Fix bug where return type checking was overzealous and interfered with generators

Zend/tests/generators/generator_return_without_value.phpt

@@ -0,0 +1,25 @@
+--TEST--
+Generators can return without values
+--FILE--
+<?php
+
+function gen() {
+    yield;
+    return;
+}
+
+function gen2() {
+    yield;
+    return null;
+}
+
+var_dump(gen());
+
+var_dump(gen2());
+
+?>
+--EXPECTF--
+object(Generator)#%d (0) {
+}
+object(Generator)#%d (0) {
+}

Zend/zend_compile.c

@@ -3268,7 +3268,8 @@ void zend_compile_return(zend_ast *ast) /* {{{ */
 		opline->op1.var = CG(context).fast_call_var;
 	}
 
-	if (CG(active_op_array)->fn_flags & ZEND_ACC_HAS_RETURN_TYPE) {
+    // Generator return types are handled separately
+	if (!(CG(active_op_array)->fn_flags & ZEND_ACC_GENERATOR) && CG(active_op_array)->fn_flags & ZEND_ACC_HAS_RETURN_TYPE) {
 		zend_arg_info *arg_info = CG(active_op_array)->arg_info - 1;
 
 		/* for scalar, weak return types, the value may be casted