Adding upstream version 1.21.8.upstream/1.21.8

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

2 files changed, 1140 insertions, 0 deletions

diff --git a/src/cmd/go/internal/help/help.go b/src/cmd/go/internal/help/help.go
new file mode 100644
index 0000000..aeaba78
--- /dev/null
+++ b/src/cmd/go/internal/help/help.go
@@ -0,0 +1,195 @@
+// Copyright 2017 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package help implements the “go help” command.
+package help
+
+import (
+	"bufio"
+	"fmt"
+	"io"
+	"os"
+	"strings"
+	"text/template"
+	"unicode"
+	"unicode/utf8"
+
+	"cmd/go/internal/base"
+	"cmd/go/internal/modload"
+)
+
+// Help implements the 'help' command.
+func Help(w io.Writer, args []string) {
+	// 'go help documentation' generates doc.go.
+	if len(args) == 1 && args[0] == "documentation" {
+		fmt.Fprintln(w, "// Copyright 2011 The Go Authors. All rights reserved.")
+		fmt.Fprintln(w, "// Use of this source code is governed by a BSD-style")
+		fmt.Fprintln(w, "// license that can be found in the LICENSE file.")
+		fmt.Fprintln(w)
+		fmt.Fprintln(w, "// Code generated by 'go test cmd/go -v -run=TestDocsUpToDate -fixdocs'; DO NOT EDIT.")
+		fmt.Fprintln(w, "// Edit the documentation in other files and then execute 'go generate cmd/go' to generate this one.")
+		fmt.Fprintln(w)
+		buf := new(strings.Builder)
+		PrintUsage(buf, base.Go)
+		usage := &base.Command{Long: buf.String()}
+		cmds := []*base.Command{usage}
+		for _, cmd := range base.Go.Commands {
+			// Avoid duplication of the "get" documentation.
+			if cmd.UsageLine == "module-get" && modload.Enabled() {
+				continue
+			} else if cmd.UsageLine == "gopath-get" && !modload.Enabled() {
+				continue
+			}
+			cmds = append(cmds, cmd)
+			cmds = append(cmds, cmd.Commands...)
+		}
+		tmpl(&commentWriter{W: w}, documentationTemplate, cmds)
+		fmt.Fprintln(w, "package main")
+		return
+	}
+
+	cmd := base.Go
+Args:
+	for i, arg := range args {
+		for _, sub := range cmd.Commands {
+			if sub.Name() == arg {
+				cmd = sub
+				continue Args
+			}
+		}
+
+		// helpSuccess is the help command using as many args as possible that would succeed.
+		helpSuccess := "go help"
+		if i > 0 {
+			helpSuccess += " " + strings.Join(args[:i], " ")
+		}
+		fmt.Fprintf(os.Stderr, "go help %s: unknown help topic. Run '%s'.\n", strings.Join(args, " "), helpSuccess)
+		base.SetExitStatus(2) // failed at 'go help cmd'
+		base.Exit()
+	}
+
+	if len(cmd.Commands) > 0 {
+		PrintUsage(os.Stdout, cmd)
+	} else {
+		tmpl(os.Stdout, helpTemplate, cmd)
+	}
+	// not exit 2: succeeded at 'go help cmd'.
+	return
+}
+
+var usageTemplate = `{{.Long | trim}}
+
+Usage:
+
+	{{.UsageLine}} <command> [arguments]
+
+The commands are:
+{{range .Commands}}{{if or (.Runnable) .Commands}}
+	{{.Name | printf "%-11s"}} {{.Short}}{{end}}{{end}}
+
+Use "go help{{with .LongName}} {{.}}{{end}} <command>" for more information about a command.
+{{if eq (.UsageLine) "go"}}
+Additional help topics:
+{{range .Commands}}{{if and (not .Runnable) (not .Commands)}}
+	{{.Name | printf "%-15s"}} {{.Short}}{{end}}{{end}}
+
+Use "go help{{with .LongName}} {{.}}{{end}} <topic>" for more information about that topic.
