Always run kotlinc in <withKotlin/> Ant task

This change requires withKotlin to be run with Ant of version at least 1.8.2.

Some test data changed because now compileList contains both Java and Kotlin
sources

 #KT-7870 Fixed

ant/src/org/jetbrains/kotlin/ant/KotlinCompilerAdapter.java

@@ -16,13 +16,21 @@
 
 package org.jetbrains.kotlin.ant;
 
+import kotlin.KotlinPackage;
+import kotlin.jvm.functions.Function1;
 import org.apache.tools.ant.BuildException;
 import org.apache.tools.ant.taskdefs.Javac;
-import org.apache.tools.ant.taskdefs.compilers.DefaultCompilerAdapter;
 import org.apache.tools.ant.taskdefs.compilers.Javac13;
 import org.apache.tools.ant.types.Path;
+import org.jetbrains.annotations.NotNull;
+
+import java.io.File;
+import java.util.Arrays;
+import java.util.List;
+
+public class KotlinCompilerAdapter extends Javac13 {
+    private static final List<String> KOTLIN_EXTENSIONS = Arrays.asList("kt", "kts");
 
-public class KotlinCompilerAdapter extends DefaultCompilerAdapter {
     private Path externalAnnotations;
 
     public void setExternalAnnotations(Path externalAnnotations) {
@@ -36,27 +44,53 @@ public class KotlinCompilerAdapter extends DefaultCompilerAdapter {
         return externalAnnotations.createPath();
     }
 
+    @Override
+    public String[] getSupportedFileExtensions() {
+        List<String> result = KotlinPackage.plus(Arrays.asList(super.getSupportedFileExtensions()), KOTLIN_EXTENSIONS);
+        //noinspection SSBasedInspection
+        return result.toArray(new String[result.size()]);
+    }
+
     @Override
     public boolean execute() throws BuildException {
         Javac javac = getJavac();
 
-        Kotlin2JvmTask kotlinTask = new Kotlin2JvmTask();
-        kotlinTask.setOutput(javac.getDestdir());
+        Kotlin2JvmTask kotlinc = new Kotlin2JvmTask();
+        kotlinc.setOutput(javac.getDestdir());
 
         Path classpath = javac.getClasspath();
         if (classpath != null) {
-            kotlinTask.setClasspath(classpath);
+            kotlinc.setClasspath(classpath);
         }
 
-        kotlinTask.setSrc(javac.getSrcdir());
-        kotlinTask.setExternalAnnotations(externalAnnotations);
+        // We use the provided src dir instead of compileList, because the latter is insane:
+        // it is constructed only of sources which are newer than classes with the same name
+        kotlinc.setSrc(javac.getSrcdir());
 
-        kotlinTask.execute();
+        kotlinc.setExternalAnnotations(externalAnnotations);
+
+        kotlinc.execute();
 
         javac.log("Running javac...");
 
-        Javac13 javac13 = new Javac13();
-        javac13.setJavac(javac);
-        return javac13.execute();
+        // Javac13#execute passes everything in compileList to javac, which doesn't recognize .kt files
+        compileList = filterOutKotlinSources(compileList);
+
+        return compileList.length == 0 || super.execute();
+    }
+
+    @NotNull
+    private static File[] filterOutKotlinSources(@NotNull File[] files) {
+        List<File> nonKotlinSources = KotlinPackage.filterNot(files, new Function1<File, Boolean>() {
+            @Override
+            public Boolean invoke(File file) {
+                for (String extension : KOTLIN_EXTENSIONS) {
+                    if (file.getPath().endsWith("." + extension)) return true;
+                }
+                return false;
+            }
+        });
+
+        return nonKotlinSources.toArray(new File[nonKotlinSources.size()]);
     }
 }