On Wed, 16 Nov 2022 at 11:35, Jonathan Wakely <jwak...@redhat.com> wrote:
>
> On Wed, 16 Nov 2022 at 06:04, François Dumont <frs.dum...@gmail.com> wrote:
> >
> > On 15/11/22 17:17, Jonathan Wakely wrote:
> > > On 06/10/22 19:38 +0200, François Dumont wrote:
> > >> Hi
> > >>
> > >> Looks like the previous patch was not enough. When using it in the
> > >> context of a build without dual abi and versioned namespace I started
> > >> having failures again. I guess I hadn't rebuild everything properly.
> > >>
> > >> This time I think the problem was in those lines:
> > >>
> > >> if self.type_obj == type_obj:
> > >> return strip_inline_namespaces(self.name)
> > >>
> > >> I've added a call to gdb.types.get_basic_type so that we do not compare
> > >> a type with its typedef.
> > >>
> > >> Thanks for the pointer to the doc !
> > >>
> > >> Doing so I eventually use your code Jonathan to make FilteringTypeFilter
> > >> more specific to a given instantiation.
> > >>
> > >> libstdc++: Fix gdb FilteringTypePrinter
> > >>
> > >> Once we found a matching FilteringTypePrinter instance we look for
> > >> the associated
> > >> typedef and check that the returned Python Type is equal to the
> > >> Type to recognize.
> > >> But gdb Python Type includes properties to distinguish a typedef
> > >> from the actual
> > >> type. So use gdb.types.get_basic_type to check if we are indeed on
> > >> the same type.
> > >>
> > >> Additionnaly enhance FilteringTypePrinter matching mecanism by
> > >> introducing targ1 that,
> > >> if not None, will be used as the 1st template parameter.
> > >>
> > >> libstdc++-v3/ChangeLog:
> > >>
> > >> * python/libstdcxx/v6/printers.py (FilteringTypePrinter):
> > >> Rename 'match' field
> > >> 'template'. Add self.targ1 to specify the first template
> > >> parameter of the instantiation
> > >> to match.
> > >> (add_one_type_printer): Add targ1 optional parameter,
> > >> default to None.
> > >> Use gdb.types.get_basic_type to compare the type to
> > >> recognize and the type
> > >> returned from the typedef lookup.
> > >> (register_type_printers): Adapt calls to
> > >> add_one_type_printers.
> > >>
> > >> Tested under Linux x86_64 normal, version namespace with or without dual
> > >> abi.
> > >>
> > >> François
> > >>
> > >> diff --git a/libstdc++-v3/python/libstdcxx/v6/printers.py
> > >> b/libstdc++-v3/python/libstdcxx/v6/printers.py
> > >> index 0fa7805183e..52339b247d8 100644
> > >> --- a/libstdc++-v3/python/libstdcxx/v6/printers.py
> > >> +++ b/libstdc++-v3/python/libstdcxx/v6/printers.py
> > >> @@ -2040,62 +2040,72 @@ def add_one_template_type_printer(obj, name,
> > >> defargs):
> > >>
> > >> class FilteringTypePrinter(object):
> > >> r"""
> > >> - A type printer that uses typedef names for common template
> > >> specializations.
> > >> + A type printer that uses typedef names for common template
> > >> instantiations.
> > >>
> > >> Args:
> > >> - match (str): The class template to recognize.
> > >> + template (str): The class template to recognize.
> > >> name (str): The typedef-name that will be used instead.
> > >> + targ1 (str): The first template argument.
> > >> + If arg1 is provided (not None), only template
> > >> instantiations with this type
> > >> + as the first template argument, e.g. if
> > >> template='basic_string<targ1'
> > >>
> > >> - Checks if a specialization of the class template 'match' is the
> > >> same type
> > >> + Checks if an instantiation of the class template 'template' is
> > >> the same type
> > >> as the typedef 'name', and prints it as 'name' instead.
> > >>
> > >> - e.g. if an instantiation of std::basic_istream<C, T> is the same
> > >> type as
> > >> + e.g. for template='basic_istream', name='istream', if any
> > >> instantiation of
> > >> + std::basic_istream<C, T> is the same type as std::istream then
> > >> print it as
> > >> + std::istream.