+{{end}}
+`
+
+var helpTemplate = `{{if .Runnable}}usage: {{.UsageLine}}
+
+{{end}}{{.Long | trim}}
+`
+
+var documentationTemplate = `{{range .}}{{if .Short}}{{.Short | capitalize}}
+
+{{end}}{{if .Commands}}` + usageTemplate + `{{else}}{{if .Runnable}}Usage:
+
+	{{.UsageLine}}
+
+{{end}}{{.Long | trim}}
+
+
+{{end}}{{end}}`
+
+// commentWriter writes a Go comment to the underlying io.Writer,
+// using line comment form (//).
+type commentWriter struct {
+	W            io.Writer
+	wroteSlashes bool // Wrote "//" at the beginning of the current line.
+}
+
+func (c *commentWriter) Write(p []byte) (int, error) {
+	var n int
+	for i, b := range p {
+		if !c.wroteSlashes {
+			s := "//"
+			if b != '\n' {
+				s = "// "
+			}
+			if _, err := io.WriteString(c.W, s); err != nil {
+				return n, err
+			}
+			c.wroteSlashes = true
+		}
+		n0, err := c.W.Write(p[i : i+1])
+		n += n0
+		if err != nil {
+			return n, err
+		}
+		if b == '\n' {
+			c.wroteSlashes = false
+		}
+	}
+	return len(p), nil
+}
+
+// An errWriter wraps a writer, recording whether a write error occurred.
+type errWriter struct {
+	w   io.Writer
+	err error
+}
+
+func (w *errWriter) Write(b []byte) (int, error) {
+	n, err := w.w.Write(b)
+	if err != nil {
+		w.err = err
+	}
+	return n, err
+}
+
+// tmpl executes the given template text on data, writing the result to w.
+func tmpl(w io.Writer, text string, data any) {
+	t := template.New("top")
+	t.Funcs(template.FuncMap{"trim": strings.TrimSpace, "capitalize": capitalize})
+	template.Must(t.Parse(text))
+	ew := &errWriter{w: w}
+	err := t.Execute(ew, data)
+	if ew.err != nil {
+		// I/O error writing. Ignore write on closed pipe.
+		if strings.Contains(ew.err.Error(), "pipe") {
+			base.SetExitStatus(1)
+			base.Exit()
+		}
+		base.Fatalf("writing output: %v", ew.err)
+	}
+	if err != nil {
+		panic(err)
+	}
+}
+
+func capitalize(s string) string {
+	if s == "" {
+		return s
+	}
+	r, n := utf8.DecodeRuneInString(s)
+	return string(unicode.ToTitle(r)) + s[n:]
+}
+
+func PrintUsage(w io.Writer, cmd *base.Command) {
+	bw := bufio.NewWriter(w)
+	tmpl(bw, usageTemplate, cmd)
+	bw.Flush()
+}
diff --git a/src/cmd/go/internal/help/helpdoc.go b/src/cmd/go/internal/help/helpdoc.go
new file mode 100644
index 0000000..68ac4d2
--- /dev/null
+++ b/src/cmd/go/internal/help/helpdoc.go
@@ -0,0 +1,945 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package help
+
+import "cmd/go/internal/base"
+
+var HelpC = &base.Command{
+	UsageLine: "c",
+	Short:     "calling between Go and C",
+	Long: `
+There are two different ways to call between Go and C/C++ code.
+
+The first is the cgo tool, which is part of the Go distribution. For
+information on how to use it see the cgo documentation (go doc cmd/cgo).
+
+The second is the SWIG program, which is a general tool for
+interfacing between languages. For information on SWIG see
+http://swig.org/. When running go build, any file with a .swig
+extension will be passed to SWIG. Any file with a .swigcxx extension
+will be passed to SWIG with the -c++ option.
+
+When either cgo or SWIG is used, go build will pass any .c, .m, .s, .S
+or .sx files to the C compiler, and any .cc, .cpp, .cxx files to the C++
+compiler. The CC or CXX environment variables may be set to determine
+the C or C++ compiler, respectively, to use.
