The number of tools for statically checking Go source for errors and warnings is impressive.
This is a tool that concurrently runs a whole bunch of those linters and normalises their output to a standard format:
<file>:<line>:[<column>]: <message> (<linter>)
eg.
stutter.go:9::warning: unused global variable unusedGlobal (varcheck)
stutter.go:12:6:warning: exported type MyStruct should have comment or be unexported (golint)
It is intended for use with editor/IDE integration.
- go vet - Reports potential errors that otherwise compile.
- go vet --shadow - Reports variables that may have been unintentionally shadowed.
- gotype - Syntactic and semantic analysis similar to the Go compiler.
- deadcode - Finds unused code.
- gocyclo - Computes the cyclomatic complexity of functions.
- golint - Google's (mostly stylistic) linter.
- defercheck - Checks for duplicate defer calls.
- varcheck - Find unused global variables and constants.
- structcheck - Find unused struct fields.
- errcheck - Check that error return values are used.
- dupl - Reports potentially duplicated code.
Disabled by default (enable with --enable=<linter>):
- testify - Show location of failed testify assertions (disabled by default).
- test - Show location of test failures from the stdlib testing module (disabled by default).
Additional linters can be added through the command line with --linter=NAME:COMMAND:PATTERN (see below).
Install gometalinter:
$ go get github.com/alecthomas/gometalinter
Install all known linters:
$ gometalinter --install --update
Installing golint -> go get -u github.com/golang/lint/golint
Installing gotype -> go get -u golang.org/x/tools/cmd/gotype
Installing defercheck -> go get -u github.com/opennota/check/cmd/defercheck
Installing deadcode -> go get -u github.com/remyoudompheng/go-misc/deadcode
Installing gocyclo -> go get -u github.com/alecthomas/gocyclo
Installing ineffassign -> go get -u github.com/gordonklaus/ineffassign
Installing errcheck -> go get -u github.com/alecthomas/errcheck
Installing varcheck -> go get -u github.com/opennota/check/cmd/varcheck
Installing structcheck -> go get -u github.com/opennota/check/cmd/structcheck
Installing dupl -> go get -u github.com/mibk/dupl
Run it:
$ cd $GOPATH/src/github.com/alecthomas/gometalinter/example
$ gometalinter ./...
stutter.go:13::warning: unused struct field MyStruct.Unused (structcheck)
stutter.go:9::warning: unused global variable unusedGlobal (varcheck)
stutter.go:12:6:warning: exported type MyStruct should have comment or be unexported (golint)
stutter.go:16:6:warning: exported type PublicUndocumented should have comment or be unexported (golint)
stutter.go:22::error: Repeating defer a.Close() inside function duplicateDefer (defercheck)
stutter.go:8:1:warning: unusedGlobal is unused (deadcode)
stutter.go:12:1:warning: MyStruct is unused (deadcode)
stutter.go:16:1:warning: PublicUndocumented is unused (deadcode)
stutter.go:20:1:warning: duplicateDefer is unused (deadcode)
stutter.go:21:15:warning: error return value not checked (defer a.Close()) (errcheck)
stutter.go:22:15:warning: error return value not checked (defer a.Close()) (errcheck)
stutter.go:27:6:warning: error return value not checked (doit() // test for errcheck) (errcheck)
stutter.go:29::error: unreachable code (vet)
stutter.go:26::error: missing argument for Printf("%d"): format reads arg 1, have only 0 args (vet)
Gometalinter also supports the commonly seen <path>/... recursive path
format. Note that this can be very slow.
I forked gocyclo because the upstream behaviour is to recursively check all
subdirectories even when just a single directory is specified. This made it
unusably slow when vendoring. The recursive behaviour can be achieved with
gometalinter by explicitly specifying <path>/.... There is a
pull request open.
errcheck was forked from an old version that was fast.
Upstream subsequently switched to go/loader and became slow
enough to not be usable in an interactive environment. There doesn't seem to be any
functional difference, and in lieu of any interest from upstream in fixing the issue,
the fork remains.
That's more of a statement than a question, but okay.
Sometimes gometalinter will not report issues that you think it should. There are three things to try in that case:
go get -u github.com/alecthomas/gometalinter
gometalinter --install --update
If you're lucky, this will fix the problem.
