On 9/16/21 09:11, Patrick Palka wrote:
This fixes some issues with constrained variable templates:
* Constraints aren't checked when explicitly specializing a variable
template
* Constraints aren't attached to a static data member template at
parse time
* Constraints aren't propagated when (partially) instantiating a
static data member template
Bootstrapped and regtested on x86_64-pc-linux-gnu, and also tested on
cmcstl2 and range-v3, does this look OK for trunk and perhaps 11?
PR c++/98486
gcc/cp/ChangeLog:
* decl.c (grokdeclarator): Set constraints on a static data
member template.
* pt.c (determine_specialization): Check constraints on a
variable template.
These hunks are OK.
(tsubst_decl) <case VAR_DECL>: Propagate constraints on a
static data member template.
Hmm, why is this necessary? I know we already do this for functions,
but I don't remember why. Don't we check satisfaction for the
most-general template?
gcc/testsuite/ChangeLog:
* g++.dg/cpp2a/concepts-var-templ1.C: New test.
* g++.dg/cpp2a/concepts-var-templ1a.C: New test.
* g++.dg/cpp2a/concepts-var-templ1b.C: New test.
---
gcc/cp/decl.c | 11 +++++++++++
gcc/cp/pt.c | 8 +++++++-
gcc/testsuite/g++.dg/cpp2a/concepts-var-templ1.C | 9 +++++++++
gcc/testsuite/g++.dg/cpp2a/concepts-var-templ1a.C | 14 ++++++++++++++
gcc/testsuite/g++.dg/cpp2a/concepts-var-templ1b.C | 15 +++++++++++++++
5 files changed, 56 insertions(+), 1 deletion(-)
create mode 100644 gcc/testsuite/g++.dg/cpp2a/concepts-var-templ1.C
create mode 100644 gcc/testsuite/g++.dg/cpp2a/concepts-var-templ1a.C
create mode 100644 gcc/testsuite/g++.dg/cpp2a/concepts-var-templ1b.C
diff --git a/gcc/cp/decl.c b/gcc/cp/decl.c
index c0f1496636f..7beac79ec25 100644
--- a/gcc/cp/decl.c
+++ b/gcc/cp/decl.c
@@ -13980,6 +13980,17 @@ grokdeclarator (const cp_declarator *declarator,
if (declspecs->gnu_thread_keyword_p)
SET_DECL_GNU_TLS_P (decl);
}
+
+ /* Set the constraints on declaration. */
+ bool memtmpl = (processing_template_decl
+ > template_class_depth (current_class_type));
+ if (memtmpl)
+ {
+ tree tmpl_reqs
+ = TEMPLATE_PARMS_CONSTRAINTS (current_template_parms);
+ tree ci = build_constraints (tmpl_reqs, NULL_TREE);
+ set_constraints (decl, ci);
+ }
}
else
{
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index 224dd9ebd2b..613d87f2637 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -2218,7 +2218,8 @@ determine_specialization (tree template_id,
targs = coerce_template_parms (parms, explicit_targs, fns,
tf_warning_or_error,
/*req_all*/true, /*use_defarg*/true);
- if (targs != error_mark_node)
+ if (targs != error_mark_node
+ && constraints_satisfied_p (fns, targs))
templates = tree_cons (targs, fns, templates);
}
else for (lkp_iterator iter (fns); iter; ++iter)
@@ -14920,6 +14921,11 @@ tsubst_decl (tree t, tree args, tsubst_flags_t
complain)
if (DECL_NAMESPACE_SCOPE_P (t))
DECL_NOT_REALLY_EXTERN (r) = 1;
+ /* Propagate the declaration's constraints. */
+ if (VAR_P (r) && DECL_CLASS_SCOPE_P (r))
+ if (tree ci = get_constraints (t))
+ set_constraints (r, ci);
+
DECL_TEMPLATE_INFO (r) = build_template_info (tmpl, argvec);
SET_DECL_IMPLICIT_INSTANTIATION (r);
if (!error_operand_p (r) || (complain & tf_error))
diff --git a/gcc/testsuite/g++.dg/cpp2a/concepts-var-templ1.C
b/gcc/testsuite/g++.dg/cpp2a/concepts-var-templ1.C
new file mode 100644
index 00000000000..80b48ba3a3d
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp2a/concepts-var-templ1.C
@@ -0,0 +1,9 @@
+// PR c++/98486
+// { dg-do compile { target c++20 } }
+
+template<class T, class U> concept C = __is_same(T, U);
+
+template<C<int>> int v;
+
+template<> int v<int>;
+template<> int v<char>; // { dg-error "match" }
diff --git a/gcc/testsuite/g++.dg/cpp2a/concepts-var-templ1a.C
b/gcc/testsuite/g++.dg/cpp2a/concepts-var-templ1a.C
new file mode 100644
index 00000000000..b12d37d8b7e
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp2a/concepts-var-templ1a.C
@@ -0,0 +1,14 @@
+// PR c++/98486
+// { dg-do compile { target c++20 } }
+
+template<class T, class U> concept C = __is_same(T, U);
+
+struct A {
+ template<C<int>> static int v;
+};
+
+template<> int A::v<int>;
+template<> int A::v<char>; // { dg-error "match" }
+
+int x = A::v<int>;
+int y = A::v<char>; // { dg-error "invalid" }
diff --git a/gcc/testsuite/g++.dg/cpp2a/concepts-var-templ1b.C
b/gcc/testsuite/g++.dg/cpp2a/concepts-var-templ1b.C
new file mode 100644
index 00000000000..37d7f0fc654
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp2a/concepts-var-templ1b.C
@@ -0,0 +1,15 @@
+// PR c++/98486
+// { dg-do compile { target c++20 } }
+
+template<class T, class U> concept C = __is_same(T, U);
+
+template<class T>
+struct A {
+ template<C<T>> static int v;
+};
+
+template<> template<> int A<int>::v<int>;
+template<> template<> int A<int>::v<char>; // { dg-error "match" }
+
+int x = A<int>::v<int>;
+int y = A<int>::v<char>; // { dg-error "invalid" }