+	`,
+}
+
+var HelpPackages = &base.Command{
+	UsageLine: "packages",
+	Short:     "package lists and patterns",
+	Long: `
+Many commands apply to a set of packages:
+
+	go <action> [packages]
+
+Usually, [packages] is a list of import paths.
+
+An import path that is a rooted path or that begins with
+a . or .. element is interpreted as a file system path and
+denotes the package in that directory.
+
+Otherwise, the import path P denotes the package found in
+the directory DIR/src/P for some DIR listed in the GOPATH
+environment variable (For more details see: 'go help gopath').
+
+If no import paths are given, the action applies to the
+package in the current directory.
+
+There are four reserved names for paths that should not be used
+for packages to be built with the go tool:
+
+- "main" denotes the top-level package in a stand-alone executable.
+
+- "all" expands to all packages found in all the GOPATH
+trees. For example, 'go list all' lists all the packages on the local
+system. When using modules, "all" expands to all packages in
+the main module and their dependencies, including dependencies
+needed by tests of any of those.
+
+- "std" is like all but expands to just the packages in the standard
+Go library.
+
+- "cmd" expands to the Go repository's commands and their
+internal libraries.
+
+Import paths beginning with "cmd/" only match source code in
+the Go repository.
+
+An import path is a pattern if it includes one or more "..." wildcards,
+each of which can match any string, including the empty string and
+strings containing slashes. Such a pattern expands to all package
+directories found in the GOPATH trees with names matching the
+patterns.
+
+To make common patterns more convenient, there are two special cases.
+First, /... at the end of the pattern can match an empty string,
+so that net/... matches both net and packages in its subdirectories, like net/http.
+Second, any slash-separated pattern element containing a wildcard never
+participates in a match of the "vendor" element in the path of a vendored
+package, so that ./... does not match packages in subdirectories of
+./vendor or ./mycode/vendor, but ./vendor/... and ./mycode/vendor/... do.
+Note, however, that a directory named vendor that itself contains code
+is not a vendored package: cmd/vendor would be a command named vendor,
+and the pattern cmd/... matches it.
+See golang.org/s/go15vendor for more about vendoring.
+
+An import path can also name a package to be downloaded from
+a remote repository. Run 'go help importpath' for details.
+
+Every package in a program must have a unique import path.
+By convention, this is arranged by starting each path with a
+unique prefix that belongs to you. For example, paths used
+internally at Google all begin with 'google', and paths
+denoting remote repositories begin with the path to the code,
+such as 'github.com/user/repo'.
+
+Packages in a program need not have unique package names,
+but there are two reserved package names with special meaning.
+The name main indicates a command, not a library.
+Commands are built into binaries and cannot be imported.
+The name documentation indicates documentation for
+a non-Go program in the directory. Files in package documentation
+are ignored by the go command.
+
+As a special case, if the package list is a list of .go files from a
+single directory, the command is applied to a single synthesized
+package made up of exactly those files, ignoring any build constraints
+in those files and ignoring any other files in the directory.
+
+Directory and file names that begin with "." or "_" are ignored
+by the go tool, as are directories named "testdata".
+	`,
+}
+
+var HelpImportPath = &base.Command{
+	UsageLine: "importpath",
+	Short:     "import path syntax",
+	Long: `
+
+An import path (see 'go help packages') denotes a package stored in the local
+file system. In general, an import path denotes either a standard package (such
+as "unicode/utf8") or a package found in one of the work spaces (For more
+details see: 'go help gopath').
+
+Relative import paths
+
+An import path beginning with ./ or ../ is called a relative path.
+The toolchain supports relative import paths as a shortcut in two ways.
+
+First, a relative path can be used as a shorthand on the command line.
+If you are working in the directory containing the code imported as
+"unicode" and want to run the tests for "unicode/utf8", you can type
+"go test ./utf8" instead of needing to specify the full path.
