I saw a failure in this test while testing another patch. I reran the test a number of times and couldn't reproduce it, but fortunately it prints out its random seed. I hacked that value into the initial seed in util/regression/rand/assoc/rand_regression_test.hpp, and now it fails 100% of the time:
detected leaks! 0x59c570: 515, 0 Failure at /space/fsf/commit/gcc/libstdc++-v3/testsuite/util/regression/rand/assoc/detail/operator_fn_imps.hpp: 192 container: Test failed with seed 1153519516 -- Summary: ext/pb_ds/regression/tree_data_map_rand.cc fails with a particular random seed. Product: gcc Version: 4.2.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: libstdc++ AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: drow at gcc dot gnu dot org GCC host triplet: x86_64-pc-linux-gnu http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28457