PR c++/19989

cp/pt.c (tsubst): Accept zero-length array if tf_error is set
in complain flags.  Change error message for negative-
length array.
testsuite/g++.dg/ext/array2.C: New test.
testsuite/g++.dg/template/dependent-name3.C: New test.
testsuite/g++.dg/template/dependent-name4.C: New test.
testsuite/g++.dg/template/sfinae2.C: New test.



git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@106468 138bc75d-0d04-0410-961f-82ee72b054a4