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Creating a variable sized array at compile time.


I have successfully built arrays at compile-time, basically an array
of pointers to data.  I just use build_constructor() and build the
elements using the CONSTRUCTOR_APPEND_ELT() macro.  Anyways.  I am in
a bit of confusion.  I have a data type, and need the array in this
data type to be variable.  Here is essentially trying to create.  I do
not want to build an array of pointers to data.

struct my_info_t {
    int id;
    int n_members;
    other_data_t members[];
};

I can generate instances of my_info_t fine, with the 'id' and
'n_member' fields all correct; however, the 'members' field never
seems to contain any data.  In fact, the compiler ICEs.  In a loop, I
create a member instance and add it to the 'members' field via:
CONSTRUCTOR_APPEND_ELT(members, NULL, member);

Now, member is created as a global variable and I am appending the
actual decl into the 'members' field.  So, in the line above, 'member'
is actually a decl.

When it comes time to add the 'members' array to to my_info_t
constructor, I create a decl for the members array, so 'members' is a
decl.  The initial part of the
The DECL_INITIAL of 'members' is the result of
build_constructor(member_array_type, members).  I append this decl:
CONSTRUCTOR_APPEND_ELT(myinfo_instance, field, members); // members is a decl

When I finalize the 'members' decl (varpool_finalize_decl) I get a
compiler ICE in cgraphbuild.c:67 (gcc-4.7.1), as the type is
unreachable.  The unreachable being the decl, instance of the member.
Should both the member and members array be DECL nodes that have their
DECL_INITIAL field set to the respected results from calling
build_constructor() for the member instance and members array?

-Matt


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