Ping. As with the patch for DW_TAG_atomic_type this is only experimental
at this time, but feedback appreciated.
There is a corresponding patch for GDB:
https://sourceware.org/ml/gdb-patches/2014-07/msg00199.html
gcc/ChangeLog
* dwarf2out.c (decl_user_align): New function.
I'm dubious about adding a tag for alignment, because it doesn't
participate in the type system; in C and C++, it's an attribute of a
struct or variable declaration, but the variable has the same type as
another variable without the explicit alignment. In the GNU extension
it can also be
gcc/ChangeLog
* dwarf2out.c (decl_user_align): New function.
(type_user_align): Likewise.
(modified_type_die): Add and handle align argument.
(add_bound_info): Likewise.
(base_type_for_mode): Call modified_type_die with zero user align.
