Don't perform extra go env calls in go/packages.
Load only needed go env vars in golangci-lint.
Stay in sync by enabled analyzers in go vet: remove nilness and
atomicalign analyzers, add errorsas analyzer.
Don't build SSA for govet.
Standalone govet runs 25% faster than before. All runs can be 5-10% faster
than before.
Relates: #208
Use go/packages instead of x/tools/loader: it allows to work
with go modules and speedups loading of packages with the help
of build cache.
A lot of linters became "fast": they are enabled by --fast now and
work in 1-2 seconds. Only unparam, interfacer and megacheck
are "slow" linters now.
Average project is analyzed 20-40% faster than before if all linters are
enabled! If we enable all linters except unparam, interfacer and
megacheck analysis is 10-20x faster!
1. Log all warnings, don't hide none of them
2. Write fatal messages (stop analysis) with error log level
3. Remove ugly timestamp counter from logrus output
4. Print nested module prefix in log
5. Make logger abstraction: no global logging anymore
6. Refactor config reading to config.FileReader struct to avoid passing
logger into every function
7. Replace exit codes hardcoding with constants in exitcodes package
8. Fail test if any warning was logged
9. Fix calculation of relative path if we analyze parent dir ../
10. Move Runner initialization from Executor to NewRunner func
11. Log every AST parsing error
12. Properly print used config file path in verbose mode
13. Print package files if only 1 package is analyzedin verbose mode,
print not compiling packages in verbose mode
14. Forbid usage of github.com/sirupsen/logrus by DepGuard linter
15. Add default ignore pattern to folint: "comment on exported const"