> > >> +
> > >> + e.g. for template='basic_istream', name='istream', targ1='char',
> > >> if any
> > >> + instantiation of std::basic_istream<char, T> is the same type as
> > >> std::istream then print it as std::istream.
> > >> """
> > >
> > > These are template specializations, not instantiations. Please undo
> > > the changes to the comments, because the comments are 100% correct
> > > now, and would become wrong with this patch.
> > >
> > > template<class T, class U> struct foo { };
> > > using F = foo<int, int>; // #1
> > > template<class T> struct foo<T, void> { }; // #2
> > > template<> struct foo<void, void> { }; // #3
> > >
> > > #1 is a *specialization* of the class template foo. It is
> > > *instantiated* when you construct one or depend on its size, or its
> > > members.
> > > #2 is a *partial specialization* and #3 is an explicit specialization.
> > > But #1 is a speclialization, not an instantiation.
> > >
> > > Instantiation is a process that happens during compilation. A
> > > specialization is a type (or function, or variable) generated from a
> > > template by substituting arguments for the template parameters. The
> > > python type printer matches specializations.
> >
> > Lesson learned, thanks.
> >
> > Maybe comment on line 169 is wrong then. I think there is a clue in the
> > function name 'is_specialization_of' :-)
>
> Good point! Thanks, I'll fix it.
>
> >
> > >
> > >>
> > >> - def __init__(self, match, name):
> > >> - self.match = match
> > >> + def __init__(self, template, name, targ1):
> > >
> > > Is there a reason to require targ1 here, instead of making it
> > > optional, by using =None as the default?
> >
> > In your original, and I know untested, proposal it was not working.
> >
> > The function add_one_type_printer was missing to pass its targ1
> > parameter to the FilteringTypePrinter ctor but thanks to the default
> > value it was un-noticed by the interpreter.
>
> My untested patch had this, which adds it, doesn't it?
>
> -def add_one_type_printer(obj, match, name):
> - printer = FilteringTypePrinter('std::' + match, 'std::' + name)
> +def add_one_type_printer(obj, match, name, targ1 = None):
> + printer = FilteringTypePrinter('std::' + match, 'std::' + name, targ1)
> gdb.types.register_type_printer(obj, printer)
> if _versioned_namespace:
> ns = 'std::' + _versioned_namespace
> - printer = FilteringTypePrinter(ns + match, ns + name)
> + printer = FilteringTypePrinter(ns + match, ns + name, targ1)
> gdb.types.register_type_printer(obj, printer)
>
>
> I think FilteringTypePrinter should be usable without specifying None
> explicitly as the argument. Even if we don't actually use it that way
> today, it seems like a better API. If the argument is optional, then
> the idiomatic way to express that is to give it a default, not require
> None to be passed.
>
> I'll add that default argument, but first I need to figure out why I'm
> seeing new failures for libfundts.cc with -D_GLIBCXX_USE_CXX11_ABI=0.
> Your patch has introduced this new error:
>
> $12 = Python Exception <class 'gdb.error'>: No type named
> std::experimental::fundamentals_v1::any::_Manager_internal<std::__cxx11::basic_string<char,
> std::char_traits<char>, std::allocator<char> >>.
> got: $12 = Python Exception <class 'gdb.error'>: No type named
> std::experimental::fundamentals_v1::any::_Manager_internal<std::__cxx11::basic_string<char,
> std::char_traits<char>, std::allocator<char> >>.
> FAIL: libstdc++-prettyprinters/libfundts.cc print as
The problem happens here in StdExpAnyPrinter:
mgrname = m.group(1)
# FIXME need to expand 'std::string' so that gdb.lookup_type works
if 'std::string' in mgrname:
mgrname = re.sub("std::string(?!\w)",
str(gdb.lookup_type('std::string').strip_typedefs()), m.group(1))
mgrtype = gdb.lookup_type(mgrname)
After your patch, gdb.lookup_type('std::string').strip_typedefs() is
returning std::__cxx11::basic_string<char,...> which is not the
correct type for this specialization of the any manager function. It
contains a std::basic_string<char,...>.
