errcheck

README

errcheck

========

errcheck is a program for checking for unchecked errors in go programs.

Install

go get github.com/kisielk/errcheck

errcheck requires Go 1.1 and depends on the go/types package from the go.tools repository.

Use

For basic usage, just give the package path of interest as the first argument:

errcheck github.com/kisielk/errcheck/example

There are currently three flags: -ignore, -ignorepkg and -blank

The -ignore flag takes a comma-separated list of pairs of the form package:regex. For each package, the regex describes which functions to ignore within that package. The package may be omitted to have the regex apply to all packages.

For example, you may wish to ignore common operations like Read and Write:

errcheck -ignore '[rR]ead|[wW]rite' path/to/package

or you may wish to ignore common functions like the print variants in fmt:

errcheck -ignore 'fmt:[FS]?[Pp]rint*' path/to/package

The -ignorepkg flag takes a comma-separated list of package import paths to ignore:

errcheck -ignorepkg 'fmt,encoding/binary' path/to/package

Note that this is equivalent to:

errcheck -ignore 'fmt:.*,encoding/binary:.*' path/to/package

If a regex is provided for a package pkg via -ignore, and pkg also appears in the list of packages passed to -ignorepkg, the latter takes precedence; that is, all functions within pkg will be ignored.

Note that by default the fmt package is ignored entirely, unless a regex is specified for it. To disable this, specify a regex that matches nothing:

errcheck -ignore 'fmt:a^' path/to/package

The -blank flag enables checking for assignments of errors to the blank identifier. It takes no arguments.

An example of using errcheck to check the go standard library packages:

errcheck -ignore 'Close|[wW]rite.*|Flush|Seek|[rR]ead.*' std > stdlibcheck

Or check all packages in your $GOPATH and $GOROOT:

errcheck all > allcheck

To check all packages beneath the current directory:

errcheck ./...

Cgo

Currently errcheck is unable to check packages that import "C" due to limitations in the importer.

However, you can use errcheck on packages that depend on those which use cgo. In order for this to work you need to go install the cgo dependencies before running errcheck on the dependant packages.

See https://github.com/kisielk/errcheck/issues/16 for more details.

Exit Codes

errcheck returns 1 if any problems were found in the checked files. It returns 2 if there were any other failures.

Editor Integration

Emacs

go-errcheck.el integrates errcheck with Emacs by providing a go-errcheck command and customizable variables to automatically pass flags to errcheck.

Vim

go-errcheck-vim integrates errcheck with Vim's quickfix.