[php] Add php:allowdynamicproperties feature

This follows PHP 8.2 deprecating dynamic features.

The new feature also provides a clean way to fix the remaining PHP
test case failure under PHP 8.2.

CHANGES.current

@@ -7,6 +7,29 @@ the issue number to the end of the URL: https://github.com/swig/swig/issues/
 Version 4.1.0 (in progress)
 ===========================
 
+2022-09-29: olly
+	    [PHP] Dynamic class properties are no longer supported by default.
+
+	    Historically PHP has supported dynamic class properties and SWIG
+	    has implemented them too (because we implement the magic __get(),
+	    __set() and __isset() methods we need to include explicit
+	    handling).
+
+	    PHP 8.2 deprecates dynamic class properties - initially they'll
+	    warn, and apparently they'll not work by default in PHP 9.0:
+	    https://wiki.php.net/rfc/deprecate_dynamic_properties
+
+	    In PHP code dynamic properties can be enabled for a class by
+	    marking that class with the attribute `#[AllowDynamicProperties]`.
+
+	    To follow this PHP change, in SWIG you now need to specify
+	    `%feature("php:allowdynamicproperties", 1) Foo;` (or
+	    `%feature("php:allowdynamicproperties", 1)` to enable it for
+	    all wrapped classes).  Unknown features are ignored, so you can add
+	    it unconditionally and it'll work with older SWIG too.
+
+	    *** POTENTIAL INCOMPATIBILITY ***
+
 2022-09-19: wsfulton
             #1484 Fixes for class inheritance with the same name in different namespaces
             such as:

Doc/Manual/Php.html

@@ -30,6 +30,7 @@
 <li><a href="#Php_nn2_6_3">Static Member Variables</a>
 <li><a href="#Php_nn2_6_4">Static Member Functions</a>
 <li><a href="#Php_nn2_6_5">Specifying Implemented Interfaces</a>
+<li><a href="#Php_nn2_6_6">Dynamic Properties</a>
 </ul>
 <li><a href="#Php_nn2_7">PHP Pragmas, Startup and Shutdown code</a>
 </ul>
@@ -843,6 +844,53 @@ so:
 If there are multiple interfaces, just list them separated by commas.
 </p>
 
+
+<H4><a name="Php_nn2_6_6">32.2.6.6 Dynamic Properties</a></H4>
+
+
+<p>
+Historically PHP has supported dynamic class properties and SWIG
+has implemented them too (because we implement the magic <tt>__get()</tt>,
+<tt>__set()</tt> and <tt>__isset()</tt> methods we need to include explicit
+handling).
+</p>
+
+<p>
+PHP 8.2 <a
+href="https://wiki.php.net/rfc/deprecate_dynamic_properties">deprecates
+dynamic class properties</a> - initially they'll warn, and apparently they'll
+not work by default in PHP 9.0.
+</p>
+
+<p>
+In PHP code dynamic properties can be enabled for a class by
+marking that class with the attribute <tt>#[AllowDynamicProperties]</tt>.
+</p>
+	
+<p>
+To follow this PHP change, as of SWIG 4.1.0 you now need enable dynamic
+properties for any classes you want to support them.  To enable for class
+<tt>Foo</tt>:
+</p>
+
+<div class="code"><pre>
+%feature("php:allowdynamicproperties", 1) Foo;
+</pre></div>
+
+<p>
+or to enable them for all wrapped classes:
+</p>
+
+<div class="code"><pre>
+%feature("php:allowdynamicproperties", 1);
+</pre></div>
+
+<p>
+Note that unknown features are ignored, so you can add use these
+unconditionally in your interface file and it'll work with older SWIG too.
+</p>
+
+
 <H3><a name="Php_nn2_7">32.2.7 PHP Pragmas, Startup and Shutdown code</a></H3>
 
 

Examples/test-suite/cpp_basic.i

@@ -4,6 +4,8 @@
 
 %warnfilter(SWIGWARN_RUBY_WRONG_NAME) global_cint;       /* Ruby, wrong constant name */
 
+%feature("php:allowdynamicproperties", 1) Foo; /* Allow PHP-specific custom property testing in _runme.php */
+
 %module cpp_basic
 
 %newobject Bar::testFoo;

Source/Modules/php.cxx

@@ -1056,12 +1056,12 @@ public:
 		      "  if (director) director->swig_disown();\n",
 		      "}\n", NIL);
     }
-    Printf(f->code, "} else {\n");
     if (swig_base) {
-      Printf(f->code, "PHP_MN(%s%s___set)(INTERNAL_FUNCTION_PARAM_PASSTHRU);\n}\n", prefix, swig_base);
-    } else {
-      Printf(f->code, "add_property_zval_ex(ZEND_THIS, ZSTR_VAL(arg2), ZSTR_LEN(arg2), &args[1]);\n}\n");
+      Printf(f->code, "} else {\nPHP_MN(%s%s___set)(INTERNAL_FUNCTION_PARAM_PASSTHRU);\n", prefix, swig_base);
+    } else if (Getattr(class_node, "feature:php:allowdynamicproperties")) {
+      Printf(f->code, "} else {\nadd_property_zval_ex(ZEND_THIS, ZSTR_VAL(arg2), ZSTR_LEN(arg2), &args[1]);\n");
     }
+    Printf(f->code, "}\n");
 
     Printf(f->code, "fail:\n");
     Printf(f->code, "return;\n");
@@ -1777,6 +1777,15 @@ public:
     if (Getattr(n, "abstracts") && !GetFlag(n, "feature:notabstract")) {
       Printf(s_oinit, "  SWIG_Php_ce_%s->ce_flags |= ZEND_ACC_EXPLICIT_ABSTRACT_CLASS;\n", class_name);
     }
+    if (Getattr(n, "feature:php:allowdynamicproperties")) {
+      Append(s_oinit, "#ifdef ZEND_ACC_ALLOW_DYNAMIC_PROPERTIES\n");
+      Printf(s_oinit, "  SWIG_Php_ce_%s->ce_flags |= ZEND_ACC_ALLOW_DYNAMIC_PROPERTIES;\n", class_name);
+      Append(s_oinit, "#endif\n");
+    } else {
+      Append(s_oinit, "#ifdef ZEND_ACC_NO_DYNAMIC_PROPERTIES\n");
+      Printf(s_oinit, "  SWIG_Php_ce_%s->ce_flags |= ZEND_ACC_NO_DYNAMIC_PROPERTIES;\n", class_name);
+      Append(s_oinit, "#endif\n");
+    }
     String *swig_wrapped = swig_wrapped_interface_ce();
     Printv(s_oinit, "  zend_do_implement_interface(SWIG_Php_ce_", class_name, ", &", swig_wrapped, ");\n", NIL);