GROOVY-12139: vararg-of-arrays argument wrapping fails under classic …

src/main/java/org/codehaus/groovy/reflection/ParameterTypes.java

@@ -20,6 +20,7 @@
 
 import org.codehaus.groovy.GroovyBugError;
 import org.codehaus.groovy.classgen.asm.util.TypeUtil;
+import org.codehaus.groovy.runtime.ArrayTypeUtils;
 import org.codehaus.groovy.runtime.MetaClassHelper;
 import org.codehaus.groovy.runtime.typehandling.DefaultTypeTransformation;
 import org.codehaus.groovy.runtime.wrappers.Wrapper;
@@ -271,18 +272,25 @@ private static Object[] fitToVargs(final Object[] arguments, final CachedClass[]
             args[aCount] = Array.newInstance(vaType, 0);
             return args;
         } else if (aCount == pCount) {
-            // the number of arguments is correct, but if the last argument
-            // is no array we have to wrap it in an array; if last argument
-            // is null, then we don't have to do anything
+            // the number of arguments is correct, but unless the last argument
+            // is null or usable as the varargs array itself — assignable, or
+            // an array of the same dimension whose elements the argument
+            // coercion below can convert (e.g. Integer[] for int...) — it is a
+            // single element and has to be wrapped in an array; being an array
+            // is not sufficient: a byte[] passed to a byte[]... parameter is
+            // an element, not the byte[][] varargs array (GROOVY-11182, GROOVY-12139)
             var lastArgument = getArgClass(arguments[aCount - 1]);
-            if (lastArgument != null && !lastArgument.isArray()) {
+            var varargsType = paramTypes[pCount - 1].getTheClass();
+            if (lastArgument == null || varargsType.isAssignableFrom(lastArgument)
+                    || (lastArgument.isArray()
+                        && ArrayTypeUtils.dimension(lastArgument) == ArrayTypeUtils.dimension(varargsType))) {
+                // we may have to box the argument!
+                return unwrappedArguments;
+            } else {
                 Object[] args = new Object[pCount];
                 System.arraycopy(unwrappedArguments, 0, args, 0, pCount - 1);
                 args[pCount-1] = makeCommonArray(unwrappedArguments, pCount - 1, vaType);
                 return args;
-            } else {
-                // we may have to box the argument!
-                return unwrappedArguments;
             }
         } else if (aCount > pCount) {
             // wrap tail arguments in an array

src/test/groovy/bugs/Groovy11182.groovy

@@ -18,21 +18,35 @@
  */
 package bugs
 
+import org.codehaus.groovy.control.CompilerConfiguration
 import org.junit.jupiter.api.Test
 
 import static groovy.test.GroovyAssert.assertScript
 
 final class Groovy11182 {
 
+    private static final String SCRIPT = '''
+        def foo(byte[]... byteArrays) {
+            assert byteArrays.length == 1
+            assert byteArrays[0].length == 4
+        }
+
+        foo("test".bytes)
+    '''
+
     @Test
     void testVariadicPrimitiveArray() {
-        assertScript '''
-            def foo(byte[]... byteArrays) {
-                assert byteArrays.length == 1
-                assert byteArrays[0].length == 4
-            }
+        assertScript SCRIPT
+    }
 
-            foo("test".bytes)
-        '''
+    // GROOVY-12139: the classic call-site path dispatches through
+    // MetaMethod#doMethodInvoke, whose varargs correction used to pass any
+    // trailing array through unwrapped instead of wrapping it when it is not
+    // assignable to the varargs parameter type (byte[] into byte[][])
+    @Test
+    void testVariadicPrimitiveArrayClassic() {
+        def config = new CompilerConfiguration()
+        config.optimizationOptions.indy = false
+        new GroovyShell(config).evaluate SCRIPT
     }
 }