8261785: Calling "main" method in anonymous nested class crashes the JVM

src/java.base/macosx/native/libjli/java_md_macosx.m

@@ -827,7 +827,7 @@ static void MacOSXStartup(int argc, char *argv[]) {
     NULL_CHECK(getCanonicalNameMID = (*env)->GetMethodID(env, classClass, "getCanonicalName", "()Ljava/lang/String;"));
 
     jstring mainClassString = (*env)->CallObjectMethod(env, mainClass, getCanonicalNameMID);
-    if ((*env)->ExceptionCheck(env)) {
+    if ((*env)->ExceptionCheck(env) || NULL == mainClassString) {
         /*
          * Clears all errors caused by getCanonicalName() on the mainclass and
          * leaves the JAVA_MAIN_CLASS__<pid> empty.

test/jdk/tools/launcher/8261785/CrashTheJVM.java

@@ -0,0 +1,72 @@
+/*
+ * Copyright (c) 2021, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+import java.io.IOException;
+
+public class CrashTheJVM {
+    public static void main(String... args) throws IOException {
+        System.out.println("Fine 1: from the outer class");
+
+        new Object() {
+            public static void main(String... args) throws IOException {
+                System.out.println("Crash Before Fix 1: from anonymous nested class");
+            }
+        };
+        class LocalNestedClass {
+            public static void main(String... args) throws IOException {
+                System.out.println("Crash Before Fix 2: from local nested class");
+            }
+        }
+    }
+
+    public void fromMethod() {
+        new Object() {
+            public static void main(String... args) throws IOException {
+                System.out.println("Crash Before Fix 3: from local anonymous class");
+            }
+        };
+        class LocalInnerClass {
+            public static void main(String... args) throws IOException {
+                System.out.println("Crash Before Fix 4: from local inner class");
+            }
+        }
+    }
+
+    public class InnerClass {
+        public static void main(String... args) throws IOException {
+            System.out.println("Fine 2: from inner class");
+        }
+    }
+
+    public static class NestedClass {
+        public static void main(String... args) throws IOException {
+            System.out.println("Fine 3: from nested class");
+        }
+    }
+
+    Object foo = new Object() {
+        public static void main(String... args) throws IOException {
+            System.out.println("Anonymous inner class");
+        }
+    };
+}

test/jdk/tools/launcher/8261785/Test8261785.java

@@ -0,0 +1,70 @@
+/*
+ * Copyright (c) 2021, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import org.testng.annotations.Test;
+import static org.testng.Assert.assertEquals;
+import static org.testng.Assert.assertTrue;
+
+/*
+ * @test
+ * @bug 8261785
+ * @summary Test static main methods in anonymous/local class won't cause launcher crash
+ * @modules jdk.compiler jdk.zipfs
+ * @compile ../TestHelper.java
+ * @run testng Test8261785
+ */
+public class Test8261785 {
+    private final Path inputDir;
+
+    public Test8261785() {
+        inputDir = Paths.get(System.getProperty("test.src", "."));
+    }
+
+    public void compile() {
+        Path file = inputDir.resolve("CrashTheJVM.java");
+        TestHelper.compile("-d", ".", file.toAbsolutePath().toString());
+    }
+
+    @Test
+    public void run() throws IOException {
+        System.out.println("Current folder: " + Paths.get(".").toAbsolutePath().toString());
+        compile();
+        String[] clz = Files.list(Paths.get("."))
+            .peek(p -> System.out.println("Found " + p.toString()))
+            .map(Path::getFileName)
+            .map(Path::toString)
+            .filter(f -> f.endsWith(".class"))
+            .map(f -> f.substring(0, f.length() - 6))
+            .toArray(String[]::new);
+        assertEquals(clz.length, 8);
+        for (String f: clz) {
+            System.out.println("Running class " + f);
+            var result = TestHelper.doExec(TestHelper.javaCmd, "-cp", ".", f);
+            assertTrue(result.isOK());
+        };
+    }
+}