This makes us avoid substituting into the TEMPLATE_PARM_CONSTRAINT of
each template parameter except as necessary for (friend) declaration
matching, like we already do for the overall TEMPLATE_PARMS_CONSTRAINTS
of a template parameter list.
Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK for
trunk and perhaps 12.2? Also tested on range-v3 and cmcstl2.
PR c++/100374
gcc/cp/ChangeLog:
* pt.cc (tsubst_each_template_parm_constraint): Define.
(tsubst_friend_function): Use it.
(tsubst_friend_class): Use it.
(tsubst_template_parm): Don't substitute TEMPLATE_PARM_CONSTRAINT.
gcc/testsuite/ChangeLog:
* g++.dg/cpp2a/concepts-template-parm11.C: New test.
---
gcc/cp/pt.cc | 35 ++++++++++++++++---
.../g++.dg/cpp2a/concepts-template-parm11.C | 16 +++++++++
2 files changed, 47 insertions(+), 4 deletions(-)
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 24bbe2f4060..ec168234325 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_constraint (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);
@@ -11254,7 +11255,12 @@ 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_CONSTRAINT. */
+ tsubst_each_template_parm_constraint (parms, args,
tf_warning_or_error);
+ }
}
/* The mangled name for the NEW_FRIEND is incorrect. The function
@@ -11500,6 +11506,8 @@ 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_constraint (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);
@@ -11534,6 +11542,8 @@ tsubst_friend_class (tree friend_tmpl, tree args)
DECL_FRIEND_CONTEXT (friend_tmpl));
--processing_template_decl;
set_constraints (tmpl, ci);
+ tsubst_each_template_parm_constraint (DECL_TEMPLATE_PARMS (tmpl),
+ args, tf_warning_or_error);
}
/* Inject this template into the enclosing namspace scope. */
@@ -13656,7 +13666,6 @@ 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
@@ -13664,13 +13673,31 @@ 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_CONSTRAINT of each template
+ parameter in PARMS for sake of declaration matching. */
+
+static void
+tsubst_each_template_parm_constraint (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-template-parm11.C
b/gcc/testsuite/g++.dg/cpp2a/concepts-template-parm11.C
new file mode 100644
index 00000000000..f70de341a07
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp2a/concepts-template-parm11.C
@@ -0,0 +1,16 @@
+// PR c++/100374
+// { dg-do compile { target c++20 } }
+
+template<class T, class U>
+concept C = true;
+
+template<class T>
+struct A {
+ template<C<typename T::value_type> U>
+ void f();
+
+ template<C<typename T::value_type> U>
+ struct B;
+};
+
+template struct A<float>;
--
2.36.1.195.g8ddf593a25
