Command-line interface

The staticcheck command is the primary way of running Staticcheck.

At its core, the staticcheck command works a lot like go vet or go build. It accepts the same package patterns (see go help packages for details), it outputs problems in the same format, it supports a -tags flag for specifying which build tags to use, and so on. Overall, it is meant to feel like another go command.

However, it also comes with several of its own flags to support some of its unique functionality. This article will focus on explaining that unique functionality.

Explaining checks

You can use staticcheck -explain <check> to get a helpful description of a check.

Every diagnostic that staticcheck reports is annotated with the identifier of the specific check that found the issue. For example, in

foo.go:1248:4: unnecessary use of fmt.Sprintf (S1039)

the check’s identifier is S1039. Running staticcheck -explain S1039 will output the following:

Unnecessary use of fmt.Sprint

Calling fmt.Sprint with a single string argument is unnecessary and identical to using the string directly.

Available since
	2020.1

Online documentation
	https://staticcheck.io/docs/checks#S1039

The output includes a one-line summary, one or more paragraphs of helpful text, the first version of Staticcheck that the check appeared in, and a link to online documentation, which contains the same information as the output of staticcheck -explain.

Selecting an output format

Staticcheck can format its output in a number of ways, by using the -f flag. See this list of formatters for a list of all formatters.

Targeting Go versions

Some of Staticcheck’s analyses adjust their behavior based on the targeted Go version. For example, the suggestion that one use for range xs instead of for _ = range xs only applies to Go 1.4 and later, as it won’t compile with versions of Go older than that.

By default, Staticcheck targets the Go version declared in go.mod via the go directive. Even though this value does not exactly correspond to the module’s minimum supported Go version, it is a good estimate.

You can manually overwrite the targeted Go version by using the -go command line flag. For example, staticcheck -go 1.0 ./... will only make suggestions that work with Go 1.0.

The targeted Go version limits both language features and parts of the standard library that will be recommended.

Excluding tests

By default, Staticcheck analyses packages as well as their tests. By passing -tests=false, one can skip the analysis of tests. This is primarily useful for the U1000 check, as it allows finding code that is only used by tests and would otherwise be unused.