Support designated initialization style.

[roptat]

Fixes #32.

• frontc/cabs.ml: Add DESIGNATED expression type for struct
  initialization.
• frontc/cparser.mly: Add rules for compounds (struct initialization). A
  compound contains a list of expressions or designated, but a standard
  initialization cannot be a designated outside a compound.
• frontc/cprint.ml: Print new AST type.
• frontc/ctoxml.ml: Print XML for new designated AST type.
• ctoxml/test.t/c99-struct-initializers.c: New test.
• ctoxml/test.t/run.t: Update expected output for new test.

[roptat]

I don't know if adding a type to the AST is the best thing to do, but I couldn't think of anything else. If you have a better idea, I'd be glad to remove that new type :)

[ivg]

OK, looks good to merge, but can you please first rebase with master (or merge master, doesn't really matter) so that we can sure that the new set of tests is still passing. There is a small conflict in run.t but it is trivial.

[ivg]

Concerning the AST changes, I think we have no other choice (though having it in the expression is a little bit weird, but it looks like that it is indeed where it should be). I have only question about the name DESIGNATED, shouldn't it be a DESIGNATOR, I can't find the authoritative source right away, but it looks like that they are called designators, e.g., from here

Designated initializers, a C99 feature, are supported for aggregate types, including arrays, structures, and unions. A designated initializer, or designator, points out a particular element to be initialized. A designator list is a comma-separated list of one or more designators. A designator list followed by an equal sign constitutes a designation.

Do you have some better reference?

[roptat]

Thanks, will rename and rebase :)

[ivg]

You know, after deeper reading, I think your naming is correct (I still can't find any reference in the C99 standard about designated intializers) but at least this document (it is C++ though) states that the deisgnator is the left-hand side of the designated clause (basically the name part), so DESIGNATED sounds more correct.

Please keep it :)

[roptat]

ah, oops :)

[roptat]

There, rebased and kept DESIGNATED

[ivg]

awesome, thanks!

[ivg]

@roptat, I noticed a new warning,

File "frontc/cparser.mly", line 788, characters 0-21:
Warning: symbol init_comma_expression is unreachable from any of the start symbol(s).

and indeed it is not used anywhere. Is that expected? Then I will delete it if you don't mind.

[roptat]

Ha sorry for the lack of reply, I didn't notice yours. I simply copied the rules, and didn't notice init_comma_expression was only used once, so indeed, you can remove it. Thank you!