Staticcheck 2021.1 release notes

UI improvements

The new -list-checks flag lists all available checks, showing each check’s identifier and one-line description. You can use the existing -explain flag to find out more about each individual check.

Targeted Go version

Some checks in Staticcheck adjust their behavior based on the targeted Go version. For example, the suggestion to use for range instead of for _ = range does not apply to Go 1.3 and earlier.

In the past, the default Go version that was targeted was the version that Staticcheck had been compiled with. For most users, this meant that it targeted the latest Go release. Going forward, we will default to 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 still a better apprximation than “whatever Go version Staticcheck has been compiled with”, and should work fine for most users.

As before, the targeted Go version can be explicitly set by using the -go flag.


New checks

The following new checks have been added:

  • S1040 flags type assertions from an interface type to itself
  • SA1030 flags invalid arguments to various functions in the strconv package
  • SA4005 flags assignments to fields on value receivers that intended the receiver to be a pointer instead
  • SA4024 flags pointless comparisons of the values of len and cap with zero
  • SA4025 flags suspicious integer division that results in zero, such as 2 / 3
  • SA4026 flags constant expressions that try to express negative zero
  • SA4027 flags no-op attempts at modifying a (*net/url.URL)’s query string
  • ST1023 flags variable declarations of the form var x T = v where the type T is redundant; this check is disabled by default

Changed checks

The following checks have been improved:

  • S1025 now recommends converting byte slices to strings instead of using fmt.Sprintf
  • S1008 includes fewer unnecessary parentheses and double negations in its suggested fixes
  • S1017 is now able to flag calls that use string literals and integer literals
  • SA9005 now includes the value’s type in its output
  • ST1000, ST1020, ST1021, and ST1022 no longer flag effectively empty comments, including those that consist entirely of directives

Restructured documentation

The documentation on the website has been restructured and hopefully made more approachable. Instead of being one long document, it is now split into multiple smaller articles. In the future, more articles that look at specific aspects of Staticcheck will be added.

Better integration with gopls

Several behind the scenes changes prepare this release for better integration with gopls. This will include more accurate severities for diagnostics as well as numerous new refactorings. These improvements will be part of a future gopls release.

Deletion of rdeps

The rdeps tool has been deleted. This was a GOPATH-centric tool that allowed finding all reverse dependencies of a Go package. Both the move to Go modules as well as the emergence of much better tooling for inspecting dependencies (such as goda) has made rdeps redundant.

Staticcheck 2021.1.1 release notes

This release adds support for new language features in Go 1.17, namely conversions from slices to array pointers, the unsafe.Add function, and the unsafe.Slice function.

Additionally, it fixes the following false positives:

  • ST1000 no longer flags package docs that start with whitespace if they’re otherwise well-formed.
  • SA5002 no longer prints one too many percent signs in its message.
  • SA4000 no longer flags comparisons between floats.
  • SA4010 no longer flags appends to slices that might share their backing array with other slices.
  • SA5011 no longer infers possible nil pointer dereferences from comparisons done outside of control flow constructs. This avoids false positives when using assert-style functions. See issue 1022 for a concrete example.
  • S1020 no longer flags nested if statements when the inner statement has an else branch.
  • SA5011 no longer claims that indexing a nil slice will cause a nil pointer dereference.

Staticcheck 2021.1.2 release notes

This release fixes the following false positives:

  • SA4000 no longer flags operations involving the math/rand package. This is to allow patterns such as rand.Intn(2) - rand.Intn(2).
  • S1019 no longer recommends replacing make(map[X]Y, 0) with make(map[X]Y) – the latter may allocate a small starting size.
  • SA1026 now more accurately implements the behavior of encoding/json and encoding/xml, which will lead to fewer false positives involving method sets or embedding. It might also find bugs that it previously missed.
  • Checks that are sensitive to control flow, such as SA5011, now recognize functions from and that affect control flow (Panic and Fatal related functions.)

Furthermore, it fixes the following crashes:

  • Using //lint:ignore U1000 on a type alias would crash.
  • Converting a slice to an array pointer, where the array type is a named type, would crash.