Fix zend_assign_to_typed_ref() implementation

There was some confusion going on here regarding the original
value vs the copied value.

I've dropped the needs_copy variable, because this code is not
inlined, so it would always be true anyway.

What we need to do is perform a move-assignment of the copied
value (in which case we don't care about performing the assignment
before destroying garbage), and destroying the original value
for the VAR/TMP cases. This is a bit complicated by the fact that
references are passed in via a separate ref variable, so we can't
just ptr_dtor the original variable.

Author: nikic

Zend/tests/type_declarations/typed_properties_107.phpt

@@ -0,0 +1,26 @@
+--TEST--
+Assigning stringable object to static string property
+--FILE--
+
+
+class Test1 {
+    public static $ref;
+}
+class Test2 {
+    public string $str = "str";
+}
+class Test3 {
+    public function __toString() {
+        $x = "foo";
+        return $x . "bar";
+    }
+}
+
+$test2 = new Test2;
+Test1::$ref =& $test2->str;
+Test1::$ref = new Test3;
+var_dump(Test1::$ref);
+
+?>
+--EXPECT--
+string(6) "foobar"

Zend/zend_execute.c

@@ -3168,45 +3168,41 @@ ZEND_API zend_bool ZEND_FASTCALL zend_verify_ref_assignable_zval(zend_reference
 	return 1;
 }
 
-ZEND_API zval* zend_assign_to_typed_ref(zval *variable_ptr, zval *value, zend_uchar value_type, zend_bool strict, zend_refcounted *ref)
-{
-	zend_bool need_copy = ZEND_CONST_COND(value_type & (IS_CONST|IS_CV), 1) ||
-			((value_type & IS_VAR) && UNEXPECTED(ref) && GC_REFCOUNT(ref) > 1);
-	zend_bool ret;
-	zval tmp;
-
-	if (need_copy) {
-		ZVAL_COPY(&tmp, value);
-		value = &tmp;
-	}
-	ret = zend_verify_ref_assignable_zval(Z_REF_P(variable_ptr), value, strict);
-	if (need_copy) {
-		Z_TRY_DELREF_P(value);
-	}
-	if (!ret) {
-		if (value_type & (IS_VAR|IS_TMP_VAR)) {
-			zval_ptr_dtor(value);
+static zend_always_inline void i_zval_ptr_dtor_noref(zval *zval_ptr) {
+	if (Z_REFCOUNTED_P(zval_ptr)) {
+		zend_refcounted *ref = Z_COUNTED_P(zval_ptr);
+		ZEND_ASSERT(Z_TYPE_P(zval_ptr) != IS_REFERENCE);
+		if (!GC_DELREF(ref)) {
+			rc_dtor_func(ref);
+		} else if (UNEXPECTED(GC_MAY_LEAK(ref))) {
+			gc_possible_root(ref);
 		}
-		return Z_REFVAL_P(variable_ptr);
 	}
+}
 
+ZEND_API zval* zend_assign_to_typed_ref(zval *variable_ptr, zval *orig_value, zend_uchar value_type, zend_bool strict, zend_refcounted *ref)
+{
+	zend_bool ret;
+	zval value;
+	ZVAL_COPY(&value, orig_value);
+	ret = zend_verify_ref_assignable_zval(Z_REF_P(variable_ptr), &value, strict);
 	variable_ptr = Z_REFVAL_P(variable_ptr);
-	if (EXPECTED(Z_REFCOUNTED_P(variable_ptr))) {
-		zend_refcounted *garbage = Z_COUNTED_P(variable_ptr);
-
-		zend_copy_to_variable(variable_ptr, value, value_type, ref);
-		if (GC_DELREF(garbage) == 0) {
-			rc_dtor_func(garbage);
-		} else { /* we need to split */
-			/* optimized version of GC_ZVAL_CHECK_POSSIBLE_ROOT(variable_ptr) */
-			if (UNEXPECTED(GC_MAY_LEAK(garbage))) {
-				gc_possible_root(garbage);
+	if (EXPECTED(ret)) {
+		i_zval_ptr_dtor_noref(variable_ptr);
+		ZVAL_COPY_VALUE(variable_ptr, &value);
+	} else {
+		zval_ptr_dtor_nogc(&value);
+	}
+	if (value_type & (IS_VAR|IS_TMP_VAR)) {
+		if (UNEXPECTED(ref)) {
+			if (UNEXPECTED(GC_DELREF(ref) == 0)) {
+				zval_ptr_dtor(orig_value);
+				efree_size(ref, sizeof(zend_reference));
 			}
+		} else {
+			i_zval_ptr_dtor_noref(orig_value);
 		}
-		return variable_ptr;
 	}
-
-	zend_copy_to_variable(variable_ptr, value, value_type, ref);
 	return variable_ptr;
 }