Staticcheck is a tool for statically checking the inputs to and uses of certain functions and constructs, such as regexp.Compile.

Staticcheck requires Go 1.6 or later.

go get honnef.co/go/staticcheck/cmd/staticcheck

Invoke staticcheck with one or more filenames, a directory, or a package named by its import path. Staticcheck uses the same import path syntax as the go command and therefore also supports relative import paths like ./.... Additionally the ... wildcard can be used as suffix on relative and absolute file paths to recurse into them.

The output of this tool is a list of suggestions in Vim quickfix format, which is accepted by lots of different editors.

Staticcheck checks the input to functions like regexp.Compile and time.Parse and makes sure that they conform to the API contract. It does so by finding function calls with constant inputs and then evaluating these inputs in the same way the code would at runtime.

For example, for regexp.Compile("foo("), staticcheck will find the call to regexp.Compile and check if foo( is a valid regexp.

Furthermore, it checks that functions and constructs are used in the correct way. It checks, for example, that sync.WaitGroup.Add is called outside of a goroutine, to avoid race conditions.

The main purpose of staticcheck is editor integration, or workflow integration in general. For example, by running staticcheck when saving a file, one can quickly catch simple bugs without having to run the whole test suite or the program itself.

The tool shouldn't report any errors unless there are legitimate bugs - or very dubious constructs - in the code.

It is similar in nature to go vet, but has more checks that catch bugs that would also be caught easily at runtime, to reduce the number of edit, compile and debug cycles.

The following things are currently checked by staticcheck:

• regexp.Compile and regexp.MustCompile - Checks that the regexp is valid
• time.Parse - Checks that the time format is valid
• encoding/binary.Write - Checks that the written value is supported by encoding/binary
• text/template.Template.Parse and html/template.Template.Parse – Check that the template is syntactically valid
• net/url.Parse - Checks that the URL is valid
• time.Sleep - Checks that the call doesn't use suspiciously small (<120), untyped literals. This usually indicates a bug, where time.Sleep(1) is assumed to sleep for 1 second, while in reality it sleeps for 1 nanosecond.
• sync.WaitGroup.Add – Checks that the method is called before launching the goroutine, to avoid a race condition.
• sync.WaitGroup - Checks that wait groups aren't copied when being passed to functions.
• TestMain - checks that the TestMain function calls os.Exit to report test failure. -- This check may have false positive. Its confidence is 0.9 and can be filtered with the -min_confidence flag set to 1.
• exec.Command - checks that the first argument looks valid
• Dont use an empty for {} as it will spin.
• Don't have an empty default branch in a select in a loop as it will spin.
• Don't use defer in a loop that will never finish.
• Checks that two operands of a binary expression aren't identical. This is a common mistake when copy & pasting code. Example: if x[0] == 1 || x[0] == 1 checks the same index of x twice and probably meant to check two different indices. When the operand contains a function call, the confidence will be 0.9, otherwise it will be 1.
• Checks that break statements aren't missing labels when trying to break out of a loop from inside a switch or select statement.
• Don't use printf-style functions to print dynamic strings with no formatting directives. For example, fmt.Printf(fn()) will produce unexpected results if fn returns "%s".
• Don't defer rc.Close() before having checked the error returned by Open or similar.

github.com/couchbase/indexing/secondary/tools/logd/main.go:134:33: error parsing regexp: missing closing ): ` FEED\[<=>([^\(]*)(`
github.com/jvehent/mig/client/mig-console/action_launcher.go:312:35: parsing time "2014-01-01T00:00:00.0-": month out of range
github.com/khlieng/dispatch/vendor/github.com/xenolf/lego/acme/crypto.go:165:42: type int cannot be used with binary.Write
github.com/netrack/openflow/ofp.v13/error.go:246:43: type *ofp.ErrorMsg cannot be used with binary.Write
github.com/sangelone/wigglr/benchmark_test.go:44:42: type *main.Wiggle cannot be used with binary.Write