Tested x86_64-pc-linux-gnu, applying to trunk.
commit c977f3b7668e49eb8f8fd3fdabb6cc7a47e37adc
Author: Jason Merrill <ja...@redhat.com>
Date: Wed Mar 14 23:29:39 2018 -0400
PR c++/84801 - ICE with unexpanded pack in lambda.
* pt.c (check_for_bare_parameter_packs): Don't return early for a
lambda in non-template context.
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index 2ea5fc79a2c..32af3a4822e 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -4043,7 +4043,8 @@ check_for_bare_parameter_packs (tree t)
return false;
/* A lambda might use a parameter pack from the containing context. */
- if (current_class_type && LAMBDA_TYPE_P (current_class_type))
+ if (current_class_type && LAMBDA_TYPE_P (current_class_type)
+ && CLASSTYPE_TEMPLATE_INFO (current_class_type))
return false;
if (TREE_CODE (t) == TYPE_DECL)
diff --git a/gcc/testsuite/g++.dg/cpp1y/lambda-generic-variadic15.C b/gcc/testsuite/g++.dg/cpp1y/lambda-generic-variadic15.C
new file mode 100644
index 00000000000..1de72712643
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1y/lambda-generic-variadic15.C
@@ -0,0 +1,5 @@
+// PR c++/84801
+// { dg-do compile { target c++14 } }
+
+int v;
+int main() { [](auto... c) { v = c; }(1); } // { dg-error "not expanded" }