+Similarly, in the reverse situation, "go test .." will test "unicode" from
+the "unicode/utf8" directory. Relative patterns are also allowed, like
+"go test ./..." to test all subdirectories. See 'go help packages' for details
+on the pattern syntax.
+
+Second, if you are compiling a Go program not in a work space,
+you can use a relative path in an import statement in that program
+to refer to nearby code also not in a work space.
+This makes it easy to experiment with small multipackage programs
+outside of the usual work spaces, but such programs cannot be
+installed with "go install" (there is no work space in which to install them),
+so they are rebuilt from scratch each time they are built.
+To avoid ambiguity, Go programs cannot use relative import paths
+within a work space.
+
+Remote import paths
+
+Certain import paths also
+describe how to obtain the source code for the package using
+a revision control system.
+
+A few common code hosting sites have special syntax:
+
+	Bitbucket (Git, Mercurial)
+
+		import "bitbucket.org/user/project"
+		import "bitbucket.org/user/project/sub/directory"
+
+	GitHub (Git)
+
+		import "github.com/user/project"
+		import "github.com/user/project/sub/directory"
+
+	Launchpad (Bazaar)
+
+		import "launchpad.net/project"
+		import "launchpad.net/project/series"
+		import "launchpad.net/project/series/sub/directory"
+
+		import "launchpad.net/~user/project/branch"
+		import "launchpad.net/~user/project/branch/sub/directory"
+
+	IBM DevOps Services (Git)
+
+		import "hub.jazz.net/git/user/project"
+		import "hub.jazz.net/git/user/project/sub/directory"
+
+For code hosted on other servers, import paths may either be qualified
+with the version control type, or the go tool can dynamically fetch
+the import path over https/http and discover where the code resides
+from a <meta> tag in the HTML.
+
+To declare the code location, an import path of the form
+
+	repository.vcs/path
+
+specifies the given repository, with or without the .vcs suffix,
+using the named version control system, and then the path inside
+that repository. The supported version control systems are:
+
+	Bazaar      .bzr
+	Fossil      .fossil
+	Git         .git
+	Mercurial   .hg
+	Subversion  .svn
+
+For example,
+
+	import "example.org/user/foo.hg"
+
+denotes the root directory of the Mercurial repository at
+example.org/user/foo or foo.hg, and
+
+	import "example.org/repo.git/foo/bar"
+
+denotes the foo/bar directory of the Git repository at
+example.org/repo or repo.git.
+
+When a version control system supports multiple protocols,
+each is tried in turn when downloading. For example, a Git
+download tries https://, then git+ssh://.
+
+By default, downloads are restricted to known secure protocols
+(e.g. https, ssh). To override this setting for Git downloads, the
+GIT_ALLOW_PROTOCOL environment variable can be set (For more details see:
+'go help environment').
+
+If the import path is not a known code hosting site and also lacks a
+version control qualifier, the go tool attempts to fetch the import
+over https/http and looks for a <meta> tag in the document's HTML
+<head>.
+
+The meta tag has the form:
+
+	<meta name="go-import" content="import-prefix vcs repo-root">
+
+The import-prefix is the import path corresponding to the repository
+root. It must be a prefix or an exact match of the package being
+fetched with "go get". If it's not an exact match, another http
+request is made at the prefix to verify the <meta> tags match.
+
+The meta tag should appear as early in the file as possible.
+In particular, it should appear before any raw JavaScript or CSS,
+to avoid confusing the go command's restricted parser.
+
+The vcs is one of "bzr", "fossil", "git", "hg", "svn".
+
+The repo-root is the root of the version control system
+containing a scheme and not containing a .vcs qualifier.
+
+For example,
+
+	import "example.org/pkg/foo"
+
+will result in the following requests:
+
+	https://example.org/pkg/foo?go-get=1 (preferred)
+	http://example.org/pkg/foo?go-get=1  (fallback, only with use of correctly set GOINSECURE)
+
+If that page contains the meta tag
+
+	<meta name="go-import" content="example.org git https://code.org/r/p/exproj">
+
+the go tool will verify that https://example.org/?go-get=1 contains the
+same meta tag and then git clone https://code.org/r/p/exproj into
+GOPATH/src/example.org.
