| Message ID | 20220721124357.284497-1-ppalka@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | c++: CTAD from initializer list [PR106366] | expand |
On Thu, 21 Jul 2022, Patrick Palka wrote: > During CTAD, we currently perform the first phase of overload resolution > from [over.match.list] only if the class template has a list constructor. > But according to [over.match.class.deduct]/4 it should be enough to just > have a guide that looks like a list constructor (which is a more general > criterion in light of user-defined guides). > > Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK for > trunk? > > PR c++/106366 > > gcc/cp/ChangeLog: > > * pt.cc (do_class_deduction): Don't consider TYPE_HAS_LIST_CTOR > when setting try_list_ctor. Reset args even when try_list_ctor > is true and there are no list candidates. Call resolve_args on > the reset args. > > gcc/testsuite/ChangeLog: > > * g++.dg/cpp1z/class-deduction112.C: New test. > --- > gcc/cp/pt.cc | 25 +++++++++---------- > .../g++.dg/cpp1z/class-deduction112.C | 14 +++++++++++ > 2 files changed, 26 insertions(+), 13 deletions(-) > create mode 100644 gcc/testsuite/g++.dg/cpp1z/class-deduction112.C > > diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc > index 718dfa5bfa8..0f26d6f5bce 100644 > --- a/gcc/cp/pt.cc > +++ b/gcc/cp/pt.cc > @@ -30250,8 +30250,8 @@ do_class_deduction (tree ptype, tree tmpl, tree init, > else if (BRACE_ENCLOSED_INITIALIZER_P (init)) > { > list_init_p = true; > - try_list_ctor = TYPE_HAS_LIST_CTOR (type); > - if (try_list_ctor && CONSTRUCTOR_NELTS (init) == 1 > + try_list_ctor = true; I suppose try_list_cand would be a more appropriate name for this variable now, consider that fixed. > + if (CONSTRUCTOR_NELTS (init) == 1 > && !CONSTRUCTOR_IS_DESIGNATED_INIT (init)) > { > /* As an exception, the first phase in 16.3.1.7 (considering the > @@ -30310,26 +30310,25 @@ do_class_deduction (tree ptype, tree tmpl, tree init, > > tree fndecl = error_mark_node; > > - /* If this is list-initialization and the class has a list constructor, first > + /* If this is list-initialization and the class has a list guide, first > try deducing from the list as a single argument, as [over.match.list]. */ > - tree list_cands = NULL_TREE; > - if (try_list_ctor && cands) > - for (lkp_iterator iter (cands); iter; ++iter) > - { > - tree dg = *iter; > + if (try_list_ctor) > + { > + tree list_cands = NULL_TREE; > + for (tree dg : lkp_range (cands)) > if (is_list_ctor (dg)) > list_cands = lookup_add (dg, list_cands); > - } > - if (list_cands) > - { > - fndecl = perform_dguide_overload_resolution (list_cands, args, tf_none); > - > + if (list_cands) > + fndecl = perform_dguide_overload_resolution (list_cands, args, tf_none); > if (fndecl == error_mark_node) > { > /* That didn't work, now try treating the list as a sequence of > arguments. */ > release_tree_vector (args); > args = make_tree_vector_from_ctor (init); > + args = resolve_args (args, complain); > + if (args == NULL) > + return error_mark_node; > } > } > > diff --git a/gcc/testsuite/g++.dg/cpp1z/class-deduction112.C b/gcc/testsuite/g++.dg/cpp1z/class-deduction112.C > new file mode 100644 > index 00000000000..8da5868ff98 > --- /dev/null > +++ b/gcc/testsuite/g++.dg/cpp1z/class-deduction112.C > @@ -0,0 +1,14 @@ > +// PR c++/106366 > +// { dg-do compile { target c++17 } } > + > +#include <initializer_list> > + > +template<class T> > +struct A { A(...); }; > + > +template<typename T> > +A(std::initializer_list<T>) -> A<T>; > + > +A a{1,2,3}; > +using type = decltype(a); > +using type = A<int>; > -- > 2.37.1.208.ge72d93e88c > >
On 7/21/22 08:43, Patrick Palka wrote: > During CTAD, we currently perform the first phase of overload resolution > from [over.match.list] only if the class template has a list constructor. > But according to [over.match.class.deduct]/4 it should be enough to just > have a guide that looks like a list constructor (which is a more general > criterion in light of user-defined guides). > > Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK for > trunk? OK. > PR c++/106366 > > gcc/cp/ChangeLog: > > * pt.cc (do_class_deduction): Don't consider TYPE_HAS_LIST_CTOR > when setting try_list_ctor. Reset args even when try_list_ctor > is true and there are no list candidates. Call resolve_args on > the reset args. > > gcc/testsuite/ChangeLog: > > * g++.dg/cpp1z/class-deduction112.C: New test. > --- > gcc/cp/pt.cc | 25 +++++++++---------- > .../g++.dg/cpp1z/class-deduction112.C | 14 +++++++++++ > 2 files changed, 26 insertions(+), 