thread sanitizer ignore for std::basic_string::~basic_string()

tools/valgrind/tsan/ignores.txt

 # This file lists the functions, object files and source files
 # which should be ignored (i.e. not instrumented) by ThreadSanitizer.
 # See http://code.google.com/p/data-race-test/wiki/ThreadSanitizerIgnores.
 
 # ignore these libraries
 obj:*/ld-2*
 obj:*/libpthread-*
 obj:*/libfreetype*
 
 # we ignore the whole NSS library for now since
@@ skipping 23 matching lines @@
 
 # ignore libc's printf functions
 fun_r:_IO_*
 fun:vfprintf
 fun:fwrite
 fun:fflush
 
 # Don't instrument intercepts
 src:*ts_valgrind_intercepts.c
 
+# std::basic_string uses an un-annotated atomic refcount for its COW
+# implementation. Ignore std::basic_string<...>::~basic_string() which is
+# reported as concurrent read of the refcount.
+fun:_ZNSsD1Ev
+
 ##################################################################
 # Don't instrument synchronization code
 src:*base/waitable_event*
 src:*base/atomic*
 src:*base/condition_variable*
 src:*base/lock*
 src:*base/stats_counters*
 src:*base/thread_local_storage*
 
 # Don't instrument tcmalloc
@@ skipping 27 matching lines @@
 # This function generates 25% of memory accesses in net_unittests
 fun:*icu_4_2*UnicodeSet*add*
 
 # There's some weird failure test going on in this tiny test function in sqlite
 fun_r:threadLockingTest
 
 # Ignore accesses below GetCurrentThreadIdentifier.
 # There is a benign race which is hard to suppress properly,
 # see http://crbug.com/44580
 fun_r:*ChromeThread*GetCurrentThreadIdentifier*