re PR c++/67980 (left shift count is negative [-Wshift-count-negative] generated for unreachable code)

/cp
2016-11-04  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/67980
	* pt.c (tsubst_expr, case IF_STMT): Use fold_non_dependent_expr
	to suppress unwanted warnings.

/testsuite
2016-11-04  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/67980
	* g++.dg/cpp1y/pr67980.C: New.

From-SVN: r241858