README ¶
Go Meta Linter
- Editor integration
- Supported linters
- Configuration file
- Installing
- Comment directives
- Quickstart
- FAQ
- Checkstyle XML format
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.
Editor integration
- SublimeLinter plugin.
- Atom go-plus package.
- Emacs Flycheck checker.
- Go for Visual Studio Code.
- Vim/Neovim
Supported linters
- go vet - Reports potential errors that otherwise compile.
- go tool vet --shadow - Reports variables that may have been unintentionally shadowed.
- gotype - Syntactic and semantic analysis similar to the Go compiler.
- gotype -x - Syntactic and semantic analysis in external test packages (similar to the Go compiler).
- deadcode - Finds unused code.
- gocyclo - Computes the cyclomatic complexity of functions.
- golint - Google's (mostly stylistic) linter.
- varcheck - Find unused global variables and constants.
- structcheck - Find unused struct fields.
- maligned - Detect structs that would take less memory if their fields were sorted.
- errcheck - Check that error return values are used.
- megacheck - Run staticcheck, gosimple and unused, sharing work.
- dupl - Reports potentially duplicated code.
- ineffassign - Detect when assignments to existing variables are not used.
- interfacer - Suggest narrower interfaces that can be used.
- unconvert - Detect redundant type conversions.
- goconst - Finds repeated strings that could be replaced by a constant.
- gas - Inspects source code for security problems by scanning the Go AST.
Disabled by default (enable with --enable=<linter>
):
- testify - Show location of failed testify assertions.
- test - Show location of test failures from the stdlib testing module.
- gofmt -s - Checks if the code is properly formatted and could not be further simplified.
- goimports - Checks missing or unreferenced package imports.
- gosimple - Report simplifications in code.
- lll - Report long lines (see
--line-length=N
). - misspell - Finds commonly misspelled English words.
- nakedret - Finds naked returns.
- unparam - Find unused function parameters.
- unused - Find unused variables.
- safesql - Finds potential SQL injection vulnerabilities.
- staticcheck - Statically detect bugs, both obvious and subtle ones.
Additional linters can be added through the command line with --linter=NAME:COMMAND:PATTERN
(see below).
Configuration file
gometalinter now supports a JSON configuration file which can be loaded via
--config=<file>
. The format of this file is determined by the Config
struct
in config.go.
The configuration file mostly corresponds to command-line flags, with the following exceptions:
- Linters defined in the configuration file will overlay existing definitions, not replace them.
- "Enable" defines the exact set of linters that will be enabled (default
linters are disabled).
--help
displays the list of default linters with the exact names you must use.
Here is an example configuration file:
{
"Enable": ["deadcode", "unconvert"]
}
Format
key
The default Format
key places the different fields of an Issue
into a template. this
corresponds to the --format
option command-line flag.
Default Format
:
Format: "{{.Path}}:{{.Line}}:{{if .Col}}{{.Col}}{{end}}:{{.Severity}}: {{.Message}} ({{.Linter}})"
Format Methods
{{.Path.Relative}}
- equivalent to{{.Path}}
which outputs a relative path to the file{{.Path.Abs}}
- outputs an absolute path to the file
Adding Custom linters
Linters can be added and customized from the config file using the Linters
field.
Linters supports the following fields:
Command
- the path to the linter binary and any default argumentsPattern
- a regular expression used to parse the linter outputIsFast
- if the linter should be run when the--fast
flag is usedPartitionStrategy
- how paths args should be passed to the linter command:directories
- call the linter once with a list of all the directoriesfiles
- call the linter once with a list of all the filespackages
- call the linter once with a list of all the package pathsfiles-by-package
- call the linter once per package with a list of the files in the package.single-directory
- call the linter once per directory
The config for default linters can be overridden by using the name of the linter.
Additional linters can be configured via the command line using the format
NAME:COMMAND:PATTERN
.
