[throwawayish]

If there are multiple releases/branches then I also recommend to very carefully review merges between branches, even files/regions where git (or whatever SCM is used) merged automatically with no conflicts. I've personally seen multiple incidents now were through review bugs and security issues where found in merges that ranged from subtle to catastrophic. I even saw one catastrophic security issue introduced into a file git merged with no conflicts.

(However, more issues are typically introduced by manual conflict resolution, since we humans are also easily confused when doing it. Both are a problem relatively independent of language, although some specific instances might be caught by a compiler or tests. If the latter don't catch it, it may be a sign that some tests are missing.)

Be careful.