| Message ID | 20230130213639.2585560-1-ppalka@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | c++: ICE on unviable/ambiguous constrained dtors [PR96745] | expand |
On 1/30/23 16:36, Patrick Palka wrote: > Here we're crashing from check_bases_and_members due to > CLASSTYPE_DESTRUCTOR being an OVERLOAD which, due to the pruning > performed by add_method, should only happen if there is no viable > destructor or the destructor is ambiguous. > > This patch fixes this by making check_bases_and_members naturally handle > CLASSTYPE_DESTRUCTOR being an OVERLOAD. It's then convenient to prune > the OVERLOAD after diagnosing the inevitable OR failure in check_methods. > > Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK for > trunk and perhaps 12? OK for trunk, this doesn't seem important to backport. > PR c++/96745 > > gcc/cp/ChangeLog: > > * class.cc (check_methods): Diagnose an unviable OVERLOAD > set for CLASSTYPE_DESTRUCTOR differently from an ambiguous one. > Then prune the OVERLOAD to a single function. > (check_bases_and_members): Handle CLASSTYPE_DESTRUCTOR being > an OVERLOAD when calling deduce_noexcept_on_destructor. > Document why it has to be called before check_methods. > > gcc/testsuite/ChangeLog: > > * g++.dg/cpp2a/concepts-dtor1.C: New test. > --- > gcc/cp/class.cc | 22 ++++++++++++++++++--- > gcc/testsuite/g++.dg/cpp2a/concepts-dtor1.C | 18 +++++++++++++++++ > 2 files changed, 37 insertions(+), 3 deletions(-) > create mode 100644 gcc/testsuite/g++.dg/cpp2a/concepts-dtor1.C > > diff --git a/gcc/cp/class.cc b/gcc/cp/class.cc > index d3ce8532d56..c6878cba2ae 100644 > --- a/gcc/cp/class.cc > +++ b/gcc/cp/class.cc > @@ -4808,9 +4808,23 @@ check_methods (tree t) > in that class with an empty argument list to select the destructor > for the class, also known as the selected destructor. The program > is ill-formed if overload resolution fails. */ > + int viable = 0; > + for (tree fn : ovl_range (dtor)) > + if (constraints_satisfied_p (fn)) > + ++viable; > + gcc_checking_assert (viable != 1); > + > auto_diagnostic_group d; > - error_at (location_of (t), "destructor for %qT is ambiguous", t); > + if (viable == 0) > + error_at (location_of (t), "no viable destructor for %qT", t); > + else > + error_at (location_of (t), "destructor for %qT is ambiguous", t); > print_candidates (dtor); > + > + /* Arbitrarily prune the overload set to a single function for > + sake of error recovery. */ > + tree *slot = find_member_slot (t, dtor_identifier); > + *slot = get_first_fn (dtor); > } > else if (user_provided_p (dtor)) > TYPE_HAS_NONTRIVIAL_DESTRUCTOR (t) = true; > @@ -6048,10 +6062,12 @@ check_bases_and_members (tree t) > check_bases (t, &cant_have_const_ctor, &no_const_asn_ref); > > /* Deduce noexcept on destructor. This needs to happen after we've set > - triviality flags appropriately for our bases. */ > + triviality flags appropriately for our bases, and before checking > + overriden virtual functions via check_methods. */ > if (cxx_dialect >= cxx11) > if (tree dtor = CLASSTYPE_DESTRUCTOR (t)) > - deduce_noexcept_on_destructor (dtor); > + for (tree fn : ovl_range (dtor)) > + deduce_noexcept_on_destructor (fn); > > /* Check all the method declarations. */ > check_methods (t); > diff --git a/gcc/testsuite/g++.dg/cpp2a/concepts-dtor1.C b/gcc/testsuite/g++.dg/cpp2a/concepts-dtor1.C > new file mode 100644 > index 00000000000..b1f3b4e579f > --- /dev/null > +++ b/gcc/testsuite/g++.dg/cpp2a/concepts-dtor1.C > @@ -0,0 +1,18 @@ > +// PR c++/96745 > +// { dg-do compile { target c++20 } } > + > +template<class T> > +struct A { // { dg-error "destructor for 'A<int>' is ambiguous" } > + ~A() requires true; > + ~A() requires (!!true); > +}; > + > +A<int> a; > + > +template<class T> > +struct B { // { dg-error "no viable destructor for 'B<int>'" } > + ~B() requires false; > + ~B() requires (!!false); > +}; > + > +B<int> b;
diff --git a/gcc/cp/class.cc b/gcc/cp/class.cc index d3ce8532d56..c6878cba2ae 100644 --- a/gcc/cp/class.cc +++ b/gcc/cp/class.cc @@ -4808,9 +4808,23 @@ check_methods (tree t) in that class with an empty argument list to select the destructor for the class, also known as the selected destructor. The program is ill-formed if overload resolution fails. */ + int viable = 0; + for (tree fn : ovl_range (dtor)) + if (constraints_satisfied_p (fn)) + ++viable; + gcc_checking_assert (viable != 1); + auto_diagnostic_group d; - error_at (location_of (t), "destructor for %qT is ambiguous", t); + if (viable == 0) + error_at (location_of (t), "no viable destructor for %qT", t); + else + error_at (location_of (t), "destructor for %qT is ambiguous", t); print_candidates (dtor); + + /* Arbitrarily prune the overload set to a single function for + sake of error recovery. */ + tree *slot = find_member_slot (t, dtor_identifier); + *slot = get_first_fn (dtor); } else if (user_provided_p (dtor)) TYPE_HAS_NONTRIVIAL_DESTRUCTOR (t) = true; @@ -6048,10 +6062,12 @@ check_bases_and_members (tree t) check_bases (t, &cant_have_const_ctor, &no_const_asn_ref); /* Deduce noexcept on destructor. This needs to happen after we've set - triviality flags appropriately for our bases. */ + triviality flags appropriately for our bases, and before checking + overriden virtual functions via check_methods. */ if (cxx_dialect >= cxx11) if (tree dtor = CLASSTYPE_DESTRUCTOR (t)) - deduce_noexcept_on_destructor (dtor); + for (tree fn : ovl_range (dtor)) + deduce_noexcept_on_destructor (fn); /* Check all the method declarations. */ check_methods (t); diff --git a/gcc/testsuite/g++.dg/cpp2a/concepts-dtor1.C b/gcc/testsuite/g++.dg/cpp2a/concepts-dtor1.C new file mode 100644 index 00000000000..b1f3b4e579f --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp2a/concepts-dtor1.C @@ -0,0 +1,18 @@ +// PR c++/96745 +// { dg-do compile { target c++20 } } + +template<class T> +struct A { // { dg-error "destructor for 'A<int>' is ambiguous" } + ~A() requires true; + ~A() requires (!!true); +}; + +A<int> a; + +template<class T> +struct B { // { dg-error "no viable destructor for 'B<int>'" } + ~B() requires false; + ~B() requires (!!false); +}; + +B<int> b;