Here the template arguments for the partial specialization are valid
arguments for the template, but not for a partial specialization, because
'd' can never be deduced to anything other than an empty pack.
Tested x86_64-pc-linux-gnu, applying to 8/9/10.
gcc/cp/ChangeLog
2020-03-14 Jason Merrill <ja...@redhat.com>
PR c++/92068
* pt.c (process_partial_specialization): Error rather than crash on
extra pack expansion.
---
gcc/cp/pt.c | 9 ++++++++-
gcc/testsuite/g++.dg/cpp0x/variadic178.C | 6 ++++++
2 files changed, 14 insertions(+), 1 deletion(-)
create mode 100644 gcc/testsuite/g++.dg/cpp0x/variadic178.C
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index bd2f9be82ea..48ac48615a0 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -5038,6 +5038,14 @@ process_partial_specialization (tree decl)
return decl;
}
+ else if (nargs > DECL_NTPARMS (maintmpl))
+ {
+ error ("too many arguments for partial specialization %qT", type);
+ inform (DECL_SOURCE_LOCATION (maintmpl), "primary template here");
+ /* Avoid crash below. */
+ return decl;
+ }
+
/* If we aren't in a dependent class, we can actually try deduction. */
else if (tpd.level == 1
/* FIXME we should be able to handle a partial specialization of a
@@ -5064,7 +5072,6 @@ process_partial_specialization (tree decl)
Also, we verify that pack expansions only occur at the
end of the argument list. */
- gcc_assert (nargs == DECL_NTPARMS (maintmpl));
tpd2.parms = 0;
for (i = 0; i < nargs; ++i)
{
diff --git a/gcc/testsuite/g++.dg/cpp0x/variadic178.C
b/gcc/testsuite/g++.dg/cpp0x/variadic178.C
new file mode 100644
index 00000000000..f0e65958de3
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/variadic178.C
@@ -0,0 +1,6 @@
+// PR c++/92068
+// { dg-do compile { target c++11 } }
+
+template <typename, typename> struct a;
+template <typename b, typename c, typename... d>
+struct a<b, c, d...> { }; // { dg-error "arguments" }
base-commit: 53b28abf8e4ba37e47d3bb05476e0a80ae761567
--
2.18.1