Example:
$ gometalinter --linter='vet:go tool vet -printfuncs=Infof,Debugf,Warningf,Errorf:PATH:LINE:MESSAGE' .
Installing
There are two options for installing gometalinter.
- Install a stable version, eg.
go get -u gopkg.in/alecthomas/gometalinter.v1
. I will generally only tag a new stable version when it has passed the Travis regression tests. The downside is that the binary will be calledgometalinter.v1
. - Install from HEAD with:
go get -u github.com/alecthomas/gometalinter
. This has the downside that changes to gometalinter may break.
Comment directives
gometalinter supports suppression of linter messages via comment directives. The form of the directive is:
// nolint[: <linter>[, <linter>, ...]]
Suppression works in the following way:
-
Line-level suppression
A comment directive suppresses any linter messages on that line.
eg. In this example any messages for
a := 10
will be suppressed and errcheck messages fordefer r.Close()
will also be suppressed.a := 10 // nolint a = 2 defer r.Close() // nolint: errcheck
-
Statement-level suppression
A comment directive at the same indentation level as a statement it immediately precedes will also suppress any linter messages in that entire statement.
eg. In this example all messages for
SomeFunc()
will be suppressed.// nolint func SomeFunc() { }
Implementation details: gometalinter now performs parsing of Go source code, to extract linter directives and associate them with line ranges. To avoid unnecessary processing, parsing is on-demand: the first time a linter emits a message for a file, that file is parsed for directives.
Quickstart
Install gometalinter (see above).
Install all known linters:
$ gometalinter --install
Installing:
structcheck
maligned
nakedret
deadcode
gocyclo
ineffassign
dupl
golint
gotype
goimports
errcheck
varcheck
interfacer
goconst
gosimple
staticcheck
unparam
unused
misspell
lll
gas
safesql
Run it:
$ cd 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: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, and you may need to increase the linter --deadline
to allow linters to complete.
FAQ
Exit status
gometalinter sets two bits of the exit status to indicate different issues:
Bit | Meaning |
---|---|
0 | A linter generated an issue. |
1 | An underlying error occurred; eg. a linter failed to execute. In this situation a warning will also be displayed. |
eg. linter only = 1, underlying only = 2, linter + underlying = 3
What's the best way to use gometalinter
in CI?
There are two main problems running in a CI:
Linters break, causing(this is no longer an issue as all linters are vendored).gometalinter --install --update
to errorgometalinter
adds a new linter.
I have solved 1 by vendoring the linters.
For 2, the best option is to disable all linters, then explicitly enable the ones you want:
gometalinter --disable-all --enable=errcheck --enable=vet --enable=vetshadow ...
How do I make gometalinter
work with Go 1.5 vendoring?
gometalinter
has a --vendor
flag that just sets GO15VENDOREXPERIMENT=1
, however the
underlying tools must support it. Ensure that all of the linters are up to date and built with Go 1.5
(gometalinter --install --force
) then run gometalinter --vendor .
. That should be it.
Why does gometalinter --install
install a fork of gocyclo?
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.
Gometalinter is not working
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:
1. Update to the latest build of gometalinter and all linters
go get -u github.com/alecthomas/gometalinter
gometalinter --install
If you're lucky, this will fix the problem.
2. Analyse the debug output
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.
3. Report an issue.
Failing all else, if the problem looks like a bug please file an issue and
include the output of gometalinter --debug
.
How do I filter issues between two git refs?
revgrep can be used to filter the output of gometalinter
to show issues on lines that have changed between two git refs, such as unstaged changes, changes in
HEAD
vs master
and between master
and origin/master
. See the project's documentation and -help
usage for more information.
go get -u github.com/bradleyfalzon/revgrep/...
gometalinter |& revgrep # If unstaged changes or untracked files, those issues are shown.
gometalinter |& revgrep # Else show issues in the last commit.
gometalinter |& revgrep master # Show issues between master and HEAD (or any other reference).
gometalinter |& revgrep origin/master # Show issues that haven't been pushed.
