README.md - external/github.com/kisielk/errcheck - Git at Google

 # errcheck

 errcheck is a tool for finding unchecked errors in go programs.

 ## Install

     go get -u github.com/kisielk/errcheck

 errcheck requires Go 1.12 or newer, and depends on the package go/packages from the golang.org/x/tools repository.

 ## Use

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

     errcheck github.com/kisielk/errcheck/testdata

 To check all packages beneath the current directory:

     errcheck ./...

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

     errcheck all

 errcheck also recognizes the following command-line options:

 The `-tags` flag takes a space-separated list of build tags, just like `go
 build`. If you are using any custom build tags in your code base, you may need
 to specify the relevant tags here.

 The `-asserts` flag enables checking for ignored type assertion results. It
 takes no arguments.

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


 ## Excluding functions

 Use the `-exclude` flag to specify a path to a file containing a list of functions to
 be excluded.

     errcheck -exclude errcheck_excludes.txt path/to/package

 The file should contain one function signature per line. The format for function signatures is
 `package.FunctionName` while for methods it's `(package.Receiver).MethodName` for value receivers
 and `(*package.Receiver).MethodName` for pointer receivers. If the function name is followed by string of form `(TYPE)`, then
 the the function call is excluded only if the type of the first argument is `TYPE`. It also accepts a special suffix
 `(os.Stdout)` and `(os.Stderr)`, which excludes the function only when the first argument is a literal `os.Stdout` or `os.Stderr`.

 An example of an exclude file is:

     io/ioutil.ReadFile
     io.Copy(*bytes.Buffer)
     io.Copy(os.Stdout)

     // Sometimes we don't care if a HTTP request fails.
     (*net/http.Client).Do

 By default, the exclude list is combined with an internal list for functions in
 the Go standard library that have an error return type but are documented to never
 return an error. To disable the built-in exclude list, pass the `-excludeonly` flag.

 Run errcheck in `-verbose` mode to see the resulting list of added excludes.

 When using vendored dependencies, specify the full import path. For example:
 * Your project's import path is `example.com/yourpkg`
 * You've vendored `example.net/fmt2` as `vendor/example.net/fmt2`
 * You want to exclude `fmt2.Println` from error checking

 In this case, add this line to your exclude file:
 ```
 example.com/yourpkg/vendor/example.net/fmt2.Println
 ```

 Empty lines and lines starting with `//` are ignored.

 ### The deprecated method

 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 `-ignoretests` flag disables checking of `_test.go` files. It takes
 no arguments.

 ## 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](https://github.com/dominikh/go-errcheck.el)
 integrates errcheck with Emacs by providing a `go-errcheck` command
 and customizable variables to automatically pass flags to errcheck.

 ## Vim

 [vim-go](https://github.com/fatih/vim-go) can run errcheck via both its `:GoErrCheck`
 and `:GoMetaLinter` commands.
	# errcheck

	errcheck is a tool for finding unchecked errors in go programs.

	## Install

	go get -u github.com/kisielk/errcheck

	errcheck requires Go 1.12 or newer, and depends on the package go/packages from the golang.org/x/tools repository.

	## Use

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

	errcheck github.com/kisielk/errcheck/testdata

	To check all packages beneath the current directory:

	errcheck ./...

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

	errcheck all

	errcheck also recognizes the following command-line options:

	The `-tags` flag takes a space-separated list of build tags, just like `go
	build`. If you are using any custom build tags in your code base, you may need
	to specify the relevant tags here.

	The `-asserts` flag enables checking for ignored type assertion results. It
	takes no arguments.

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


	## Excluding functions

	Use the `-exclude` flag to specify a path to a file containing a list of functions to
	be excluded.

	errcheck -exclude errcheck_excludes.txt path/to/package

	The file should contain one function signature per line. The format for function signatures is
	`package.FunctionName` while for methods it's `(package.Receiver).MethodName` for value receivers
	and `(*package.Receiver).MethodName` for pointer receivers. If the function name is followed by string of form `(TYPE)`, then
	the the function call is excluded only if the type of the first argument is `TYPE`. It also accepts a special suffix
	`(os.Stdout)` and `(os.Stderr)`, which excludes the function only when the first argument is a literal `os.Stdout` or `os.Stderr`.

	An example of an exclude file is:

	io/ioutil.ReadFile
	io.Copy(*bytes.Buffer)
	io.Copy(os.Stdout)

	// Sometimes we don't care if a HTTP request fails.
	(*net/http.Client).Do

	By default, the exclude list is combined with an internal list for functions in
	the Go standard library that have an error return type but are documented to never
	return an error. To disable the built-in exclude list, pass the `-excludeonly` flag.

	Run errcheck in `-verbose` mode to see the resulting list of added excludes.

	When using vendored dependencies, specify the full import path. For example:
	* Your project's import path is `example.com/yourpkg`
	* You've vendored `example.net/fmt2` as `vendor/example.net/fmt2`
	* You want to exclude `fmt2.Println` from error checking

	In this case, add this line to your exclude file:
	```
	example.com/yourpkg/vendor/example.net/fmt2.Println
	```

	Empty lines and lines starting with `//` are ignored.

	### The deprecated method

	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 `-ignoretests` flag disables checking of `_test.go` files. It takes
	no arguments.

	## 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](https://github.com/dominikh/go-errcheck.el)
	integrates errcheck with Emacs by providing a `go-errcheck` command
	and customizable variables to automatically pass flags to errcheck.

	## Vim

	[vim-go](https://github.com/fatih/vim-go) can run errcheck via both its `:GoErrCheck`
	and `:GoMetaLinter` commands.