Support JDK 16

.github/workflows/ci.yml

@@ -20,7 +20,7 @@ jobs:
         runs-on: ubuntu-latest
         strategy:
             matrix:
-                jdk: [11, 15]
+                jdk: [11, 15, 16]
         steps:
             - uses: actions/checkout@v2
             - uses: actions/cache@v2.1.4

build.gradle.kts

@@ -3,7 +3,7 @@ plugins {
 	id("java")
 	id("java-library")
 	id("maven-publish")
-	id("dev.minco.gradle.defaults-plugin") version "0.2.8"
+	id("dev.minco.gradle.defaults-plugin") version "0.2.26"
 	id("org.shipkit.shipkit-auto-version") version "1.1.1"
 	id("org.shipkit.shipkit-changelog") version "1.1.4"
 	id("org.shipkit.shipkit-github-release") version "1.1.4"

gradle.properties

@@ -0,0 +1,6 @@
+# The exports are needed due to https://github.com/diffplug/spotless/issues/834
+org.gradle.jvmargs=--add-exports jdk.compiler/com.sun.tools.javac.api=ALL-UNNAMED \
+  --add-exports jdk.compiler/com.sun.tools.javac.file=ALL-UNNAMED \
+  --add-exports jdk.compiler/com.sun.tools.javac.parser=ALL-UNNAMED \
+  --add-exports jdk.compiler/com.sun.tools.javac.tree=ALL-UNNAMED \
+  --add-exports jdk.compiler/com.sun.tools.javac.util=ALL-UNNAMED

src/main/java/dev/minco/javatransformer/internal/util/DefineClass.java

@@ -10,7 +10,7 @@
 import lombok.SneakyThrows;
 
 public final class DefineClass {
-	private static final MethodHandles.Lookup $L = UnsafeAccess.IMPL_LOOKUP;
+	private static final MethodHandles.Lookup $L = LookupAccess.privateLookupFor(ClassLoader.class);
 	private static final ProtectionDomain PROTECTION_DOMAIN = AccessController.doPrivileged((PrivilegedAction<ProtectionDomain>) DefineClass.class::getProtectionDomain);
 	private static final MethodHandle defineClassHandle = getDefineClassHandle();
 

src/main/java/dev/minco/javatransformer/internal/util/LookupAccess.java

@@ -0,0 +1,36 @@
+package dev.minco.javatransformer.internal.util;
+
+import java.lang.invoke.MethodHandles;
+
+import lombok.SneakyThrows;
+import lombok.val;
+
+public class LookupAccess {
+	private static final MethodHandles.Lookup IMPL_LOOKUP;
+
+	@SneakyThrows
+	public static MethodHandles.Lookup privateLookupFor(Class<?> clazz) {
+		if (IMPL_LOOKUP != null) {
+			return IMPL_LOOKUP;
+		}
+
+		MethodHandles.Lookup lookup = MethodHandles.lookup();
+
+		Object privateLookupIn = MethodHandles.class.getMethod("privateLookupIn", Class.class, MethodHandles.Lookup.class)
+			.invoke(null, clazz, lookup);
+		return (MethodHandles.Lookup) privateLookupIn;
+	}
+
+	static {
+		MethodHandles.Lookup lookup = null;
+		try {
+			val field = MethodHandles.Lookup.class.getDeclaredField("IMPL_LOOKUP");
+			field.setAccessible(true);
+			lookup = (MethodHandles.Lookup) field.get(null);
+		} catch (Throwable t) {
+			System.err.println("Failed to get MethodHandles.Lookup.IMPL_LOOKUP");
+			t.printStackTrace();
+		}
+		IMPL_LOOKUP = lookup;
+	}
+}