+
+When using GOPATH, downloaded packages are written to the first directory
+listed in the GOPATH environment variable.
+(See 'go help gopath-get' and 'go help gopath'.)
+
+When using modules, downloaded packages are stored in the module cache.
+See https://golang.org/ref/mod#module-cache.
+
+When using modules, an additional variant of the go-import meta tag is
+recognized and is preferred over those listing version control systems.
+That variant uses "mod" as the vcs in the content value, as in:
+
+	<meta name="go-import" content="example.org mod https://code.org/moduleproxy">
+
+This tag means to fetch modules with paths beginning with example.org
+from the module proxy available at the URL https://code.org/moduleproxy.
+See https://golang.org/ref/mod#goproxy-protocol for details about the
+proxy protocol.
+
+Import path checking
+
+When the custom import path feature described above redirects to a
+known code hosting site, each of the resulting packages has two possible
+import paths, using the custom domain or the known hosting site.
+
+A package statement is said to have an "import comment" if it is immediately
+followed (before the next newline) by a comment of one of these two forms:
+
+	package math // import "path"
+	package math /* import "path" */
+
+The go command will refuse to install a package with an import comment
+unless it is being referred to by that import path. In this way, import comments
+let package authors make sure the custom import path is used and not a
+direct path to the underlying code hosting site.
+
+Import path checking is disabled for code found within vendor trees.
+This makes it possible to copy code into alternate locations in vendor trees
+without needing to update import comments.
+
+Import path checking is also disabled when using modules.
+Import path comments are obsoleted by the go.mod file's module statement.
+
+See https://golang.org/s/go14customimport for details.
+	`,
+}
+
+var HelpGopath = &base.Command{
+	UsageLine: "gopath",
+	Short:     "GOPATH environment variable",
+	Long: `
+The Go path is used to resolve import statements.
+It is implemented by and documented in the go/build package.
+
+The GOPATH environment variable lists places to look for Go code.
+On Unix, the value is a colon-separated string.
+On Windows, the value is a semicolon-separated string.
+On Plan 9, the value is a list.
+
+If the environment variable is unset, GOPATH defaults
+to a subdirectory named "go" in the user's home directory
+($HOME/go on Unix, %USERPROFILE%\go on Windows),
+unless that directory holds a Go distribution.
+Run "go env GOPATH" to see the current GOPATH.
+
+See https://golang.org/wiki/SettingGOPATH to set a custom GOPATH.
+
+Each directory listed in GOPATH must have a prescribed structure:
+
+The src directory holds source code. The path below src
+determines the import path or executable name.
+
+The pkg directory holds installed package objects.
+As in the Go tree, each target operating system and
+architecture pair has its own subdirectory of pkg
+(pkg/GOOS_GOARCH).
+
+If DIR is a directory listed in the GOPATH, a package with
+source in DIR/src/foo/bar can be imported as "foo/bar" and
+has its compiled form installed to "DIR/pkg/GOOS_GOARCH/foo/bar.a".
+
+The bin directory holds compiled commands.
+Each command is named for its source directory, but only
+the final element, not the entire path. That is, the
+command with source in DIR/src/foo/quux is installed into
+DIR/bin/quux, not DIR/bin/foo/quux. The "foo/" prefix is stripped
+so that you can add DIR/bin to your PATH to get at the
+installed commands. If the GOBIN environment variable is
+set, commands are installed to the directory it names instead
+of DIR/bin. GOBIN must be an absolute path.
+
+Here's an example directory layout:
+
+    GOPATH=/home/user/go
+
+    /home/user/go/
+        src/
+            foo/
+                bar/               (go code in package bar)
+                    x.go
+                quux/              (go code in package main)
+                    y.go
+        bin/
+            quux                   (installed command)
+        pkg/
+            linux_amd64/
+                foo/
+                    bar.a          (installed package object)
+
+Go searches each directory listed in GOPATH to find source code,
+but new packages are always downloaded into the first directory
+in the list.
