| Vet is a tool that checks correctness of Go programs. It runs a suite of tests, | |
| each tailored to check for a particular class of errors. Examples include incorrect | |
| Printf format verbs and malformed build tags. | |
| Over time many checks have been added to vet's suite, but many more have been | |
| rejected as not appropriate for the tool. The criteria applied when selecting which | |
| checks to add are: | |
| Correctness: | |
| Vet's checks are about correctness, not style. A vet check must identify real or | |
| potential bugs that could cause incorrect compilation or execution. A check that | |
| only identifies stylistic points or alternative correct approaches to a situation | |
| is not acceptable. | |
| Frequency: | |
| Vet is run every day by many programmers, often as part of every compilation or | |
| submission. The cost in execution time is considerable, especially in aggregate, | |
| so checks must be likely enough to find real problems that they are worth the | |
| overhead of the added check. A new check that finds only a handful of problems | |
| across all existing programs, even if the problem is significant, is not worth | |
| adding to the suite everyone runs daily. | |
| Precision: | |
| Most of vet's checks are heuristic and can generate both false positives (flagging | |
| correct programs) and false negatives (not flagging incorrect ones). The rate of | |
| both these failures must be very small. A check that is too noisy will be ignored | |
| by the programmer overwhelmed by the output; a check that misses too many of the | |
| cases it's looking for will give a false sense of security. Neither is acceptable. | |
| A vet check must be accurate enough that everything it reports is worth examining, | |
| and complete enough to encourage real confidence. |