The glibc repository has multiple test cases for atexit, it seems a lot of the current behavior derives from a fix for this bug in 2005: https://sourceware.org/

The glibc repository has multiple test cases for atexit, it seems a lot of the current behavior derives from a fix for this bug in 2005: https://sourceware.org/bugzilla/show_bug.cgi?id=1158 https://sourceware.org/bugzilla/show_bug.cgi?id=1158 It seems odd for the author to have invested so much time in this, but not to have found or patches those glibc test case to demonstrate the behavior he expects in various hairy test cases glibc itself is worrying about, and which forms the basis for its current behavior.