+
+See https://golang.org/doc/code.html for an example.
+
+GOPATH and Modules
+
+When using modules, GOPATH is no longer used for resolving imports.
+However, it is still used to store downloaded source code (in GOPATH/pkg/mod)
+and compiled commands (in GOPATH/bin).
+
+Internal Directories
+
+Code in or below a directory named "internal" is importable only
+by code in the directory tree rooted at the parent of "internal".
+Here's an extended version of the directory layout above:
+
+    /home/user/go/
+        src/
+            crash/
+                bang/              (go code in package bang)
+                    b.go
+            foo/                   (go code in package foo)
+                f.go
+                bar/               (go code in package bar)
+                    x.go
+                internal/
+                    baz/           (go code in package baz)
+                        z.go
+                quux/              (go code in package main)
+                    y.go
+
+
+The code in z.go is imported as "foo/internal/baz", but that
+import statement can only appear in source files in the subtree
+rooted at foo. The source files foo/f.go, foo/bar/x.go, and
+foo/quux/y.go can all import "foo/internal/baz", but the source file
+crash/bang/b.go cannot.
+
+See https://golang.org/s/go14internal for details.
+
+Vendor Directories
+
+Go 1.6 includes support for using local copies of external dependencies
+to satisfy imports of those dependencies, often referred to as vendoring.
+
+Code below a directory named "vendor" is importable only
+by code in the directory tree rooted at the parent of "vendor",
+and only using an import path that omits the prefix up to and
+including the vendor element.
+
+Here's the example from the previous section,
+but with the "internal" directory renamed to "vendor"
+and a new foo/vendor/crash/bang directory added:
+
+    /home/user/go/
+        src/
+            crash/
+                bang/              (go code in package bang)
+                    b.go
+            foo/                   (go code in package foo)
+                f.go
+                bar/               (go code in package bar)
+                    x.go
+                vendor/
+                    crash/
+                        bang/      (go code in package bang)
+                            b.go
+                    baz/           (go code in package baz)
+                        z.go
+                quux/              (go code in package main)
+                    y.go
+
+The same visibility rules apply as for internal, but the code
+in z.go is imported as "baz", not as "foo/vendor/baz".
+
+Code in vendor directories deeper in the source tree shadows
+code in higher directories. Within the subtree rooted at foo, an import
+of "crash/bang" resolves to "foo/vendor/crash/bang", not the
+top-level "crash/bang".
+
+Code in vendor directories is not subject to import path
+checking (see 'go help importpath').
+
+When 'go get' checks out or updates a git repository, it now also
+updates submodules.
+
+Vendor directories do not affect the placement of new repositories
+being checked out for the first time by 'go get': those are always
+placed in the main GOPATH, never in a vendor subtree.
+
+See https://golang.org/s/go15vendor for details.
+	`,
+}
+
+var HelpEnvironment = &base.Command{
+	UsageLine: "environment",
+	Short:     "environment variables",
+	Long: `
+
+The go command and the tools it invokes consult environment variables
+for configuration. If an environment variable is unset or empty, the go
+command uses a sensible default setting. To see the effective setting of
+the variable <NAME>, run 'go env <NAME>'. To change the default setting,
+run 'go env -w <NAME>=<VALUE>'. Defaults changed using 'go env -w'
+are recorded in a Go environment configuration file stored in the
+per-user configuration directory, as reported by os.UserConfigDir.
+The location of the configuration file can be changed by setting
+the environment variable GOENV, and 'go env GOENV' prints the
+effective location, but 'go env -w' cannot change the default location.
+See 'go help env' for details.
+
+General-purpose environment variables:
+
+	GO111MODULE
+		Controls whether the go command runs in module-aware mode or GOPATH mode.
+		May be "off", "on", or "auto".
+		See https://golang.org/ref/mod#mod-commands.
+	GCCGO
+		The gccgo command to run for 'go build -compiler=gccgo'.
+	GOARCH
+		The architecture, or processor, for which to compile code.
