Update Kotlin to 2.0 (#900)

- update Kotlin from 1.7.10 to 2.0.21
  - Kotlin 1.6 dependencies in Gradle lock files are expected because kotlinc,
    which is also used by some tests, internally uses some 1.6 dependencies
    for backwards compatibility reasons.
- update kotlinx-html and kotlinx-serialization
- adapt Kotlin code where necessary
- use Kotlin stdlib Path APIs where possible
- fix IntelliJ Kotlin inspection warnings
- reformat code with `./gradlew spotlessApply`
  - ktfmt adds lots of trailing commas
- Add workaround to fix IntelliJ "unresolved reference" errors

pkl-gradle/src/test/kotlin/org/pkl/gradle/AbstractTest.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2025 Apple Inc. and the Pkl project authors. All rights reserved.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,14 +17,14 @@ package org.pkl.gradle
 
 import java.net.URI
 import java.nio.file.Path
+import kotlin.io.path.createParentDirectories
+import kotlin.io.path.writeText
 import org.assertj.core.api.Assertions.assertThat
 import org.gradle.testkit.runner.BuildResult
 import org.gradle.testkit.runner.GradleRunner
 import org.gradle.testkit.runner.UnexpectedBuildFailure
 import org.junit.jupiter.api.io.TempDir
-import org.pkl.commons.createParentDirectories
 import org.pkl.commons.readString
-import org.pkl.commons.writeString
 
 abstract class AbstractTest {
   private val gradleVersion: String? = System.getProperty("testGradleVersion")
@@ -57,10 +57,10 @@ abstract class AbstractTest {
   }
 
   protected fun writeFile(fileName: String, contents: String): Path {
-    return testProjectDir
-      .resolve(fileName)
-      .apply { createParentDirectories() }
-      .writeString(contents.trimIndent())
+    return testProjectDir.resolve(fileName).apply {
+      createParentDirectories()
+      writeText(contents.trimIndent())
+    }
   }
 
   protected fun checkFileContents(file: Path, contents: String) {

pkl-gradle/src/test/kotlin/org/pkl/gradle/JavaCodeGeneratorsTest.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2025 Apple Inc. and the Pkl project authors. All rights reserved.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -31,7 +31,7 @@ class JavaCodeGeneratorsTest : AbstractTest() {
     val baseDir = testProjectDir.resolve("build/generated/java/foo/bar")
     val moduleFile = baseDir.resolve("Mod.java")
 
-    assertThat(baseDir.listDirectoryEntries().count()).isEqualTo(1)
+    assertThat(baseDir.listDirectoryEntries().size).isEqualTo(1)
     assertThat(moduleFile).exists()
 
     val text = moduleFile.readText()
@@ -44,7 +44,7 @@ class JavaCodeGeneratorsTest : AbstractTest() {
       """
       |public final class Mod {
       |  public final @Nonnull Object other;
-    """
+    """,
     )
 
     checkTextContains(
@@ -54,7 +54,7 @@ class JavaCodeGeneratorsTest : AbstractTest() {
       |    public final @Nonnull String name;
       |
       |    public final @Nonnull List<Address> addresses;
-    """
+    """,
     )
 
     checkTextContains(
@@ -64,7 +64,7 @@ class JavaCodeGeneratorsTest : AbstractTest() {
       |    public final @Nonnull String street;
       |
       |    public final long zip;
-    """
+    """,
     )
   }
 
@@ -100,7 +100,7 @@ class JavaCodeGeneratorsTest : AbstractTest() {
           }
         }
       }
-    """
+    """,
     )
 
     val result = runTask("evalTest", true)
@@ -139,7 +139,7 @@ class JavaCodeGeneratorsTest : AbstractTest() {
           }
         }
       }
-    """
+    """,
     )
   }
 
@@ -160,7 +160,7 @@ class JavaCodeGeneratorsTest : AbstractTest() {
         }
   
         other = 42
-      """
+      """,
     )
   }
 }

pkl-gradle/src/test/kotlin/org/pkl/gradle/KotlinCodeGeneratorsTest.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2025 Apple Inc. and the Pkl project authors. All rights reserved.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -31,7 +31,7 @@ class KotlinCodeGeneratorsTest : AbstractTest() {
     val baseDir = testProjectDir.resolve("build/generated/kotlin/foo/bar")
     val kotlinFile = baseDir.resolve("Mod.kt")
 
-    assertThat(baseDir.listDirectoryEntries().count()).isEqualTo(1)
+    assertThat(baseDir.listDirectoryEntries().size).isEqualTo(1)
     assertThat(kotlinFile).exists()
 
     val text = kotlinFile.readText()
@@ -39,11 +39,14 @@ class KotlinCodeGeneratorsTest : AbstractTest() {
     // shading must not affect generated code
     assertThat(text).doesNotContain("org.pkl.thirdparty")
 
-    checkTextContains(text, """
+    checkTextContains(
+      text,
+      """
       |data class Mod(
       |  val other: Any?
       |)
-    """)
+    """,
+    )
 
     checkTextContains(
       text,
@@ -52,7 +55,7 @@ class KotlinCodeGeneratorsTest : AbstractTest() {
       |    val name: String,
       |    val addresses: List<Address>
       |  )
-    """
+    """,
     )
 
     checkTextContains(
@@ -62,7 +65,7 @@ class KotlinCodeGeneratorsTest : AbstractTest() {
       |    open val street: String,
       |    open val zip: Long
       |  )
-    """
+    """,
     )
   }
 
@@ -97,7 +100,7 @@ class KotlinCodeGeneratorsTest : AbstractTest() {
           }
         }
       }
-    """
+    """,
     )
 
     val result = runTask("evalTest", true)
@@ -148,7 +151,7 @@ class KotlinCodeGeneratorsTest : AbstractTest() {
           }
         }
       }
-    """
+    """,
     )
   }
 
@@ -170,7 +173,7 @@ class KotlinCodeGeneratorsTest : AbstractTest() {
       }
 
       other = 42
-    """
+    """,
     )
   }
 }