Hi, Sergey thanks for the patch! LGTM On 03.06.2024 17:33, Sergey Kaplun wrote: > From: Mike Pall > > Reported by Eric Gouyer. > > (cherry picked from commit 36b2962d400db3981a7d7322f85c469240eb6f3b) > > According to C++ Standard (5.3.6.3) [1], the `alignof()` 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 > `ffi.alignof()`. > > 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 > --- > src/lib_ffi.c | 2 +- > src/lj_ctype.c | 8 ++++++ > src/lj_ctype.h | 1 + > .../lj-861-ctype-attributes.test.lua | 26 +++++++++++++++++++ > 4 files changed, 36 insertions(+), 1 deletion(-) > create mode 100644 test/tarantool-tests/lj-861-ctype-attributes.test.lua > > diff --git a/src/lib_ffi.c b/src/lib_ffi.c > index e60e7b19..2bfca25a 100644 > --- a/src/lib_ffi.c > +++ b/src/lib_ffi.c > @@ -639,7 +639,7 @@ LJLIB_CF(ffi_alignof) LJLIB_REC(ffi_xof FF_ffi_alignof) > CTState *cts = ctype_cts(L); > CTypeID id = ffi_checkctype(L, cts, NULL); > CTSize sz = 0; > - CTInfo info = lj_ctype_info(cts, id, &sz); > + CTInfo info = lj_ctype_info_raw(cts, id, &sz); > setintV(L->top-1, 1 << ctype_align(info)); > return 1; > } > diff --git a/src/lj_ctype.c b/src/lj_ctype.c > index 0874fa61..83042118 100644 > --- a/src/lj_ctype.c > +++ b/src/lj_ctype.c > @@ -345,6 +345,14 @@ CTInfo lj_ctype_info(CTState *cts, CTypeID id, CTSize *szp) > return qual; > } > > +/* Ditto, but follow a reference. */ > +CTInfo lj_ctype_info_raw(CTState *cts, CTypeID id, CTSize *szp) > +{ > + CType *ct = ctype_get(cts, id); > + if (ctype_isref(ct->info)) id = ctype_cid(ct->info); > + return lj_ctype_info(cts, id, szp); > +} > + > /* Get ctype metamethod. */ > cTValue *lj_ctype_meta(CTState *cts, CTypeID id, MMS mm) > { > diff --git a/src/lj_ctype.h b/src/lj_ctype.h > index fce29409..8edbd561 100644 > --- a/src/lj_ctype.h > +++ b/src/lj_ctype.h > @@ -467,6 +467,7 @@ LJ_FUNC CType *lj_ctype_rawref(CTState *cts, CTypeID id); > LJ_FUNC CTSize lj_ctype_size(CTState *cts, CTypeID id); > LJ_FUNC CTSize lj_ctype_vlsize(CTState *cts, CType *ct, CTSize nelem); > LJ_FUNC CTInfo lj_ctype_info(CTState *cts, CTypeID id, CTSize *szp); > +LJ_FUNC CTInfo lj_ctype_info_raw(CTState *cts, CTypeID id, CTSize *szp); > LJ_FUNC cTValue *lj_ctype_meta(CTState *cts, CTypeID id, MMS mm); > LJ_FUNC GCstr *lj_ctype_repr(lua_State *L, CTypeID id, GCstr *name); > LJ_FUNC GCstr *lj_ctype_repr_int64(lua_State *L, uint64_t n, int isunsigned); > diff --git a/test/tarantool-tests/lj-861-ctype-attributes.test.lua b/test/tarantool-tests/lj-861-ctype-attributes.test.lua > new file mode 100644 > index 00000000..d88045a5 > --- /dev/null > +++ b/test/tarantool-tests/lj-861-ctype-attributes.test.lua > @@ -0,0 +1,26 @@ > +local tap = require('tap') > + > +-- Test file to demonstrate LuaJIT incorrect behaviour during > +-- parsing and working with ctypes with attributes. > +-- See also:https://github.com/LuaJIT/LuaJIT/issues/861. > + > +local test = tap.test('lj-861-ctype-attributes') > +local ffi = require('ffi') > + > +test:plan(2) > + > +local EXPECTED_ALIGN = 4 > + > +ffi.cdef([[ > +struct __attribute__((aligned($))) s_aligned { > + uint8_t a; > +}; > +]], EXPECTED_ALIGN) > + > +local ref_align = ffi.alignof(ffi.typeof('struct s_aligned &')) > + > +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:done(true)