+		Examples are amd64, 386, arm, ppc64.
+	GOBIN
+		The directory where 'go install' will install a command.
+	GOCACHE
+		The directory where the go command will store cached
+		information for reuse in future builds.
+	GOMODCACHE
+		The directory where the go command will store downloaded modules.
+	GODEBUG
+		Enable various debugging facilities. See https://go.dev/doc/godebug
+		for details.
+	GOENV
+		The location of the Go environment configuration file.
+		Cannot be set using 'go env -w'.
+		Setting GOENV=off in the environment disables the use of the
+		default configuration file.
+	GOFLAGS
+		A space-separated list of -flag=value settings to apply
+		to go commands by default, when the given flag is known by
+		the current command. Each entry must be a standalone flag.
+		Because the entries are space-separated, flag values must
+		not contain spaces. Flags listed on the command line
+		are applied after this list and therefore override it.
+	GOINSECURE
+		Comma-separated list of glob patterns (in the syntax of Go's path.Match)
+		of module path prefixes that should always be fetched in an insecure
+		manner. Only applies to dependencies that are being fetched directly.
+		GOINSECURE does not disable checksum database validation. GOPRIVATE or
+		GONOSUMDB may be used to achieve that.
+	GOOS
+		The operating system for which to compile code.
+		Examples are linux, darwin, windows, netbsd.
+	GOPATH
+		Controls where various files are stored. See: 'go help gopath'.
+	GOPROXY
+		URL of Go module proxy. See https://golang.org/ref/mod#environment-variables
+		and https://golang.org/ref/mod#module-proxy for details.
+	GOPRIVATE, GONOPROXY, GONOSUMDB
+		Comma-separated list of glob patterns (in the syntax of Go's path.Match)
+		of module path prefixes that should always be fetched directly
+		or that should not be compared against the checksum database.
+		See https://golang.org/ref/mod#private-modules.
+	GOROOT
+		The root of the go tree.
+	GOSUMDB
+		The name of checksum database to use and optionally its public key and
+		URL. See https://golang.org/ref/mod#authenticating.
+	GOTOOLCHAIN
+		Controls which Go toolchain is used. See https://go.dev/doc/toolchain.
+	GOTMPDIR
+		The directory where the go command will write
+		temporary source files, packages, and binaries.
+	GOVCS
+		Lists version control commands that may be used with matching servers.
+		See 'go help vcs'.
+	GOWORK
+		In module aware mode, use the given go.work file as a workspace file.
+		By default or when GOWORK is "auto", the go command searches for a
+		file named go.work in the current directory and then containing directories
+		until one is found. If a valid go.work file is found, the modules
+		specified will collectively be used as the main modules. If GOWORK
+		is "off", or a go.work file is not found in "auto" mode, workspace
+		mode is disabled.
+
+Environment variables for use with cgo:
+
+	AR
+		The command to use to manipulate library archives when
+		building with the gccgo compiler.
+		The default is 'ar'.
+	CC
+		The command to use to compile C code.
+	CGO_ENABLED
+		Whether the cgo command is supported. Either 0 or 1.
+	CGO_CFLAGS
+		Flags that cgo will pass to the compiler when compiling
+		C code.
+	CGO_CFLAGS_ALLOW
+		A regular expression specifying additional flags to allow
+		to appear in #cgo CFLAGS source code directives.
+		Does not apply to the CGO_CFLAGS environment variable.
+	CGO_CFLAGS_DISALLOW
+		A regular expression specifying flags that must be disallowed
+		from appearing in #cgo CFLAGS source code directives.
+		Does not apply to the CGO_CFLAGS environment variable.
+	CGO_CPPFLAGS, CGO_CPPFLAGS_ALLOW, CGO_CPPFLAGS_DISALLOW
+		Like CGO_CFLAGS, CGO_CFLAGS_ALLOW, and CGO_CFLAGS_DISALLOW,
+		but for the C preprocessor.
