Fix assertion failure when var_dump'ing void FFI result (php#10568)

Author: ndossche

ext/ffi/ffi.c

@@ -1982,6 +1982,8 @@ static HashTable *zend_ffi_cdata_get_debug_info(zend_object *obj, int *is_temp)
 	}
 
 	switch (type->kind) {
+		case ZEND_FFI_TYPE_VOID:
+			return NULL;
 		case ZEND_FFI_TYPE_BOOL:
 		case ZEND_FFI_TYPE_CHAR:
 		case ZEND_FFI_TYPE_ENUM:

ext/ffi/tests/gh10568.phpt

@@ -0,0 +1,25 @@
+--TEST--
+GH-10568 (Assertion failure when var_dump'ing void FFI result)
+--EXTENSIONS--
+ffi
+--SKIPIF--
+<?php
+try {
+    $libc = FFI::cdef("void strlen(const char *s);", "libc.so.6");
+} catch (Throwable $_) {
+    die('skip libc.so.6 not available');
+}
+?>
+--INI--
+ffi.enable=1
+--FILE--
+<?php
+// Yes, I know that strlen does not return void, but I need a simple & portable test case.
+$libc = FFI::cdef("void strlen(const char *s);", "libc.so.6");
+var_dump($libc->strlen("abc"));
+?>
+DONE
+--EXPECT--
+object(FFI\CData:void)#2 (0) {
+}
+DONE