Hi, Sergey

thanks for the patch! LGTM with a nit below.

From: Mike Pall <mike>

Reported by Eric Gouyer.

(cherry picked from commit 27a6fee82e91319bbed8c3aa443aa2b0f1b0a470)

Before the patch, `ffi.metatype()` raises an error when calling it on
ctype with attributes.  This patch fixes the behaviour by using

`ctype_raw()` instead of `ctype_get()` to follow child ctypes unless
there are no attributes on the ctype.

Sergey Kaplun:
* added the description and the test for the problem

Part of tarantool/tarantool#9924
---
 src/lib_ffi.c                                         |  2 +-
 test/tarantool-tests/lj-861-ctype-attributes.test.lua | 10 +++++++---
 2 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/src/lib_ffi.c b/src/lib_ffi.c
index 2bfca25a..dfb01658 100644
--- a/src/lib_ffi.c
+++ b/src/lib_ffi.c
@@ -770,7 +770,7 @@ LJLIB_CF(ffi_metatype)
   CTypeID id = ffi_checkctype(L, cts, NULL);
   GCtab *mt = lj_lib_checktab(L, 2);
   GCtab *t = cts->miscmap;
-  CType *ct = ctype_get(cts, id);  /* Only allow raw types. */
+  CType *ct = ctype_raw(cts, id);
   TValue *tv;
   GCcdata *cd;
   if (!(ctype_isstruct(ct->info) || ctype_iscomplex(ct->info) ||
diff --git a/test/tarantool-tests/lj-861-ctype-attributes.test.lua b/test/tarantool-tests/lj-861-ctype-attributes.test.lua
index e8b29d67..a407fae0 100644
--- a/test/tarantool-tests/lj-861-ctype-attributes.test.lua
+++ b/test/tarantool-tests/lj-861-ctype-attributes.test.lua
@@ -7,14 +7,14 @@ local tap = require('tap')
 local test = tap.test('lj-861-ctype-attributes')
 local ffi = require('ffi')
 
-test:plan(4)
+test:plan(5)
 
 local EXPECTED_ALIGN = 4
 
 ffi.cdef([[
-struct __attribute__((aligned($))) s_aligned {
+typedef struct __attribute__((aligned($))) s_aligned {
   uint8_t a;
-};
+} s_aligned;
 
 struct test_parsing_sizeof {
   char a[sizeof(struct s_aligned &)];
@@ -37,4 +37,8 @@ test:is(ffi.sizeof('struct test_parsing_sizeof'), EXPECTED_ALIGN,
 test:is(ffi.sizeof('struct test_parsing_alignof'), EXPECTED_ALIGN,
         'correct alignof during C parsing')
 
+local ok, _ = pcall(ffi.metatype, 's_aligned', {})
+
+test:ok(ok, 'ffi.metatype is called at the structure with attributes')
+
 test:done(true)