13 deletions(-) > create mode 100644 gcc/testsuite/g++.dg/cpp1z/class-deduction112.C > > diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc > index 718dfa5bfa8..0f26d6f5bce 100644 > --- a/gcc/cp/pt.cc > +++ b/gcc/cp/pt.cc > @@ -30250,8 +30250,8 @@ do_class_deduction (tree ptype, tree tmpl, tree init, > else if (BRACE_ENCLOSED_INITIALIZER_P (init)) > { > list_init_p = true; > - try_list_ctor = TYPE_HAS_LIST_CTOR (type); > - if (try_list_ctor && CONSTRUCTOR_NELTS (init) == 1 > + try_list_ctor = true; > + if (CONSTRUCTOR_NELTS (init) == 1 > && !CONSTRUCTOR_IS_DESIGNATED_INIT (init)) > { > /* As an exception, the first phase in 16.3.1.7 (considering the > @@ -30310,26 +30310,25 @@ do_class_deduction (tree ptype, tree tmpl, tree init, > > tree fndecl = error_mark_node; > > - /* If this is list-initialization and the class has a list constructor, first > + /* If this is list-initialization and the class has a list guide, first > try deducing from the list as a single argument, as [over.match.list]. */ > - tree list_cands = NULL_TREE; > - if (try_list_ctor && cands) > - for (lkp_iterator iter (cands); iter; ++iter) > - { > - tree dg = *iter; > + if (try_list_ctor) > + { > + tree list_cands = NULL_TREE; > + for (tree dg : lkp_range (cands)) > if (is_list_ctor (dg)) > list_cands = lookup_add (dg, list_cands); > - } > - if (list_cands) > - { > - fndecl = perform_dguide_overload_resolution (list_cands, args, tf_none); > - > + if (list_cands) > + fndecl = perform_dguide_overload_resolution (list_cands, args, tf_none); > if (fndecl == error_mark_node) > { > /* That didn't work, now try treating the list as a sequence of > arguments. */ > release_tree_vector (args); > args = make_tree_vector_from_ctor (init); > + args = resolve_args (args, complain); > + if (args == NULL) > + return error_mark_node; > } > } > > diff --git a/gcc/testsuite/g++.dg/cpp1z/class-deduction112.C b/gcc/testsuite/g++.dg/cpp1z/class-deduction112.C > new file mode 100644 > index 00000000000..8da5868ff98 > --- /dev/null > +++ b/gcc/testsuite/g++.dg/cpp1z/class-deduction112.C > @@ -0,0 +1,14 @@ > +// PR c++/106366 > +// { dg-do compile { target c++17 } } > + > +#include <initializer_list> > + > +template<class T> > +struct A { A(...); }; > + > +template<typename T> > +A(std::initializer_list<T>) -> A<T>; > + > +A a{1,2,3}; > +using type = decltype(a); > +using type = A<int>;
diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc index 718dfa5bfa8..0f26d6f5bce 100644 --- a/gcc/cp/pt.cc +++ b/gcc/cp/pt.cc @@ -30250,8 +30250,8 @@ do_class_deduction (tree ptype, tree tmpl, tree init, else if (BRACE_ENCLOSED_INITIALIZER_P (init)) { list_init_p = true; - try_list_ctor = TYPE_HAS_LIST_CTOR (type); - if (try_list_ctor && CONSTRUCTOR_NELTS (init) == 1 + try_list_ctor = true; + if (CONSTRUCTOR_NELTS (init) == 1 && !CONSTRUCTOR_IS_DESIGNATED_INIT (init)) { /* As an exception, the first phase in 16.3.1.7 (considering the @@ -30310,26 +30310,25 @@ do_class_deduction (tree ptype, tree tmpl, tree init, tree fndecl = error_mark_node; - /* If this is list-initialization and the class has a list constructor, first + /* If this is list-initialization and the class has a list guide, first try deducing from the list as a single argument, as [over.match.list]. */ - tree list_cands = NULL_TREE; - if (try_list_ctor && cands) - for (lkp_iterator iter (cands); iter; ++iter) - { - tree dg = *iter; + if (try_list_ctor) + { + tree list_cands = NULL_TREE; + for (tree dg : lkp_range (cands)) if (is_list_ctor (dg)) list_cands = lookup_add (dg, list_cands); - } - if (list_cands) - { - fndecl = perform_dguide_overload_resolution (list_cands, args, tf_none); - + if (list_cands) + fndecl = perform_dguide_overload_resolution (list_cands, args, tf_none); if (fndecl == error_mark_node) { /* That didn't work, now try treating the list as a sequence of arguments. */ release_tree_vector (args); args = make_tree_vector_from_ctor (init); + args = resolve_args (args, complain); + if (args == NULL) + return error_mark_node; } } diff --git a/gcc/testsuite/g++.dg/cpp1z/class-deduction112.C b/gcc/testsuite/g++.dg/cpp1z/class-deduction112.C new file mode 100644 index 00000000000..8da5868ff98 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp1z/class-deduction112.C @@ -0,0 +1,14 @@ +// PR c++/106366 +// { dg-do compile { target c++17 } } + +#include <initializer_list> + +template<class T> +struct A { A(...); }; + +template<typename T> +A(std::initializer_list<T>) -> A<T>; + +A a{1,2,3}; +using type = decltype(a); +using type = A<int>;