Checkstyle XML format
gometalinter
supports checkstyle
compatible XML output format. It is triggered with --checkstyle
flag:
gometalinter --checkstyle
Checkstyle format can be used to integrate gometalinter with Jenkins CI with the help of Checkstyle Plugin.
Documentation ¶
There is no documentation for this package.
Source Files ¶
Directories ¶
Path | Synopsis |
---|---|
_linters
|
|
src/github.com/GoASTScanner/gas/core
Package core holds the central scanning logic used by GAS (c) Copyright 2016 Hewlett Packard Enterprise Development LP Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License.
|
Package core holds the central scanning logic used by GAS (c) Copyright 2016 Hewlett Packard Enterprise Development LP Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. |
src/github.com/alecthomas/gocyclo
Gocyclo calculates the cyclomatic complexities of functions and methods in Go source code.
|
Gocyclo calculates the cyclomatic complexities of functions and methods in Go source code. |
src/github.com/dnephin/govet
Vet examines Go source code and reports suspicious constructs, such as Printf calls whose arguments do not align with the format string.
|
Vet examines Go source code and reports suspicious constructs, such as Printf calls whose arguments do not align with the format string. |
src/github.com/golang/lint
Package lint contains a linter for Go source code.
|
Package lint contains a linter for Go source code. |
src/github.com/golang/lint/golint
golint lints the Go source files named on its command line.
|
golint lints the Go source files named on its command line. |
src/github.com/jgautheron/goconst
Package goconst finds repeated strings that could be replaced by a constant.
|
Package goconst finds repeated strings that could be replaced by a constant. |
src/github.com/kisielk/gotool
Package gotool contains utility functions used to implement the standard "cmd/go" tool, provided as a convenience to developers who want to write tools with similar semantics.
|
Package gotool contains utility functions used to implement the standard "cmd/go" tool, provided as a convenience to developers who want to write tools with similar semantics. |
src/github.com/mdempsky/unconvert
Unconvert removes redundant type conversions from Go packages.
|
Unconvert removes redundant type conversions from Go packages. |
src/github.com/stripe/safesql
Command safesql is a tool for performing static analysis on programs to ensure that SQL injection attacks are not possible.
|
Command safesql is a tool for performing static analysis on programs to ensure that SQL injection attacks are not possible. |
src/github.com/walle/lll
Package lll provides validation functions regarding line length
|
Package lll provides validation functions regarding line length |
src/golang.org/x/text/transform
Package transform provides reader and writer wrappers that transform the bytes passing through as well as various transformations.
|
Package transform provides reader and writer wrappers that transform the bytes passing through as well as various transformations. |
src/golang.org/x/text/unicode/cldr
Package cldr provides a parser for LDML and related XML formats.
|
Package cldr provides a parser for LDML and related XML formats. |
src/golang.org/x/text/width
Package width provides functionality for handling different widths in text.
|
Package width provides functionality for handling different widths in text. |
src/golang.org/x/tools/cmd/goimports
Command goimports updates your Go import lines, adding missing ones and removing unreferenced ones.
|
Command goimports updates your Go import lines, adding missing ones and removing unreferenced ones. |
src/golang.org/x/tools/cmd/gotype
The gotype command, like the front-end of a Go compiler, parses and type-checks a single Go package.
|
The gotype command, like the front-end of a Go compiler, parses and type-checks a single Go package. |
src/golang.org/x/tools/container/intsets
Package intsets provides Sparse, a compact and fast representation for sparse sets of int values.
|
Package intsets provides Sparse, a compact and fast representation for sparse sets of int values. |
src/golang.org/x/tools/go/ast/astutil
Package astutil contains common utilities for working with the Go AST.
|
Package astutil contains common utilities for working with the Go AST. |
src/golang.org/x/tools/go/buildutil
Package buildutil provides utilities related to the go/build package in the standard library.
