Disallow asymmetric visibility on static properties

This check was forgotten in the original implementation. Relaxing this
restriction shouldn't be hard, but needs some work. We either need to prevent
merging of cache slots for R/RW/W, or we need to introduce an additional check
when writing to the property indirectly. This check is currently present only
for direct writes.

Author: iluuu1994

Zend/tests/asymmetric_visibility/static_props.phpt

@@ -0,0 +1,12 @@
+--TEST--
+Asymmetric visibility on static props
+--FILE--
+<?php
+
+class C {
+    public private(set) static int $prop;
+}
+
+?>
+--EXPECTF--
+Fatal error: Static property may not have asymmetric visibility in %s on line %d

Zend/zend_compile.c

@@ -8598,6 +8598,10 @@ static void zend_compile_prop_decl(zend_ast *ast, zend_ast *type_ast, uint32_t f
 		zend_error_noreturn(E_COMPILE_ERROR, "Property cannot be both final and private");
 	}
 
+	if ((flags & ZEND_ACC_STATIC) && (flags & ZEND_ACC_PPP_SET_MASK)) {
+		zend_error_noreturn(E_COMPILE_ERROR, "Static property may not have asymmetric visibility");
+	}
+
 	if (ce->ce_flags & ZEND_ACC_INTERFACE) {
 		if (flags & ZEND_ACC_FINAL) {
 			zend_error_noreturn(E_COMPILE_ERROR, "Property in interface cannot be final");