/cp
2018-02-15  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/84330
	* constraint.cc (tsubst_constraint_info): Handle an error_mark_node
	as first argument.

/testsuite
2018-02-15  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/84330
	* g++.dg/concepts/pr84330.C: New.

From-SVN: r257698