[libc++] Add missing FILE_DEPENDENCIES markup

diff --git a/libcxx/test/std/input.output/file.streams/fstreams/filebuf.virtuals/pbackfail.pass.cpp b/libcxx/test/std/input.output/file.streams/fstreams/filebuf.virtuals/pbackfail.pass.cpp
index 728eec2..03aff16 100644 (file)
--- a/libcxx/test/std/input.output/file.streams/fstreams/filebuf.virtuals/pbackfail.pass.cpp
+++ b/libcxx/test/std/input.output/file.streams/fstreams/filebuf.virtuals/pbackfail.pass.cpp
@@ -10,6 +10,8 @@
 
 // int_type pbackfail(int_type c = traits::eof());
 
+// FILE_DEPENDENCIES: underflow.dat
+
 #include <fstream>
 #include <cassert>