On Fri, 16 Feb 2024, Marek Polacek wrote:
> On Fri, Feb 16, 2024 at 03:58:02PM -0500, Jason Merrill wrote:
> > On 2/15/24 17:17, Marek Polacek wrote:
> > > Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
> > >
> > > By the ??? below I mean that maybe_instantiate_noexcept could return
> > > a tristate, and then maybe_check_overriding_exception_spec could check
> > >
> > > if (maybe_instantiate_noexcept ().is_unknown ())
> > > return true;
> > >
> > > and we don't have to add any new checks to maybe_check_o_e_spec.
> > >
> > > -- >8 --
> > > Here we find ourselves in maybe_check_overriding_exception_spec in
> > > a template context where we can't instantiate a dependent noexcept.
> > > That's OK, but we have to defer the checking otherwise we give wrong
> > > errors.
> > >
> > > PR c++/113158
> > >
> > > gcc/cp/ChangeLog:
> > >
> > > * search.cc (maybe_check_overriding_exception_spec): Defer checking
> > > when a noexcept couldn't be instantiated.
> > >
> > > gcc/testsuite/ChangeLog:
> > >
> > > * g++.dg/cpp0x/noexcept83.C: New test.
> > > ---
> > > gcc/cp/search.cc | 7 +++++
> > > gcc/testsuite/g++.dg/cpp0x/noexcept83.C | 37 +++++++++++++++++++++++++
> > > 2 files changed, 44 insertions(+)
> > > create mode 100644 gcc/testsuite/g++.dg/cpp0x/noexcept83.C
> > >
> > > diff --git a/gcc/cp/search.cc b/gcc/cp/search.cc
> > > index c948839dc53..73d254d6b84 100644
> > > --- a/gcc/cp/search.cc
> > > +++ b/gcc/cp/search.cc
> > > @@ -1975,6 +1975,13 @@ maybe_check_overriding_exception_spec (tree
> > > overrider, tree basefn)
> > > || UNPARSED_NOEXCEPT_SPEC_P (over_throw))
> > > return true;
> > > + /* We also have to defer checking when we're in a template and couldn't
> > > + instantiate the noexcept yet.
> > > + ??? maybe_instantiate_noexcept already checked these. Use
> > > tristate? */
> > > + if (type_dependent_expression_p (base_throw)
> > > + || type_dependent_expression_p (over_throw))
> >
> > I think we also want to avoid comparing value-dependent expressions, but
> > actually checking either one seems like more work than needed here; I'd
> > think we want to defer in a template if the specifiers aren't both exactly
> > true or false.
>
> Yeah, that'll work too. So like this?
>
> Bootstrap/regtest running; dg.exp passed. FWIW, the new check only
> triggered on the new test.
>
> Thanks,
>
> -- >8 --
> Here we find ourselves in maybe_check_overriding_exception_spec in
> a template context where we can't instantiate a dependent noexcept.
> That's OK, but we have to defer the checking otherwise we give wrong
> errors.
>
> PR c++/113158
>
> gcc/cp/ChangeLog:
>
> * search.cc (maybe_check_overriding_exception_spec): Defer checking
> when a noexcept couldn't be instantiated & evaluated to false/true.
>
> gcc/testsuite/ChangeLog:
>
> * g++.dg/cpp0x/noexcept83.C: New test.
> ---
> gcc/cp/search.cc | 11 ++++++++
> gcc/testsuite/g++.dg/cpp0x/noexcept83.C | 37 +++++++++++++++++++++++++
> 2 files changed, 48 insertions(+)
> create mode 100644 gcc/testsuite/g++.dg/cpp0x/noexcept83.C
>
> diff --git a/gcc/cp/search.cc b/gcc/cp/search.cc
> index c948839dc53..554ba71f4a7 100644
> --- a/gcc/cp/search.cc
> +++ b/gcc/cp/search.cc
> @@ -1975,6 +1975,17 @@ maybe_check_overriding_exception_spec (tree overrider,
> tree basefn)
> || UNPARSED_NOEXCEPT_SPEC_P (over_throw))
> return true;
>
> + /* We also have to defer checking when we're in a template and couldn't
> + instantiate & evaluate the noexcept to true/false. */
> + if (processing_template_decl)
> + if ((base_throw
> + && (base_throw != noexcept_true_spec
> + || base_throw != noexcept_false_spec))
Shouldn't these innermost || be &&?
> + || (over_throw
> + && (over_throw != noexcept_true_spec
> + || over_throw != noexcept_false_spec)))
> + return true;
> +
> if (!comp_except_specs (base_throw, over_throw, ce_derived))
> {
> auto_diagnostic_group d;
> diff --git a/gcc/testsuite/g++.dg/cpp0x/noexcept83.C
> b/gcc/testsuite/g++.dg/cpp0x/noexcept83.C
> new file mode 100644
> index 00000000000..47832bbb44d
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/cpp0x/noexcept83.C
> @@ -0,0 +1,37 @@
> +// PR c++/113158
> +// { dg-do compile { target c++11 } }
> +
> +template<typename T>
> +struct V {
> + static constexpr bool t = false;
> +};
> +struct base {
> + virtual int f() = 0;
> +};
> +
> +template<typename T>
> +struct derived : base {
> + int f() noexcept(V<T>::t) override;
> +};
> +
> +struct base2 {
> + virtual int f() noexcept = 0;
> +};
> +
> +template<bool B>
> +struct W {
> + static constexpr bool t = B;
> +};
> +
> +template<bool B>
> +struct derived2 : base2 {
> + int f() noexcept(W<B>::t) override; // { dg-error "looser exception
> specification" }
> +};
> +
> +void
> +g ()
> +{
> + derived<int> d1;
> + derived2<false> d2; // { dg-message "required from here" }
> + derived2<true> d3;
> +}
>
> base-commit: 40b8d7b73ad2ce498758c1d9bd38ebdbc26b918b
> --
> 2.43.2
>
>
