Re: RFC: handle case arising from GCC PR 47510

Jan Kratochvil
2011-02-02T21:12:33Z

Hi Tom,

> --- a/gdb/dwarf2read.c
> +++ b/gdb/dwarf2read.c
[...]
> + if (cu->language == language_cplus
> + && TYPE_CODE (TYPE_TARGET_TYPE (this_type)) == TYPE_CODE_STRUCT
> + && TYPE_TAG_NAME (TYPE_TARGET_TYPE (this_type)) == NULL
> + && maybe_smash_one_typedef (this_type, dwarf2_name (die, cu)))
> + {
> + /* We turned this typedef into a real structure type, so
> + make a pretend DIE to get new_symbol to do the right
> + thing. */
> + struct die_info fake = *die;

fake.attrs are invalid now while being accessed by new_symbol.

> +
> + fake.tag = DW_TAG_structure_type;
> + new_symbol (&fake, TYPE_TARGET_TYPE (this_type), cu);
> + }

> --- /dev/null
> +++ b/gdb/testsuite/gdb.cp/anon-struct.cc
> @@ -0,0 +1,15 @@
> +class C {

No copyright needed?

> +public:
> + C() {}
> + ~C() {}

If the destructor is not present maybe_smash_one_typedef() will not work. And
GDB crashes now due to it, that should be sanity-protected anyway.

> +};
> +
> +typedef struct {
> + C m;
> +} t;
> +typedef t S;
> +S v;

I would remove the intermediate type `S', it was there fore more illustrative
purposes.

> --- /dev/null
> +++ b/gdb/testsuite/gdb.cp/anon-struct.exp
> @@ -0,0 +1,25 @@
> +# Tests for anonymous union support.
> +# Copyright 2011 Free Software Foundation, Inc.
> +
> +# This program is free software; you can redistribute it and/or modify
> +# it under the terms of the GNU General Public License as published by
> +# the Free Software Foundation; either version 3 of the License, or
> +# (at your option) any later version.
> +#
> +# This program is distributed in the hope that it will be useful,
> +# but WITHOUT ANY WARRANTY; without even the implied warranty of
> +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> +# GNU General Public License for more details.
> +#
> +# You should have received a copy of the GNU General Public License
> +# along with this program. If not, see <http://www.gnu.org/licenses/>.
> +
> +set testfile anon-struct
> +set srcfile ${testfile}.cc
> +set binfile ${objdir}/${subdir}/${testfile}
> +if { [prepare_for_testing ${testfile}.exp ${testfile} ${srcfile} {debug c++}] } {
> + return -1
> +}
> +
> +gdb_test "ptype t::t" "type = void \\(t \\* const\\)" \
> + "print type of t::t"
> diff --git a/gdb/valops.c b/gdb/valops.c
> index 24c2269..0287092 100644
> --- a/gdb/valops.c
> +++ b/gdb/valops.c
> @@ -3238,25 +3238,32 @@ value_struct_elt_for_reference (struct type *domain, int offset,
> j = -1;
> - for (ii = 0; ii < TYPE_FN_FIELDLIST_LENGTH (t, i);
> - ++ii)
> + for (ii = 0; ii < len; ++ii)
> {
> /* Skip artificial methods. This is necessary if,
> for example, the user wants to "print
> subclass::subclass" with only one user-defined
> - constructor. There is no ambiguity in this
> - case. */
> + constructor. There is no ambiguity in this case.
> + We are careful here to allow artificial methods
> + if they are the unique result. */
> if (TYPE_FN_FIELD_ARTIFICIAL (f, ii))
> - continue;
> + {
> + if (j == -1)
> + j = ii;
> + continue;
> + }
>
> /* Desired method is ambiguous if more than one
> method is defined. */
> - if (j != -1)
> + if (j != -1 && !TYPE_FN_FIELD_ARTIFICIAL (f, j))
> error (_("non-unique member `%s' requires "
> "type instantiation"), name);
>
> j = ii;
> }
> +
> + if (j == -1)
> + error (_("no matching member function"));
> }

I do not fully grok this change, it goes half way. Why two artificial methods
are not non-unique?

Thanks,
Jan