Hi, Sergey

thanks for the patch! LGTM

From: Mike Pall <mike>

(cherry picked from commit 899093a9e0fa5b16f27016381ef4b15529dadff2)

According to C++ Standard, the `alignof()` (5.3.6.3) [1] and `sizeof()`
(5.3.3.2) [2] for the reference should be the same as for the referenced
type. This patch fixes the behaviour by following the reference to get a
child id for `alignof()` and `sizeof()` while parsing C definitions via
`ffi.cdef()`.

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

Part of tarantool/tarantool#9924

[1]: https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2016/n4594.pdf#subsection.5.3.6
[2]: https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2016/n4594.pdf#subsection.5.3.3
---
 src/lj_cparse.c                                  |  2 +-
 .../lj-861-ctype-attributes.test.lua             | 16 +++++++++++++++-
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/src/lj_cparse.c b/src/lj_cparse.c
index 01deb3bf..8506d719 100644
--- a/src/lj_cparse.c
+++ b/src/lj_cparse.c
@@ -468,7 +468,7 @@ static void cp_expr_sizeof(CPState *cp, CPValue *k, int wantsz)
   } else {
     cp_expr_unary(cp, k);
   }
-  info = lj_ctype_info(cp->cts, k->id, &sz);
+  info = lj_ctype_info_raw(cp->cts, k->id, &sz);
   if (wantsz) {
     if (sz != CTSIZE_INVALID)
       k->u32 = sz;
diff --git a/test/tarantool-tests/lj-861-ctype-attributes.test.lua b/test/tarantool-tests/lj-861-ctype-attributes.test.lua
index d88045a5..e8b29d67 100644
--- a/test/tarantool-tests/lj-861-ctype-attributes.test.lua
+++ b/test/tarantool-tests/lj-861-ctype-attributes.test.lua
@@ -7,7 +7,7 @@ local tap = require('tap')
 local test = tap.test('lj-861-ctype-attributes')
 local ffi = require('ffi')
 
-test:plan(2)
+test:plan(4)
 
 local EXPECTED_ALIGN = 4
 
@@ -15,6 +15,15 @@ ffi.cdef([[
 struct __attribute__((aligned($))) s_aligned {
   uint8_t a;
 };
+
+struct test_parsing_sizeof {
+  char a[sizeof(struct s_aligned &)];
+};
+
+struct test_parsing_alignof {
+  char a[__alignof__(struct s_aligned &)];
+};
+
 ]], EXPECTED_ALIGN)
 
 local ref_align = ffi.alignof(ffi.typeof('struct s_aligned &'))
@@ -23,4 +32,9 @@ test:is(ref_align, EXPECTED_ALIGN, 'the reference alignment is correct')
 test:is(ref_align, ffi.alignof(ffi.typeof('struct s_aligned')),
         'the alignment of a reference is the same as for the referenced type')
 
+test:is(ffi.sizeof('struct test_parsing_sizeof'), EXPECTED_ALIGN,
+        'correct sizeof during C parsing')
+test:is(ffi.sizeof('struct test_parsing_alignof'), EXPECTED_ALIGN,
+        'correct alignof during C parsing')
+
 test:done(true)