If that doesn't help, the problem may be elsewhere (in no particular order):
- Upstream linter has changed its output or semantics.
- gometalinter is not invoking the tool correctly.
- gometalinter regular expression matches are not correct for a linter.
- Linter is exceeding the deadline.
To find out what's going on run in debug mode:
gometalinter --debug
This will show all output from the linters and should indicate why it is failing.
Failing all else, if the problem looks like a bug please file an issue and
include the output of gometalinter --debug.
$ gometalinter --help
usage: gometalinter [<flags>] [<path>]
Aggregate and normalise the output of a whole bunch of Go linters.
Default linters:
gotype (golang.org/x/tools/cmd/gotype)
gotype {tests=-a} {path}
:PATH:LINE:COL:MESSAGE
varcheck (github.com/opennota/check/cmd/varcheck)
varcheck {path}
:^(?:[^:]+: )?(?P<path>[^:]+):(?P<line>\d+):(?P<col>\d+):\s*(?P<message>\w+)$
deadcode (github.com/remyoudompheng/go-misc/deadcode)
deadcode {path}
:deadcode: (?P<path>[^:]+):(?P<line>\d+):(?P<col>\d+):\s*(?P<message>.*)
golint (github.com/golang/lint/golint)
golint {path}
:PATH:LINE:COL:MESSAGE
errcheck (github.com/alecthomas/errcheck)
errcheck {path}
:^(?P<path>[^:]+):(?P<line>\d+):(?P<col>\d+)\t(?P<message>.*)$
structcheck (github.com/opennota/check/cmd/structcheck)
structcheck {tests=-t} {path}
:^(?:[^:]+: )?(?P<path>[^:]+):(?P<line>\d+):\s*(?P<message>[\w.]+)$
defercheck (github.com/opennota/check/cmd/defercheck)
defercheck {path}
:PATH:LINE:MESSAGE
gocyclo (github.com/alecthomas/gocyclo)
gocyclo -over {mincyclo} {path}
:^(?P<cyclo>\d+)\s+\S+\s(?P<function>\S+)\s+(?P<path>[^:]+):(?P<line>\d+):(?P<col>\d+)
vet ()
go vet {path}
:PATH:LINE:MESSAGE
vet --shadow ()
go vet --shadow {path}
:PATH:LINE:MESSAGE
Severity override map (default is "error"):
golint -> warning
varcheck -> warning
structcheck -> warning
deadcode -> warning
gocyclo -> warning
errcheck -> warning
Flags:
--help Show help.
--fast Only run fast linters.
-i, --install Attempt to install all known linters.
-u, --update Pass -u to go tool when installing.
-D, --disable=LINTER
List of linters to disable.
-d, --debug Display messages for failed linters, etc.
-j, --concurrency=16
Number of concurrent linters to run.
--exclude=REGEXP Exclude messages matching this regular expression.
--cyclo-over=10 Report functions with cyclomatic complexity over N (using
gocyclo).
--sort=none Sort output by any of none, path, line, column, severity,
message.
-t, --tests Include test files for linters that support this option
--deadline=5s Cancel linters if they have not completed within this
duration.
--errors Only show errors.
--linter=NAME:COMMAND:PATTERN
Specify a linter.
--message-overrides=LINTER:MESSAGE
Override message from linter. {message} will be expanded to
the original message.
--severity=LINTER:SEVERITY
Map of linter severities.
Args:
[<path>] Directory to lint.
Additional linters can be configured via the command line:
$ gometalinter --linter='vet:go tool vet -printfuncs=Infof,Debugf,Warningf,Errorf {paths}:PATH:LINE:MESSAGE' .
stutter.go:22::error: Repeating defer a.Close() inside function duplicateDefer (defercheck)
stutter.go:21:15:warning: error return value not checked (defer a.Close()) (errcheck)
stutter.go:22:15:warning: error return value not checked (defer a.Close()) (errcheck)
stutter.go:27:6:warning: error return value not checked (doit() // test for errcheck) (errcheck)
stutter.go:9::warning: unused global variable unusedGlobal (varcheck)
stutter.go:13::warning: unused struct field MyStruct.Unused (structcheck)
stutter.go:12:6:warning: exported type MyStruct should have comment or be unexported (golint)
stutter.go:16:6:warning: exported type PublicUndocumented should have comment or be unexported (deadcode)