Developers team of the PVS-Studio static code analyzer for C/C++/C#/Java checked the Perl 5 source code and found some errors.
For example, the incorrect using of the ternary operator:
V502 Perhaps the '?:' operator works in a different way than it was expected. The '?:' operator has a lower priority than the '-' operator. toke.c 9494
if (s <= PL_bufend - (is_utf8) ? UTF8SKIP(s) : 1)
All examples are available in the article: Perl 5: How to Hide Errors in Macros.