|
Package buildutil provides utilities related to the go/build package in the standard library. |
src/golang.org/x/tools/go/callgraph
Package callgraph defines the call graph and various algorithms and utilities to operate on it.
|
Package callgraph defines the call graph and various algorithms and utilities to operate on it. |
src/golang.org/x/tools/go/callgraph/cha
Package cha computes the call graph of a Go program using the Class Hierarchy Analysis (CHA) algorithm.
|
Package cha computes the call graph of a Go program using the Class Hierarchy Analysis (CHA) algorithm. |
src/golang.org/x/tools/go/callgraph/rta
This package provides Rapid Type Analysis (RTA) for Go, a fast algorithm for call graph construction and discovery of reachable code (and hence dead code) and runtime types.
|
This package provides Rapid Type Analysis (RTA) for Go, a fast algorithm for call graph construction and discovery of reachable code (and hence dead code) and runtime types. |
src/golang.org/x/tools/go/callgraph/static
Package static computes the call graph of a Go program containing only static call edges.
|
Package static computes the call graph of a Go program containing only static call edges. |
src/golang.org/x/tools/go/gcexportdata
Package gcexportdata provides functions for locating, reading, and writing export data files containing type information produced by the gc compiler.
|
Package gcexportdata provides functions for locating, reading, and writing export data files containing type information produced by the gc compiler. |
src/golang.org/x/tools/go/gcimporter15
Package gcimporter15 provides various functions for reading gc-generated object files that can be used to implement the Importer interface defined by the Go 1.5 standard library package.
|
Package gcimporter15 provides various functions for reading gc-generated object files that can be used to implement the Importer interface defined by the Go 1.5 standard library package. |
src/golang.org/x/tools/go/loader
Package loader loads a complete Go program from source code, parsing and type-checking the initial packages plus their transitive closure of dependencies.
|
Package loader loads a complete Go program from source code, parsing and type-checking the initial packages plus their transitive closure of dependencies. |
src/golang.org/x/tools/go/pointer
Package pointer implements Andersen's analysis, an inclusion-based pointer analysis algorithm first described in (Andersen, 1994).
|
Package pointer implements Andersen's analysis, an inclusion-based pointer analysis algorithm first described in (Andersen, 1994). |
src/golang.org/x/tools/go/ssa
Package ssa defines a representation of the elements of Go programs (packages, types, functions, variables and constants) using a static single-assignment (SSA) form intermediate representation (IR) for the bodies of functions.
|
Package ssa defines a representation of the elements of Go programs (packages, types, functions, variables and constants) using a static single-assignment (SSA) form intermediate representation (IR) for the bodies of functions. |
src/golang.org/x/tools/go/ssa/interp
Package ssa/interp defines an interpreter for the SSA representation of Go programs.
|
Package ssa/interp defines an interpreter for the SSA representation of Go programs. |
src/golang.org/x/tools/go/types/typeutil
Package typeutil defines various utilities for types, such as Map, a mapping from types.Type to interface{} values.
|
Package typeutil defines various utilities for types, such as Map, a mapping from types.Type to interface{} values. |
src/golang.org/x/tools/imports
Package imports implements a Go pretty-printer (like package "go/format") that also adds or removes import statements as necessary.
|
Package imports implements a Go pretty-printer (like package "go/format") that also adds or removes import statements as necessary. |
src/golang.org/x/tools/refactor/importgraph
Package importgraph computes the forward and reverse import dependency graphs for all packages in a Go workspace.
|
Package importgraph computes the forward and reverse import dependency graphs for all packages in a Go workspace. |
src/honnef.co/go/tools/callgraph
Package callgraph defines the call graph and various algorithms and utilities to operate on it.
|
Package callgraph defines the call graph and various algorithms and utilities to operate on it. |
src/honnef.co/go/tools/callgraph/cha
Package cha computes the call graph of a Go program using the Class Hierarchy Analysis (CHA) algorithm.
