gometalinter

command module
Version: v3.0.0 Latest Latest
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Published: Jan 29, 2019 License: MIT Imports: 23 Imported by: 0

README

Go Meta Linter

Build Status Gitter chat

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.

Installing

Binary Releases

To install the latest stable release:

curl -L https://git.io/vp6lP | sh

Alternatively you can install a specific version from the releases list.

Homebrew
brew tap alecthomas/homebrew-tap
brew install gometalinter

Editor integration

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.
  • staticcheck - Statically detect bugs, both obvious and subtle ones.
  • 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.
  • gosec - 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.
  • gochecknoinits - Report init functions, to reduce side effects in code.
  • gochecknoglobals - Report global vars, to reduce side effects 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.
  • safesql - Finds potential SQL injection vulnerabilities.

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 called .gometalinter.json that can be placed at the root of your project. The configuration file will be automatically loaded from the working directory or any parent directory and can be overridden by passing --config=<file> or ignored with --no-config. 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"]
}

If a .gometalinter.json file is loaded, individual options can still be overridden by passing command-line flags. All flags are parsed in order, meaning configuration passed with the --config flag will override any command-line flags passed before and be overridden by flags passed after.

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 arguments
  • Pattern - a regular expression used to parse the linter output
  • IsFast - if the linter should be run when the --fast flag is used
  • PartitionStrategy - how paths args should be passed to the linter command:
    • directories - call the linter once with a list of all the directories
    • files - call the linter once with a list of all the files
    • packages - call the linter once with a list of all the package paths
    • files-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' .

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:

  1. 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 for defer r.Close() will also be suppressed.

    a := 10 // nolint
    a = 2
    defer r.Close() // nolint: errcheck
    
  2. 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).

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:

  1. Linters break, causing gometalinter --install --update to error (this is no longer an issue as all linters are vendored).
  2. gometalinter 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.

Many unexpected errors are being reported

If you see a whole bunch of errors being reported that you wouldn't expect, such as compile errors, this typically means that something is wrong with your Go environment. Try go install and fix any issues with your go installation, then try gometalinter again.

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
curl -L https://git.io/vp6lP | sh

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):

  1. Upstream linter has changed its output or semantics.
  2. gometalinter is not invoking the tool correctly.
  3. gometalinter regular expression matches are not correct for a linter.
  4. 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

The Go Gopher

There is no documentation for this package.

Directories

Path Synopsis
_linters
src/github.com/BurntSushi/toml
Package toml provides facilities for decoding and encoding TOML configuration files via reflection.
Package toml provides facilities for decoding and encoding TOML configuration files via reflection.
src/github.com/BurntSushi/toml/cmd/toml-test-decoder
Command toml-test-decoder satisfies the toml-test interface for testing TOML decoders.
Command toml-test-decoder satisfies the toml-test interface for testing TOML decoders.
src/github.com/BurntSushi/toml/cmd/toml-test-encoder
Command toml-test-encoder satisfies the toml-test interface for testing TOML encoders.
Command toml-test-encoder satisfies the toml-test interface for testing TOML encoders.
src/github.com/BurntSushi/toml/cmd/tomlv
Command tomlv validates TOML documents and prints each key's type.
Command tomlv validates TOML documents and prints each key's type.
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/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/securego/gosec
Package gosec holds the central scanning logic used by gosec security scanner
Package gosec holds the central scanning logic used by gosec security scanner
src/github.com/stretchr/objx
Objx - Go package for dealing with maps, slices, JSON and other data.
Objx - Go package for dealing with maps, slices, JSON and other data.
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/expect
Package expect provides support for interpreting structured comments in Go source code as test expectations.
Package expect provides support for interpreting structured comments in Go source code as test expectations.
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/packages
Package packages loads Go packages for inspection and analysis.
Package packages loads Go packages for inspection and analysis.
src/golang.org/x/tools/go/packages/gopackages
The gopackages command is a diagnostic tool that demonstrates how to use golang.org/x/tools/go/packages to load, parse, type-check, and print one or more Go packages.
The gopackages command is a diagnostic tool that demonstrates how to use golang.org/x/tools/go/packages to load, parse, type-check, and print one or more Go packages.
src/golang.org/x/tools/go/packages/packagestest
Package packagestest creates temporary projects on disk for testing go tools on.
Package packagestest creates temporary projects on disk for testing go tools on.
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/gopkg.in/yaml.v2
Package yaml implements YAML support for the Go language.
Package yaml implements YAML support for the Go language.
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 analyses Go code and makes it better.
staticcheck analyses Go code and makes it better.
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 staticcheck
Package lint provides the foundation for tools like staticcheck
src/honnef.co/go/tools/lint/lintdsl
Package lintdsl provides helpers for implementing static analysis checks.
Package lintdsl provides helpers for implementing static analysis checks.
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/lint/lintutil/format
Package format provides formatters for linter problems.
Package format provides formatters for linter problems.
src/honnef.co/go/tools/lint/testutil
Package testutil provides helpers for testing staticcheck.
Package testutil provides helpers for testing staticcheck.
src/honnef.co/go/tools/printf
Package printf implements a parser for fmt.Printf-style format strings.
Package printf implements a parser for fmt.Printf-style format strings.
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.

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