| Message ID | 20240206215955.4107411-1-ppalka@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | c++: NTTP type CTAD w/ tmpl from current inst [PR113649] | expand |
On 2/6/24 16:59, Patrick Palka wrote: > Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK > for trunk? > > -- >8 -- > > Since template argument coercion happens relative to the most general > template (for a class template at least), during NTTP type CTAD we might > need to consider outer arguments particularly if the CTAD template is from > the current instantiation (and so depends on outer template parameters). > > This patch makes do_class_deduction substitute as many levels of outer > template arguments into a CTAD template (from the current instantiation) > as it can take. I guess that's a reasonable way to communicate outer_args to ctor_deduction_guides_for. OK. > PR c++/113649 > > gcc/cp/ChangeLog: > > * pt.cc (do_class_deduction): Add outer_targs parameter. > Substitute outer arguments into the CTAD template. > (do_auto_deduction): Pass outer_targs to do_class_deduction. > > gcc/testsuite/ChangeLog: > > * g++.dg/cpp2a/nontype-class64.C: New test. > --- > gcc/cp/pt.cc | 21 ++++++++++++++++++-- > gcc/testsuite/g++.dg/cpp2a/nontype-class64.C | 16 +++++++++++++++ > 2 files changed, 35 insertions(+), 2 deletions(-) > create mode 100644 gcc/testsuite/g++.dg/cpp2a/nontype-class64.C > > diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc > index 903a4a1c363..83c3b1920d6 100644 > --- a/gcc/cp/pt.cc > +++ b/gcc/cp/pt.cc > @@ -30681,7 +30681,7 @@ ctad_template_p (tree tmpl) > type. */ > > static tree > -do_class_deduction (tree ptype, tree tmpl, tree init, > +do_class_deduction (tree ptype, tree tmpl, tree init, tree outer_targs, > int flags, tsubst_flags_t complain) > { > /* We should have handled this in the caller. */ > @@ -30743,6 +30743,23 @@ do_class_deduction (tree ptype, tree tmpl, tree init, > if (type_dependent_expression_p (init)) > return ptype; > > + if (outer_targs) > + { > + int args_depth = TMPL_ARGS_DEPTH (outer_targs); > + int parms_depth = TMPL_PARMS_DEPTH (DECL_TEMPLATE_PARMS (tmpl)); > + if (parms_depth > 1) > + { > + /* Substitute outer arguments into this CTAD template from the > + current instantiation. */ > + int want = std::min (args_depth, parms_depth - 1); > + outer_targs = strip_innermost_template_args (outer_targs, > + args_depth - want); > + tmpl = tsubst (tmpl, outer_targs, complain, NULL_TREE); > + if (tmpl == error_mark_node) > + return error_mark_node; > + } > + } > + > /* Don't bother with the alias rules for an equivalent template. */ > tmpl = get_underlying_template (tmpl); > > @@ -30998,7 +31015,7 @@ do_auto_deduction (tree type, tree init, tree auto_node, > > if (tree ctmpl = CLASS_PLACEHOLDER_TEMPLATE (auto_node)) > /* C++17 class template argument deduction. */ > - return do_class_deduction (type, ctmpl, init, flags, complain); > + return do_class_deduction (type, ctmpl, init, outer_targs, flags, complain); > > if (init == NULL_TREE || TREE_TYPE (init) == NULL_TREE) > /* Nothing we can do with this, even in deduction context. */ > diff --git a/gcc/testsuite/g++.dg/cpp2a/nontype-class64.C b/gcc/testsuite/g++.dg/cpp2a/nontype-class64.C > new file mode 100644 > index 00000000000..8397ea5a886 > --- /dev/null > +++ b/gcc/testsuite/g++.dg/cpp2a/nontype-class64.C > @@ -0,0 +1,16 @@ > +// PR c++/113649 > +// { dg-do compile { target c++20 } } > + > +template<class... Args> > +struct A { > + template<class Ret> > + struct Fun { constexpr Fun(Ret(*)(Args...)) { } }; > + > + template<Fun f> > + struct B { using type = decltype(f); }; > +}; > + > +bool f(char, long); > + > +using type = A<char, long>::B<&f>::type; > +using type = A<char, long>::Fun<bool>;
diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc index 903a4a1c363..83c3b1920d6 100644 --- a/gcc/cp/pt.cc +++ b/gcc/cp/pt.cc @@ -30681,7 +30681,7 @@ ctad_template_p (tree tmpl) type. */ static tree -do_class_deduction (tree ptype, tree tmpl, tree init, +do_class_deduction (tree ptype, tree tmpl, tree init, tree outer_targs, int flags, tsubst_flags_t complain) { /* We should have handled this in the caller. */ @@ -30743,6 +30743,23 @@ do_class_deduction (tree ptype, tree tmpl, tree init, if (type_dependent_expression_p (init)) return ptype; + if (outer_targs) + { + int args_depth = TMPL_ARGS_DEPTH (outer_targs); + int parms_depth = TMPL_PARMS_DEPTH (DECL_TEMPLATE_PARMS (tmpl)); + if (parms_depth > 1) + { + /* Substitute outer arguments into this CTAD template from the + current instantiation. */ + int want = std::min (args_depth, parms_depth - 1); + outer_targs = strip_innermost_template_args (outer_targs, + args_depth - want); + tmpl = tsubst (tmpl, outer_targs, complain, NULL_TREE); + if (tmpl == error_mark_node) + return error_mark_node; + } + } + /* Don't bother with the alias rules for an equivalent template. */ tmpl = get_underlying_template (tmpl); @@ -30998,7 +31015,7 @@ do_auto_deduction (tree type, tree init, tree auto_node, if (tree ctmpl = CLASS_PLACEHOLDER_TEMPLATE (auto_node)) /* C++17 class template argument deduction. */ - return do_class_deduction (type, ctmpl, init, flags, complain); + return do_class_deduction (type, ctmpl, init, outer_targs, flags, complain); if (init == NULL_TREE || TREE_TYPE (init) == NULL_TREE) /* Nothing we can do with this, even in deduction context. */ diff --git a/gcc/testsuite/g++.dg/cpp2a/nontype-class64.C b/gcc/testsuite/g++.dg/cpp2a/nontype-class64.C new file mode 100644 index 00000000000..8397ea5a886 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp2a/nontype-class64.C @@ -0,0 +1,16 @@ +// PR c++/113649 +// { dg-do compile { target c++20 } } + +template<class... Args> +struct A { + template<class Ret> + struct Fun { constexpr Fun(Ret(*)(Args...)) { } }; + + template<Fun f> + struct B { using type = decltype(f); }; +}; + +bool f(char, long); + +using type = A<char, long>::B<&f>::type; +using type = A<char, long>::Fun<bool>;