|
Package cha computes the call graph of a Go program using the Class Hierarchy Analysis (CHA) algorithm. |
src/honnef.co/go/tools/callgraph/rta
This package provides Rapid Type Analysis (RTA) for Go, a fast algorithm for call graph construction and discovery of reachable code (and hence dead code) and runtime types.
|
This package provides Rapid Type Analysis (RTA) for Go, a fast algorithm for call graph construction and discovery of reachable code (and hence dead code) and runtime types. |
src/honnef.co/go/tools/callgraph/static
Package static computes the call graph of a Go program containing only static call edges.
|
Package static computes the call graph of a Go program containing only static call edges. |
src/honnef.co/go/tools/cmd/gosimple
gosimple detects code that could be rewritten in a simpler way.
|
gosimple detects code that could be rewritten in a simpler way. |
src/honnef.co/go/tools/cmd/keyify
keyify transforms unkeyed struct literals into a keyed ones.
|
keyify transforms unkeyed struct literals into a keyed ones. |
src/honnef.co/go/tools/cmd/megacheck
megacheck runs staticcheck, gosimple and unused.
|
megacheck runs staticcheck, gosimple and unused. |
src/honnef.co/go/tools/cmd/rdeps
rdeps scans GOPATH for all reverse dependencies of a set of Go packages.
|
rdeps scans GOPATH for all reverse dependencies of a set of Go packages. |
src/honnef.co/go/tools/cmd/staticcheck
staticcheck detects a myriad of bugs and inefficiencies in your code.
|
staticcheck detects a myriad of bugs and inefficiencies in your code. |
src/honnef.co/go/tools/cmd/structlayout
structlayout displays the layout (field sizes and padding) of structs.
|
structlayout displays the layout (field sizes and padding) of structs. |
src/honnef.co/go/tools/cmd/structlayout-optimize
structlayout-optimize reorders struct fields to minimize the amount of padding.
|
structlayout-optimize reorders struct fields to minimize the amount of padding. |
src/honnef.co/go/tools/cmd/structlayout-pretty
structlayout-pretty formats the output of structlayout with ASCII art.
|
structlayout-pretty formats the output of structlayout with ASCII art. |
src/honnef.co/go/tools/cmd/unused
unused reports unused identifiers (types, functions, ...) in your code.
|
unused reports unused identifiers (types, functions, ...) in your code. |
src/honnef.co/go/tools/gcsizes
Package gcsizes provides a types.Sizes implementation that adheres to the rules used by the gc compiler.
|
Package gcsizes provides a types.Sizes implementation that adheres to the rules used by the gc compiler. |
src/honnef.co/go/tools/lint
Package lint provides the foundation for tools like gosimple.
|
Package lint provides the foundation for tools like gosimple. |
src/honnef.co/go/tools/lint/lintutil
Package lintutil provides helpers for writing linter command lines.
|
Package lintutil provides helpers for writing linter command lines. |
src/honnef.co/go/tools/simple
Package simple contains a linter for Go source code.
|
Package simple contains a linter for Go source code. |
src/honnef.co/go/tools/ssa
Package ssa defines a representation of the elements of Go programs (packages, types, functions, variables and constants) using a static single-assignment (SSA) form intermediate representation (IR) for the bodies of functions.
|
Package ssa defines a representation of the elements of Go programs (packages, types, functions, variables and constants) using a static single-assignment (SSA) form intermediate representation (IR) for the bodies of functions. |
src/honnef.co/go/tools/staticcheck
Package staticcheck contains a linter for Go source code.
|
Package staticcheck contains a linter for Go source code. |
src/mvdan.cc/lint
Package lint defines common interfaces for Go code checkers.
|
Package lint defines common interfaces for Go code checkers. |
src/mvdan.cc/unparam/check
Package check implements the unparam linter.
|
Package check implements the unparam linter. |