On Tue, 19 Sep 2023, Jason Merrill wrote:
> On 9/19/23 12:40, Patrick Palka wrote:
> > Tested on x86_64-pc-linux-gnu, does this look OK for trunk/13?
>
> OK for trunk. What's your argument for backporting?
Thanks. I don't feel strongly about it, but I was thinking that since
we typically backport C++20-only correctness fixes to the most recent
release branch, C++20-only diagnostic improvements might be suitable
too?
>
> > -- >8 --
> >
> > 1. Move class NTTP object pretty printing to a more general spot in
> > the pretty printer.
> > 2. Print the type of an class NTTP object alongside its CONSTRUCTOR
> > value, like dump_expr would have done.
> > 3. Don't pretty print const VIEW_CONVERT_EXPR wrapping class NTTPs.
> >
> > PR c++/111471
> >
> > gcc/cp/ChangeLog:
> >
> > * cxx-pretty-print.cc (cxx_pretty_printer::expression)
> > <case VAR_DECL>: Print the value of a class NTTP object.
> > <case VIEW_CONVERT_EXPR>: Strip cosnt VIEW_CONVERT_EXPR
> > wrappers for class NTTPs.
> > (pp_cxx_template_argument_list): Don't handle the class
> > NTTP objects here.
> >
> > gcc/testsuite/ChangeLog:
> >
> > * g++.dg/concepts/diagnostic19.C: New test.
> > ---
> > gcc/cp/cxx-pretty-print.cc | 19 +++++++++++++++++--
> > gcc/testsuite/g++.dg/concepts/diagnostic19.C | 20 ++++++++++++++++++++
> > 2 files changed, 37 insertions(+), 2 deletions(-)
> > create mode 100644 gcc/testsuite/g++.dg/concepts/diagnostic19.C
> >
> > diff --git a/gcc/cp/cxx-pretty-print.cc b/gcc/cp/cxx-pretty-print.cc
> > index 909a9dc917f..7cd43151592 100644
> > --- a/gcc/cp/cxx-pretty-print.cc
> > +++ b/gcc/cp/cxx-pretty-print.cc
> > @@ -1121,6 +1121,15 @@ cxx_pretty_printer::expression (tree t)
> > t = OVL_FIRST (t);
> > /* FALLTHRU */
> > case VAR_DECL:
> > + if (DECL_NTTP_OBJECT_P (t))
> > + {
> > + /* Print the type followed by the CONSTRUCTOR value of an
> > + NTTP object. */
> > + simple_type_specifier (cv_unqualified (TREE_TYPE (t)));
> > + expression (DECL_INITIAL (t));
> > + break;
> > + }
> > + /* FALLTHRU */
> > case PARM_DECL:
> > case FIELD_DECL:
> > case CONST_DECL:
> > @@ -1261,6 +1270,14 @@ cxx_pretty_printer::expression (tree t)
> > pp_cxx_right_paren (this);
> > break;
> > + case VIEW_CONVERT_EXPR:
> > + if (TREE_CODE (TREE_OPERAND (t, 0)) == TEMPLATE_PARM_INDEX)
> > + {
> > + /* Strip const VIEW_CONVERT_EXPR wrappers for class NTTPs. */
> > + expression (TREE_OPERAND (t, 0));
> > + break;
> > + }
> > + /* FALLTHRU */
> > default:
> > c_pretty_printer::expression (t);
> > break;
> > @@ -1966,8 +1983,6 @@ pp_cxx_template_argument_list (cxx_pretty_printer *pp,
> > tree t)
> > if (TYPE_P (arg) || (TREE_CODE (arg) == TEMPLATE_DECL
> > && TYPE_P (DECL_TEMPLATE_RESULT (arg))))
> > pp->type_id (arg);
> > - else if (VAR_P (arg) && DECL_NTTP_OBJECT_P (arg))
> > - pp->expression (DECL_INITIAL (arg));
> > else
> > pp->expression (arg);
> > }
> > diff --git a/gcc/testsuite/g++.dg/concepts/diagnostic19.C
> > b/gcc/testsuite/g++.dg/concepts/diagnostic19.C
> > new file mode 100644
> > index 00000000000..20cdb63380b
> > --- /dev/null
> > +++ b/gcc/testsuite/g++.dg/concepts/diagnostic19.C
> > @@ -0,0 +1,20 @@
> > +// Verify our pretty printing of class NTTP objects.
> > +// PR c++/111471
> > +// { dg-do compile { target c++20 } }
> > +
> > +struct A { bool value; };
> > +
> > +template<A V>
> > + requires (V.value) // { dg-message {'\(V\).value \[with V =
> > A\{false\}\]'} }
> > +void f();
> > +
> > +template<A V> struct B { static constexpr auto value = V.value; };
> > +
> > +template<class T>
> > + requires T::value // { dg-message {'T::value \[with T = B<A\{false\}>\]'}
> > }
> > +void g();
> > +
> > +int main() {
> > + f<A{false}>(); // { dg-error "no match" }
> > + g<B<A{false}>>(); // { dg-error "no match" }
> > +}
>
>
