FIX: equality of objects with hidden values

resolves: Oldes/Rebol-issues#1778

Author: Oldes

src/core/t-object.c

@@ -62,6 +62,8 @@ static REBOOL Equal_Object(REBVAL *val, REBVAL *arg)
 
 	// Compare each entry:
 	for (n = 1; n < (REBINT)(f1->tail); n++) {
+		if (VAL_HIDDEN(BLK_SKIP(w1, n))) return VAL_HIDDEN(BLK_SKIP(w2, n));
+		if (VAL_HIDDEN(BLK_SKIP(w2, n))) return VAL_HIDDEN(BLK_SKIP(w1, n));
 		if (Cmp_Value(BLK_SKIP(w1, n), BLK_SKIP(w2, n), FALSE)) return FALSE;
 		// Use Compare_Values();
 		if (Cmp_Value(BLK_SKIP(f1, n), BLK_SKIP(f2, n), FALSE)) return FALSE;

src/tests/units/protect-test.r3

@@ -166,6 +166,14 @@ Rebol [
 		a: "123"
 		--assert all [error? e: try [protect/hide :a] e/id = 'bad-refines]
 
+	--test-- "compare objects with hidden values"
+	;@@ https://github.com/Oldes/Rebol-issues/issues/1778
+		--assert equal? context [a: 1 protect/hide 'a] context [a: 2 protect/hide 'a]
+		--assert equal? context [a: 1 protect/hide 'a] context [a: 1 protect/hide 'a]
+		--assert equal? context [a: 1 protect/hide 'a] context [b: 1 protect/hide 'b]
+		--assert not equal? context [a: 1 protect/hide 'a] context [a: 1]
+		--assert not equal? context [a: 1] context [a: 1 protect/hide 'a]
+		--assert not equal? context [a: 1 protect/hide 'a] context []
 
 ===end-group===