I tested it on linux (64-bit distro), and it segfaults as well:
-----
$ echo "struct S { ushort a, b; ubyte c, d; } struct T { ushort
e; S s; }" > test.d
$ dmd -v test.d
binary dmd
version v2.069.0
config /etc/dmd.conf
parse test
importall test
import object (/usr/include/dmd/druntime/import/object.d)
semantic test
Segmentation fault
$ uname -r
3.13.0-37-generic
$ cat /etc/issue
Linux Mint 17.1 Rebecca \n \l
$ dmd --version
DMD64 D Compiler v2.069.0
Copyright (c) 1999-2015 by Digital Mars written by Walter Bright
-----
It doesn't crash if compiled in 32-bit:
-----
$ dmd -v -m32 test.d
binary dmd
version v2.069.0
config /etc/dmd.conf
parse test
importall test
import object (/usr/include/dmd/druntime/import/object.d)
semantic test
semantic2 test
semantic3 test
code test
gcc test.o -o test -m32 -L/usr/lib/i386-linux-gnu -Xlinker
--export-dynamic -Xlinker -Bstatic -lphobos2 -Xlinker -Bdynamic
-lpthread -lm -lrt -ldl
/usr/lib/gcc/x86_64-linux-gnu/4.8/../../../../lib32/crt1.o: In
function `_start':
(.text+0x18): undefined reference to `main'
collect2: error: ld returned 1 exit status
--- errorlevel 1
-----
Using ubyte[2] or swapping the fields also solve the issue as
mentioned above.
I also reproduce the issue using DMD v2.069.2.
So it may be good to add that information in the bug-report.
