avoid a warning

diff --git a/tests/performance/valgrind_instrumentation.h b/tests/performance/valgrind_instrumentation.h
index 31132441b90b62ecb7d18b6aeb0cb15cdf032798..b8b9dc22573cb6e38fad0bdcbc5adadd3bf3ad83 100644 (file)
--- a/tests/performance/valgrind_instrumentation.h
+++ b/tests/performance/valgrind_instrumentation.h
@@ -61,7 +61,7 @@ namespace callgrind_wrapper
       std::remove("callgrind.out");
       CALLGRIND_ZERO_STATS;
       CALLGRIND_START_INSTRUMENTATION;
-      const auto my_pid = getpid(); // do something useful
+      const unsigned my_pid = getpid(); // do something useful
       CALLGRIND_DUMP_STATS_AT("callgrind-wrapper-token");
       CALLGRIND_STOP_INSTRUMENTATION;