https://gcc.gnu.org/g:57cd8665fea4c339369a43be017583621aa82fed
commit r14-10201-g57cd8665fea4c339369a43be017583621aa82fed Author: Patrick Palka <ppa...@redhat.com> Date: Mon May 13 09:53:40 2024 -0400 c++: nested aggregate/alias CTAD fixes [PR114974, PR114901, PR114903] During maybe_aggr_guide with a nested class template and paren init, like with list init we need to consider the generic template type rather than the partially instantiated type since partial instantiations don't have (partially instantiated) TYPE_FIELDS. In turn we need to partially substitute PARMs in the paren init case as well. As a drive-by improvement it seems better to use outer_template_args instead of DECL_TI_ARGS during this partial substitution so that we lower instead of substitute the innermost template parameters, which is generally more robust. And during alias_ctad_tweaks with a nested class template, even though the guides may be already partially instantiated we still need to substitute the outermost arguments into its constraints. PR c++/114974 PR c++/114901 PR c++/114903 gcc/cp/ChangeLog: * pt.cc (maybe_aggr_guide): Fix obtaining TYPE_FIELDS in the paren init case. Hoist out partial substitution logic to apply to the paren init case as well. (alias_ctad_tweaks): Substitute outer template arguments into a guide's constraints. gcc/testsuite/ChangeLog: * g++.dg/cpp2a/class-deduction-aggr14.C: New test. * g++.dg/cpp2a/class-deduction-alias20.C: New test. * g++.dg/cpp2a/class-deduction-alias21.C: New test. Reviewed-by: Jason Merrill <ja...@redhat.com> (cherry picked from commit 6d31a370e26eeb950c326332633b3e8e84b6630b) Diff: --- gcc/cp/pt.cc | 39 ++++++++++++---------- .../g++.dg/cpp2a/class-deduction-aggr14.C | 11 ++++++ .../g++.dg/cpp2a/class-deduction-alias20.C | 22 ++++++++++++ .../g++.dg/cpp2a/class-deduction-alias21.C | 38 +++++++++++++++++++++ 4 files changed, 93 insertions(+), 17 deletions(-) diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc index 3b2106dd3f65..b5c494e8d15e 100644 --- a/gcc/cp/pt.cc +++ b/gcc/cp/pt.cc @@ -30201,26 +30201,11 @@ maybe_aggr_guide (tree tmpl, tree init, vec<tree,va_gc> *args) if (init == error_mark_node) return NULL_TREE; parms = collect_ctor_idx_types (init, parms); - /* If we're creating a deduction guide for a member class template, - we've used the original template pattern type for the reshape_init - above; this is done because we want PARMS to be a template parameter - type, something that can be deduced when used as a function template - parameter. At this point the outer class template has already been - partially instantiated (we deferred the deduction until the enclosing - scope is non-dependent). Therefore we have to partially instantiate - PARMS, so that its template level is properly reduced and we don't get - mismatches when deducing types using the guide with PARMS. */ - if (member_template_p) - { - ++processing_template_decl; - parms = tsubst (parms, DECL_TI_ARGS (tmpl), complain, init); - --processing_template_decl; - } } else if (TREE_CODE (init) == TREE_LIST) { int len = list_length (init); - for (tree field = TYPE_FIELDS (type); + for (tree field = TYPE_FIELDS (template_type); len; --len, field = DECL_CHAIN (field)) { @@ -30235,6 +30220,22 @@ maybe_aggr_guide (tree tmpl, tree init, vec<tree,va_gc> *args) /* Aggregate initialization doesn't apply to an initializer expression. */ return NULL_TREE; + /* If we're creating a deduction guide for a member class template, + we've used the original template pattern type for the reshape_init + above; this is done because we want PARMS to be a template parameter + type, something that can be deduced when used as a function template + parameter. At this point the outer class template has already been + partially instantiated (we deferred the deduction until the enclosing + scope is non-dependent). Therefore we have to partially instantiate + PARMS, so that its template level is properly reduced and we don't get + mismatches when deducing types using the guide with PARMS. */ + if (member_template_p) + { + ++processing_template_decl; + parms = tsubst (parms, outer_template_args (tmpl), complain, init); + --processing_template_decl; + } + if (parms) { tree last = parms; @@ -30426,7 +30427,11 @@ alias_ctad_tweaks (tree tmpl, tree uguides) /* Substitute the associated constraints. */ tree ci = get_constraints (f); if (ci) - ci = tsubst_constraint_info (ci, targs, complain, in_decl); + { + if (tree outer_targs = outer_template_args (f)) + ci = tsubst_constraint_info (ci, outer_targs, complain, in_decl); + ci = tsubst_constraint_info (ci, targs, complain, in_decl); + } if (ci == error_mark_node) continue; diff --git a/gcc/testsuite/g++.dg/cpp2a/class-deduction-aggr14.C b/gcc/testsuite/g++.dg/cpp2a/class-deduction-aggr14.C new file mode 100644 index 000000000000..de636eb84e06 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp2a/class-deduction-aggr14.C @@ -0,0 +1,11 @@ +// PR c++/114974 +// { dg-do compile { target c++20 } } + +template<typename T1> +struct A { + template<typename T2> + struct B { T2 t; }; +}; + +A<int>::B x{2}; // OK +A<int>::B y(2); // OK, previously rejected diff --git a/gcc/testsuite/g++.dg/cpp2a/class-deduction-alias20.C b/gcc/testsuite/g++.dg/cpp2a/class-deduction-alias20.C new file mode 100644 index 000000000000..8cc56d91e370 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp2a/class-deduction-alias20.C @@ -0,0 +1,22 @@ +// PR c++/114901 +// { dg-do compile { target c++20 } } + +template <class D> +constexpr bool C = sizeof(D); + +template <typename U> +struct T { + template<typename V, typename N> + struct Foo { + Foo(V, N); + }; + + template<typename X, typename N> + requires (C<N>) // removes the require-clause will make the crash disappear + Foo(X, N) -> Foo<X, N>; + + template <typename Y, typename Y2, int N = sizeof(Y2)> + using AFoo = Foo<decltype(N), Y2>; +}; + +T<double>::AFoo s{1, 2}; // { dg-error "deduction|no match" } diff --git a/gcc/testsuite/g++.dg/cpp2a/class-deduction-alias21.C b/gcc/testsuite/g++.dg/cpp2a/class-deduction-alias21.C new file mode 100644 index 000000000000..c39a0f9f1416 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp2a/class-deduction-alias21.C @@ -0,0 +1,38 @@ +// PR c++/114903 +// { dg-do compile { target c++20 } } + +template <typename T> +struct Key { + Key(int); +}; + +class Forward {}; + +template <typename T> +constexpr bool C = __is_same(T, Forward); + +template <typename Z> +struct Outer { + template <typename U> + struct Foo { + Foo(U); + U u; + }; + + template <typename V> + requires(C<Z>) + Foo(V) -> Foo<int>; +}; + +template <typename Y> +struct T { + template <typename Y2> + struct T2 { + template <typename K> + using AFoo = Outer<Y2>::template Foo<K>; + }; +}; + +T<Forward>::T2<Forward>::AFoo a(1.0); +using type = decltype(a); +using type = Outer<Forward>::Foo<int>;