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Re: [RFC] 12266 Fallout
- From: Jan Kratochvil <jan dot kratochvil at redhat dot com>
- To: Keith Seitz <keiths at redhat dot com>
- Cc: gdb-patches at sourceware dot org
- Date: Fri, 26 Aug 2011 20:31:08 +0200
- Subject: Re: [RFC] 12266 Fallout
- References: <4E56D4A3.7000306@redhat.com>
On Fri, 26 Aug 2011 01:02:59 +0200, Keith Seitz wrote:
> The reporter's test case (C++):
>
> typedef std::string foo;
> void calltest (foo) {}
>
> Setting a break at "calltest(foo)" does not work because
> inspect_type (part of 12266 patchset) uses check_typedef, which
> resolves foo -> std::string -> std::basic_string<char,
> std::char_traits<char>, std::alloactor<char> >. But because we are
> no longer using DMGL_VERBOSE in dwarf2_physname (and other places)
> to do demangling, the symbol table actually stores
> "calltest(std::string)".
check_typedef always unwinds only the toplevel typedefs, not any inner ones.
I think you should move the comparison block
/* Ignore any typedefs that should not be substituted. */
for (i = 0; i < ARRAY_SIZE (ignore_typedefs); ++i)
{
if (strcmp (name, ignore_typedefs[i]) == 0)
return 0;
}
into the later comparisons:
/* Find the last typedef for the type. */
while (TYPE_TARGET_TYPE (last) != NULL
&& (TYPE_CODE (TYPE_TARGET_TYPE (last))
== TYPE_CODE_TYPEDEF))
last = TYPE_TARGET_TYPE (last);
and it would get properly caught, wouldn't be?
> There are two ways I can see to fix this.
> 1) Add DMGL_VERBOSE where it is needed so that NO typedefs ever
> appear in a (non-TYPE_CODE_TYPEDEF) symbol's name, i.e, store
> "calltest(std::basic_string<...>)" in the symbol table instead of
> "calltest(std::string)".
> Actually in this case, the "right" output would be "calltest(foo)",
> but that is a different, but related, problem, for which I developed
> a patch a long time ago, part of the first 12266 patch submissions
> (dwarf2_print_name).
As I stated off-list before I agree the primary goal is to make working
`break func(any_form_of_types)'.
And as also Tom said when there is the possibility to print the DWARF type
- incl. typedefs - it should be also printed as was implemented in:
But if you just lookup the minimal (ELF) symbol - where the dwarf2_print_name
form cannot apply - by:
(gdb) info sym 0x0000003f1b25ed70
I guess it should say:
std::hash<std::string>::operator()(std::string) const in section .text of /usr/lib64/libstdc++.so.6
and not:
std::hash<std::basic_string<char, std::char_traits<char>, std::allocator<char> > >::operator()(std::basic_string<char, std::char_traits<char>, std::allocator<char> >) const
in section .text of /usr/lib64/libstdc++.so.6
while nm -C says:
0000003f1b25ed70 T std::hash<std::string>::operator()(std::string) const
IMO if GDB starts to use DMGL_VERBOSE we should ask binutils to use
DMGL_VERBOSE for `nm -C' and other tools there.
> So, I humbly ask maintainers:
>
> - Shall I continue #1 and start submitting patches?
> - Shall I start teaching gdb about std::string et al and how to deal
> with them in the environment we have today?
> - Have I missed something that would be preferable to anything I've
> mentioned?
I would prefer to keep `std::string' to be `std::string' as possible, which
I naively believe could be done without modifying/duplicating check_typedef by
the change suggested above.
Thanks,
Jan