OutputFile;
@@ -162,7 +163,7 @@ public class CompileEnvironmentUtil {
                 continue;
             }
 
-            FilesKt.recurse(new File(sourceRootPath), new Function1<File, Unit>() {
+            SequencesKt.forEach(FilesKt.walkTopDown(new File(sourceRootPath)), new Function1<File, Unit>() {
                 @Override
                 public Unit invoke(File file) {
                     if (file.isFile()) {

compiler/util/src/org/jetbrains/kotlin/utils/fileUtils.kt

@@ -31,4 +31,24 @@ fun File.withReplacedExtensionOrNull(oldExt: String, newExt: String): File? {
     }
 
     return null
+}
+
+/**
+ * Calculates the relative path to this file from [base] file.
+ * Note that the [base] file is treated as a directory.
+ *
+ * If this file matches the [base] directory an empty path is returned.
+ * If this file does not belong to the [base] directory, it is returned unchanged.
+ */
+public fun File.descendantRelativeTo(base: File): File {
+    val prefix = base.canonicalPath
+    val answer = this.canonicalPath
+    return if (answer.startsWith(prefix)) {
+        val prefixSize = prefix.length
+        if (answer.length > prefixSize) {
+            File(answer.substring(prefixSize + 1))
+        } else File("")
+    } else {
+        this
+    }
 }