This is DR 2032 which says that the restrictions regarding template
parameter packs and default arguments apply to variable templates as
well, but we weren't detecting that.
Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
gcc/cp/ChangeLog:
DR 2032
PR c++/96218
* pt.c (check_default_tmpl_args): Also consider variable
templates.
gcc/testsuite/ChangeLog:
DR 2032
PR c++/96218
* g++.dg/cpp1y/var-templ67.C: New test.
---
gcc/cp/pt.c | 5 +++--
gcc/testsuite/g++.dg/cpp1y/var-templ67.C | 16 ++++++++++++++++
2 files changed, 19 insertions(+), 2 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/cpp1y/var-templ67.C
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index 4e1c77a6bd7..b74074a092b 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -5481,14 +5481,15 @@ check_default_tmpl_args (tree decl, tree parms, bool
is_primary,
/* Don't complain about an enclosing partial
specialization. */
&& parm_level == parms
- && TREE_CODE (decl) == TYPE_DECL
+ && (TREE_CODE (decl) == TYPE_DECL || VAR_P (decl))
&& i < ntparms - 1
&& template_parameter_pack_p (TREE_VALUE (parm))
/* A fixed parameter pack will be partially
instantiated into a fixed length list. */
&& !fixed_parameter_pack_p (TREE_VALUE (parm)))
{
- /* A primary class template can only have one
+ /* A primary class template, primary variable template
+ (DR 2032), or alias template can only have one
parameter pack, at the end of the template
parameter list. */
diff --git a/gcc/testsuite/g++.dg/cpp1y/var-templ67.C
b/gcc/testsuite/g++.dg/cpp1y/var-templ67.C
new file mode 100644
index 00000000000..f36af39bc19
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1y/var-templ67.C
@@ -0,0 +1,16 @@
+// DR 2032 - Default template-arguments of variable templates
+// PR c++/96218
+// { dg-do compile { target c++14 } }
+
+// [temp.param]/14: If a template-parameter of a class template, variable
+// template, or alias template has a default template-argument, each subsequent
+// template-parameter shall either have a default template-argument supplied or
+// be a template parameter pack.
+template<typename T = int, typename U>
+T vt; // { dg-error "no default argument" }
+
+// [temp.param]/14: If a template-parameter of a primary class template,
+// primary variable template, or alias template is a template parameter pack,
+// it shall be the last template-parameter.
+template<typename... Ts, typename U> // { dg-error "must be at the end" }
+int vt2;
base-commit: 866c5bfd9c3ebc00913f3a84eb5383b51f2aee16
--
2.26.2
