Fix FETCH_THIS result type

Author: iluuu1994

Zend/tests/gh20628.inc

@@ -0,0 +1,3 @@
+<?php
+
+$this->bar();

Zend/tests/gh20628.phpt

@@ -0,0 +1,22 @@
+--TEST--
+Invalid opcode for method call with FETCH_THIS
+--FILE--
+<?php
+
+class Foo {
+    public function bar() {
+        var_dump($this, __METHOD__);
+    }
+
+    public function test() {
+        require __DIR__ . '/gh20628.inc';
+    }
+}
+
+(new Foo)->test();
+
+?>
+--EXPECTF--
+object(Foo)#%d (0) {
+}
+string(8) "Foo::bar"

Zend/zend_compile.c

@@ -3153,7 +3153,11 @@ static zend_op *zend_delayed_compile_prop(znode *result, zend_ast *ast, uint32_t
 		if (this_guaranteed_exists()) {
 			obj_node.op_type = IS_UNUSED;
 		} else {
-			zend_emit_op(&obj_node, ZEND_FETCH_THIS, NULL, NULL);
+			opline = zend_emit_op(&obj_node, ZEND_FETCH_THIS, NULL, NULL);
+			if ((type == BP_VAR_R) || (type == BP_VAR_IS)) {
+				opline->result_type = IS_TMP_VAR;
+				obj_node.op_type = IS_TMP_VAR;
+			}
 		}
 		CG(active_op_array)->fn_flags |= ZEND_ACC_USES_THIS;
 
@@ -5479,7 +5483,7 @@ static void zend_compile_method_call(znode *result, zend_ast *ast, uint32_t type
 		if (this_guaranteed_exists()) {
 			obj_node.op_type = IS_UNUSED;
 		} else {
-			zend_emit_op(&obj_node, ZEND_FETCH_THIS, NULL, NULL);
+			zend_emit_op_tmp(&obj_node, ZEND_FETCH_THIS, NULL, NULL);
 		}
 		CG(active_op_array)->fn_flags |= ZEND_ACC_USES_THIS;