Standard Library
Defects that arise not from a language’s core semantics but from misuse of the
standard library and platform runtime — the allocator, the printf family,
mutexes, hash maps, the threading layer, and the pseudo-random generator. These
are well-documented interfaces with precise contracts, yet their preconditions
are easy to violate in ways the compiler cannot catch.
The recurring theme is a mismatch between what the caller assumes and what the API actually guarantees: a format string that disagrees with its arguments, a lock released twice or never taken, a generator reseeded on every call, a zero-size allocation whose return value is implementation-defined. Each entry isolates one such contract and the undefined behavior, crash, or silent corruption that follows when it is broken.