Re: [PATCH 1/1] gdb: Enable complete to show members of anonymous classes/structs.

[Tom Tromey <tom@tromey.com>]

>>>>> "Felix" == Felix Willgerodt via Gdb-patches <gdb-patches@sourceware.org> writes:

Hello.  Thank you for the patch.  I'm sorry it took so long to review,
but I appreciate your persistence in pinging it.

Felix> After:
Felix> ~~~
Felix> (gdb) p unique_name_foo
Felix> $1 = 5
Felix> (gdb) complete p unique_name_fo
Felix> p unique_name_foo
Felix> (gdb)
Felix> ~~~

The outcome seems like what we want.

Felix> As we are able to print the member we should be able to complete on it.
Felix> GDB doesn't look at "this" and its members for complete, while it does
Felix> when printing.  So I tried fixing that.
Felix> I saw that "this" is always represented as a PTR type with the symbol
Felix> class LOC_COMPUTED (with g++ 11.3.1, clang++ 10.0.1 and icpx 2022.1).

Felix> Not knowing too much about LOC_COMPUTED, I am assuming that this is the right
Felix> symbol class for this case and that we should adjust
Felix> completion_list_add_fields() for it.
Felix> But it could very well be that I missed something.  Any comments welcome!

I don't think there's any requirement that 'this' be LOC_COMPUTED.

LOC_COMPUTED just means that the symbol's address is computed via some
function call (normally into the DWARF code to handle an exprloc).
However, nothing says it couldn't be LOC_REGISTER or LOC_ARG or
something.

Felix> +  if (sym->aclass () == LOC_TYPEDEF
Felix> +      || (sym->aclass () == LOC_COMPUTED && t->code () == TYPE_CODE_PTR))

It seems like this could match many local symbols -- like, nearly any
local variable that has pointer type.  But, completing on these fields
is not desirable; instead you only want to examine 'this'.

Instead you probably want something like what lookup_symbol_aux does:

  if (is_a_field_of_this != NULL && domain != STRUCT_DOMAIN)
    {
      result = lookup_language_this (langdef, block);

      if (result.symbol)

That is, use the current language (or in this case perhaps some search
language, I don't really know) to find the name of 'this', then use it
if this symbol matches.  Probably this should be done in the caller to
avoid a lot of repeated calls.

Felix> +	for (int j = TYPE_N_BASECLASSES (t); j < t->num_fields (); j++)
Felix>  	  if (t->field (j).name ())
Felix>  	    completion_list_add_name (tracker, sym->language (),

To me this loop looks incomplete, because it seems like it ought to walk
over superclasses as well.  Not your bug but if you really want this to
work correctly, it's worth fixing (and adding a test for).

Tom