From 43c013df02fdb07f9b7a5e7e6669e6d69769d451 Mon Sep 17 00:00:00 2001 From: Patrick Palka Date: Fri, 3 Jun 2022 09:29:12 -0400 Subject: [PATCH] c++: don't substitute TEMPLATE_PARM_CONSTRAINTS [PR100374] This patch makes us avoid substituting into the TEMPLATE_PARM_CONSTRAINTS of each template parameter except as necessary for declaration matching, like we already do for the other constituent constraints of a declaration. This patch also improves the CA104 implementation of explicit specialization matching of a constrained function template inside a class template, by considering the function's combined constraints instead of just its trailing constraints. This allows us to correctly handle the first three explicit specializations in concepts-spec2.C below, but because we compare the constraints as a whole, it means we incorrectly accept the fourth explicit specialization which writes #3's constraints in a different way. For complete correctness here, determine_specialization should use tsubst_each_template_parm_constraints and template_parameter_heads_equivalent_p. PR c++/100374 gcc/cp/ChangeLog: * pt.cc (determine_specialization): Compare overall constraints not just the trailing constraints. (tsubst_each_template_parm_constraints): Define. (tsubst_friend_function): Use it. (tsubst_friend_class): Use it. (tsubst_template_parm): Don't substitute TEMPLATE_PARM_CONSTRAINTS. gcc/testsuite/ChangeLog: * g++.dg/cpp2a/concepts-spec2.C: New test. * g++.dg/cpp2a/concepts-template-parm11.C: New test. --- gcc/cp/pt.cc | 42 ++++++++++++++++++---- gcc/testsuite/g++.dg/cpp2a/concepts-spec2.C | 16 +++++++++ .../g++.dg/cpp2a/concepts-template-parm11.C | 20 +++++++++++ 3 files changed, 71 insertions(+), 7 deletions(-) create mode 100644 gcc/testsuite/g++.dg/cpp2a/concepts-spec2.C create mode 100644 gcc/testsuite/g++.dg/cpp2a/concepts-template-parm11.C diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc index d0c4c98..59b9431 100644 --- a/gcc/cp/pt.cc +++ b/gcc/cp/pt.cc @@ -184,6 +184,7 @@ static int unify_pack_expansion (tree, tree, tree, tree, unification_kind_t, bool, bool); static tree copy_template_args (tree); static tree tsubst_template_parms (tree, tree, tsubst_flags_t); +static void tsubst_each_template_parm_constraints (tree, tree, tsubst_flags_t); tree most_specialized_partial_spec (tree, tsubst_flags_t); static tree tsubst_aggr_type (tree, tree, tsubst_flags_t, tree, int); static tree tsubst_arg_types (tree, tree, tree, tsubst_flags_t, tree); @@ -2323,8 +2324,8 @@ determine_specialization (tree template_id, if (!compparms (fn_arg_types, decl_arg_types)) continue; - tree freq = get_trailing_function_requirements (fn); - tree dreq = get_trailing_function_requirements (decl); + tree freq = get_constraints (fn); + tree dreq = get_constraints (decl); if (!freq != !dreq) continue; if (freq) @@ -2333,7 +2334,7 @@ determine_specialization (tree template_id, constraint-expression. */ tree fargs = DECL_TI_ARGS (fn); tsubst_flags_t complain = tf_none; - freq = tsubst_constraint (freq, fargs, complain, fn); + freq = tsubst_constraint_info (freq, fargs, complain, fn); if (!cp_tree_equal (freq, dreq)) continue; } @@ -11240,7 +11241,13 @@ tsubst_friend_function (tree decl, tree args) tree parms = DECL_TEMPLATE_PARMS (new_friend); tree treqs = TEMPLATE_PARMS_CONSTRAINTS (parms); treqs = maybe_substitute_reqs_for (treqs, new_friend); - TEMPLATE_PARMS_CONSTRAINTS (parms) = treqs; + if (treqs != TEMPLATE_PARMS_CONSTRAINTS (parms)) + { + TEMPLATE_PARMS_CONSTRAINTS (parms) = treqs; + /* As well as each TEMPLATE_PARM_CONSTRAINTS. */ + tsubst_each_template_parm_constraints (parms, args, + tf_warning_or_error); + } } /* The mangled name for the NEW_FRIEND is incorrect. The function @@ -11486,6 +11493,8 @@ tsubst_friend_class (tree friend_tmpl, tree args) { tree parms = tsubst_template_parms (DECL_TEMPLATE_PARMS (friend_tmpl), args, tf_warning_or_error); + tsubst_each_template_parm_constraints (parms, args, + tf_warning_or_error); location_t saved_input_location = input_location; input_location = DECL_SOURCE_LOCATION (friend_tmpl); tree cons = get_constraints (tmpl); @@ -11520,6 +11529,8 @@ tsubst_friend_class (tree friend_tmpl, tree args) DECL_FRIEND_CONTEXT (friend_tmpl)); --processing_template_decl; set_constraints (tmpl, ci); + tsubst_each_template_parm_constraints (DECL_TEMPLATE_PARMS (tmpl), + args, tf_warning_or_error); } /* Inject this template into the enclosing namspace scope. */ @@ -13632,7 +13643,6 @@ tsubst_template_parm (tree t, tree args, tsubst_flags_t complain) default_value = TREE_PURPOSE (t); parm_decl = TREE_VALUE (t); - tree constraint = TEMPLATE_PARM_CONSTRAINTS (t); parm_decl = tsubst (parm_decl, args, complain, NULL_TREE); if (TREE_CODE (parm_decl) == PARM_DECL @@ -13640,13 +13650,31 @@ tsubst_template_parm (tree t, tree args, tsubst_flags_t complain) parm_decl = error_mark_node; default_value = tsubst_template_arg (default_value, args, complain, NULL_TREE); - constraint = tsubst_constraint (constraint, args, complain, NULL_TREE); tree r = build_tree_list (default_value, parm_decl); - TEMPLATE_PARM_CONSTRAINTS (r) = constraint; + TEMPLATE_PARM_CONSTRAINTS (r) = TEMPLATE_PARM_CONSTRAINTS (t); return r; } +/* Substitute in-place the TEMPLATE_PARM_CONSTRAINTS of each template + parameter in PARMS for sake of declaration matching. */ + +static void +tsubst_each_template_parm_constraints (tree parms, tree args, + tsubst_flags_t complain) +{ + ++processing_template_decl; + for (; parms; parms = TREE_CHAIN (parms)) + { + tree level = TREE_VALUE (parms); + for (tree parm : tree_vec_range (level)) + TEMPLATE_PARM_CONSTRAINTS (parm) + = tsubst_constraint (TEMPLATE_PARM_CONSTRAINTS (parm), args, + complain, NULL_TREE); + } + --processing_template_decl; +} + /* Substitute the ARGS into the indicated aggregate (or enumeration) type T. If T is not an aggregate or enumeration type, it is handled as if by tsubst. IN_DECL is as for tsubst. If diff --git a/gcc/testsuite/g++.dg/cpp2a/concepts-spec2.C b/gcc/testsuite/g++.dg/cpp2a/concepts-spec2.C new file mode 100644 index 0000000..4de0735 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp2a/concepts-spec2.C @@ -0,0 +1,16 @@ +// { dg-do compile { target c++20 } } + +template concept C = true; + +template struct A { + template U> void f(); // #1 + template U> void f(); // #2 + template U> void f(); // #3 +}; + +constexpr int n = sizeof(int); +template<> template U> void A::f() { } // matches #1 +template<> template U> void A::f() { } // matches #2 +template<> template U> void A::f() { } // no match { dg-error "match" } +template<> template void A::f() requires C { } // shouldn't match #3 +// { dg-error "match" "" { xfail *-*-* } .-1 } diff --git a/gcc/testsuite/g++.dg/cpp2a/concepts-template-parm11.C b/gcc/testsuite/g++.dg/cpp2a/concepts-template-parm11.C new file mode 100644 index 0000000..498e3c1 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp2a/concepts-template-parm11.C @@ -0,0 +1,20 @@ +// PR c++/100374 +// { dg-do compile { target c++20 } } + +template +concept C = requires { typename T; }; + +template +struct A { + template U> + void f(); + + template U> + struct B; +}; + +int main() { + A a; + a.f(); + using type = A::B; +} -- 2.7.4