On Tue, Dec 01, 2020 at 04:05:22PM -0500, Jason Merrill wrote:
> > I see cp_parser_late_parsing_default_args calls push_defarg_context,
> > so perhaps it could check default_arg_context vector, except that
> > convert_default_arg calls that too around calling break_out_target_exprs
> > which in the patch is used to perform the late evaluation of the
> > std::source_location::current() calls. So it might need to temporarily
> > pop_defarg_context before break_out_target_exprs and push it again?
>
> How about forcing the constant evaluation in bot_manip?
That is probably a good idea anyway.
> Or simpler might be to always defer immediate evaluation of
> source_location::current() until genericize time.
Will try this too.
Though, I still wonder if it will be ok that we'll evaluate immediate
functions other than std::source_location::current() during the late
parsing of default arguments.
Testcase could be something like:
consteval bool foo (bool x) { if (x) throw 1; return false; }
consteval bool bar (bool x = foo (true)) { return true; }
struct S
{
consteval static bool baz (bool x = foo (true)) { return true; }
};
constexpr bool a = bar (true);
constexpr bool b = S::baz (true);
We accept now bar, but reject baz.
I think the foo (true) expressions are in both cases in
immediate function context and therefore foo (true) calls are there
not immediate invocations (sure, if one calls bar () or S::baz ()
then it will be invalid anyway).
Jakub
