Reflection: show the type of object constants used as default properties

When a property default is based on a global constant, show the type of the
default. Previously, `format_default_value()` assumed that non-scalar and
non-array defaults were always going to be `IS_CONSTANT_AST` pointers, and when
the AST expression had been evaluated and produced an object, depending on when
the `ReflectionClass` or `ReflectionProperty` instance had been created, the
default was shown as one of `callable`, `__CLASS__`, or `...`.

Instead, if the default value is an object (`IS_OBJECT`), show the type of that
object.

Add test cases for each of the `callable`, `__CLASS__`, and `...` cases to
confirm that they all now properly show the name of the constant.

Closes gh-15902

Author: DanielEScherzer

ext/reflection/php_reflection.c

@@ -682,6 +682,11 @@ static int format_default_value(smart_str *str, zval *value) {
 			format_default_value(str, zv);
 		} ZEND_HASH_FOREACH_END();
 		smart_str_appendc(str, ']');
+	} else if (Z_TYPE_P(value) == IS_OBJECT) {
+		// Show a consistent output with the type of the object, GH-15902
+		smart_str_appends(str, "object(");
+		smart_str_append(str, Z_OBJCE_P(value)->name);
+		smart_str_appends(str, ")");
 	} else {
 		ZEND_ASSERT(Z_TYPE_P(value) == IS_CONSTANT_AST);
 		zend_string *ast_str = zend_ast_export("", Z_ASTVAL_P(value), "");

ext/reflection/tests/gh15902/ReflectionClass-callable.phpt

@@ -0,0 +1,36 @@
+--TEST--
+ReflectionClass object default property - used to say "callable"
+--FILE--
+<?php
+
+class C {
+	public stdClass $a = FOO;
+}
+define('FOO', new stdClass);
+
+new C;
+
+$reflector = new ReflectionClass(C::class);
+var_dump( (string)$reflector );
+?>
+--EXPECTF--
+string(%d) "Class [ <user> class C ] {
+  @@ %sReflectionClass-callable.php %d-%d
+
+  - Constants [0] {
+  }
+
+  - Static properties [0] {
+  }
+
+  - Static methods [0] {
+  }
+
+  - Properties [1] {
+    Property [ public stdClass $a = object(stdClass) ]
+  }
+
+  - Methods [0] {
+  }
+}
+"

ext/reflection/tests/gh15902/ReflectionClass-class.phpt

@@ -0,0 +1,37 @@
+--TEST--
+ReflectionClass object default property - used to say "__CLASS__"
+--FILE--
+<?php
+
+class C {
+	public stdClass $a = FOO;
+}
+$reflector = new ReflectionClass(C::class);
+
+define('FOO', new stdClass);
+new C;
+
+var_dump( (string)$reflector );
+
+?>
+--EXPECTF--
+string(%d) "Class [ <user> class C ] {
+  @@ %sReflectionClass-class.php %d-%d
+
+  - Constants [0] {
+  }
+
+  - Static properties [0] {
+  }
+
+  - Static methods [0] {
+  }
+
+  - Properties [1] {
+    Property [ public stdClass $a = object(stdClass) ]
+  }
+
+  - Methods [0] {
+  }
+}
+"

ext/reflection/tests/gh15902/ReflectionClass-dots.phpt

@@ -0,0 +1,39 @@
+--TEST--
+ReflectionClass object default property - used to say "..."
+--FILE--
+<?php
+
+class C {
+	public stdClass $a = FOO;
+}
+$reflector = new ReflectionClass(C::class);
+$c = $reflector->newLazyGhost(function () {});
+
+define('FOO', new stdClass);
+
+$c->a;
+
+var_dump( (string)$reflector );
+
+?>
+--EXPECTF--
+string(%d) "Class [ <user> class C ] {
+  @@ %sReflectionClass-dots.php %d-%d
+
+  - Constants [0] {
+  }
+
+  - Static properties [0] {
+  }
+
+  - Static methods [0] {
+  }
+
+  - Properties [1] {
+    Property [ public stdClass $a = object(stdClass) ]
+  }
+
+  - Methods [0] {
+  }
+}
+"

ext/reflection/tests/gh15902/ReflectionProperty-callable.phpt

@@ -0,0 +1,19 @@
+--TEST--
+ReflectionProperty object default - used to say "callable"
+--FILE--
+<?php
+
+class C {
+	public stdClass $a = FOO;
+}
+define('FOO', new stdClass);
+
+new C;
+
+$reflector = new ReflectionProperty(C::class, 'a');
+var_dump( (string)$reflector );
+
+?>
+--EXPECTF--
+string(%d) "Property [ public stdClass $a = object(stdClass) ]
+"

ext/reflection/tests/gh15902/ReflectionProperty-class.phpt

@@ -0,0 +1,19 @@
+--TEST--
+ReflectionProperty object default - used to say "__CLASS__"
+--FILE--
+<?php
+
+class C {
+	public stdClass $a = FOO;
+}
+$reflector = new ReflectionProperty(C::class, 'a');
+
+define('FOO', new stdClass);
+new C;
+
+var_dump( (string)$reflector );
+
+?>
+--EXPECTF--
+string(%d) "Property [ public stdClass $a = object(stdClass) ]
+"

ext/reflection/tests/gh15902/ReflectionProperty-dots.phpt

@@ -0,0 +1,22 @@
+--TEST--
+ReflectionProperty object default - used to say "..."
+--FILE--
+<?php
+
+class C {
+	public stdClass $a = FOO;
+}
+$reflector = new ReflectionProperty(C::class, 'a');
+$lazyFactory = new ReflectionClass(C::class);
+$c = $lazyFactory->newLazyGhost(function () {});
+
+define('FOO', new stdClass);
+
+$c->a;
+
+var_dump( (string)$reflector );
+
+?>
+--EXPECTF--
+string(%d) "Property [ public stdClass $a = object(stdClass) ]
+"