re PR c++/78344 (ICE on invalid c++ code on x86_64-linux-gnu (internal compiler error: tree check: expected tree_list, have error_mark in cp_check_const_attributes, at cp/decl2.c:1347))

/cp
2018-01-17  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/78344
	* decl.c (grokdeclarator): Do not append the error_mark_node
	due to an erroneous optional attribute-specifier-seq.

/testsuite
2018-01-17  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/78344
	* g++.dg/cpp0x/alignas13.C: New.

From-SVN: r256821