Re: [PATCH 2/4] allow poisoning input_location in ranges it should not be used

[Jason Merrill <jason@redhat.com>]

On Wed, Jun 30, 2021 at 11:14 AM David Malcolm via Gcc-patches <
gcc-patches@gcc.gnu.org> wrote:

> On Wed, 2021-06-30 at 01:35 -0400, Trevor Saunders wrote:
> > This makes it possible to assert if input_location is used during the
> > lifetime
> > of a scope.  This will allow us to find places that currently use it
> > within a
> > function and its callees, or prevent adding uses within the lifetime
> > of a
> > function after all existing uses are removed.
> >
> > bootstrapped and regtested on x86_64-linux-gnu, ok?
> >
> > Trev
>
> [...snip...]
>
> > diff --git a/gcc/diagnostic.c b/gcc/diagnostic.c
> > index d58586f2526..3f68d1d79eb 100644
> > --- a/gcc/diagnostic.c
> > +++ b/gcc/diagnostic.c
> > @@ -1835,7 +1835,7 @@ internal_error (const char *gmsgid, ...)
> >    auto_diagnostic_group d;
> >    va_list ap;
> >    va_start (ap, gmsgid);
> > -  rich_location richloc (line_table, input_location);
> > +  rich_location richloc (line_table, UNKNOWN_LOCATION);
> >    diagnostic_impl (&richloc, NULL, -1, gmsgid, &ap, DK_ICE);
> >    va_end (ap);
> >
>
> I actually make use of this in the analyzer: the analyzer sets
> input_location to stmt->location when analyzing a given stmt - that
> way, if the analyzer ICEs, the ICE is shown at the code construct that
> crashed the analyzer.
>

C++ template instantiation and constexpr evaluation work similarly.

Jason