THE PRODUCTION BUG THAT MADE ME CARE ABOUT UNDEFINED BEHAVIOR

Summary from the TLDR Dev newsletter

A production bug in a C++ payment processing system returned an impossible "error: true, succeeded: true" response, which the author traced to uninitialized boolean fields in a `Response` struct. This seemingly straightforward issue was a consequence of C++'s counter-intuitive default initialization rules for non-POD types, where the compiler-generated default constructor left primitive fields uninitialized. The fix involved either explicitly value-initializing the struct at the call site or providing default member initializers within the struct definition.