For example, the wired tiger shutdown code decides whether or not to leak memory by checking preprocessor variables, but only checks the clang version (__has_feature(address_sanitizer)):

https://github.com/mongodb/mongo/blob/r3.3.3/src/mongo/db/storage/wiredtiger/wiredtiger_kv_engine.cpp#L319-L323

This can lead to confusion when seeing memory leaks when ASan is used with the gcc compiler.

As suggested by max.hirschhorn, both the gcc and clang variables should be checked, as is done in shell_utils.cpp:

https://github.com/mongodb/mongo/blob/r3.3.3/src/mongo/shell/shell_utils.cpp#L154-L169