+	CGO_CXXFLAGS, CGO_CXXFLAGS_ALLOW, CGO_CXXFLAGS_DISALLOW
+		Like CGO_CFLAGS, CGO_CFLAGS_ALLOW, and CGO_CFLAGS_DISALLOW,
+		but for the C++ compiler.
+	CGO_FFLAGS, CGO_FFLAGS_ALLOW, CGO_FFLAGS_DISALLOW
+		Like CGO_CFLAGS, CGO_CFLAGS_ALLOW, and CGO_CFLAGS_DISALLOW,
+		but for the Fortran compiler.
+	CGO_LDFLAGS, CGO_LDFLAGS_ALLOW, CGO_LDFLAGS_DISALLOW
+		Like CGO_CFLAGS, CGO_CFLAGS_ALLOW, and CGO_CFLAGS_DISALLOW,
+		but for the linker.
+	CXX
+		The command to use to compile C++ code.
+	FC
+		The command to use to compile Fortran code.
+	PKG_CONFIG
+		Path to pkg-config tool.
+
+Architecture-specific environment variables:
+
+	GOARM
+		For GOARCH=arm, the ARM architecture for which to compile.
+		Valid values are 5, 6, 7.
+	GO386
+		For GOARCH=386, how to implement floating point instructions.
+		Valid values are sse2 (default), softfloat.
+	GOAMD64
+		For GOARCH=amd64, the microarchitecture level for which to compile.
+		Valid values are v1 (default), v2, v3, v4.
+		See https://golang.org/wiki/MinimumRequirements#amd64
+	GOMIPS
+		For GOARCH=mips{,le}, whether to use floating point instructions.
+		Valid values are hardfloat (default), softfloat.
+	GOMIPS64
+		For GOARCH=mips64{,le}, whether to use floating point instructions.
+		Valid values are hardfloat (default), softfloat.
+	GOPPC64
+		For GOARCH=ppc64{,le}, the target ISA (Instruction Set Architecture).
+		Valid values are power8 (default), power9, power10.
+	GOWASM
+		For GOARCH=wasm, comma-separated list of experimental WebAssembly features to use.
+		Valid values are satconv, signext.
+
+Environment variables for use with code coverage:
+
+	GOCOVERDIR
+		Directory into which to write code coverage data files
+		generated by running a "go build -cover" binary.
+		Requires that GOEXPERIMENT=coverageredesign is enabled.
+
+Special-purpose environment variables:
+
+	GCCGOTOOLDIR
+		If set, where to find gccgo tools, such as cgo.
+		The default is based on how gccgo was configured.
+	GOEXPERIMENT
+		Comma-separated list of toolchain experiments to enable or disable.
+		The list of available experiments may change arbitrarily over time.
+		See src/internal/goexperiment/flags.go for currently valid values.
+		Warning: This variable is provided for the development and testing
+		of the Go toolchain itself. Use beyond that purpose is unsupported.
+	GOROOT_FINAL
+		The root of the installed Go tree, when it is
+		installed in a location other than where it is built.
+		File names in stack traces are rewritten from GOROOT to
+		GOROOT_FINAL.
+	GO_EXTLINK_ENABLED
+		Whether the linker should use external linking mode
+		when using -linkmode=auto with code that uses cgo.
+		Set to 0 to disable external linking mode, 1 to enable it.
+	GIT_ALLOW_PROTOCOL
+		Defined by Git. A colon-separated list of schemes that are allowed
+		to be used with git fetch/clone. If set, any scheme not explicitly
+		mentioned will be considered insecure by 'go get'.
+		Because the variable is defined by Git, the default value cannot
+		be set using 'go env -w'.
+
+Additional information available from 'go env' but not read from the environment:
+
+	GOEXE
+		The executable file name suffix (".exe" on Windows, "" on other systems).
+	GOGCCFLAGS
+		A space-separated list of arguments supplied to the CC command.
+	GOHOSTARCH
+		The architecture (GOARCH) of the Go toolchain binaries.
+	GOHOSTOS
+		The operating system (GOOS) of the Go toolchain binaries.
+	GOMOD
+		The absolute path to the go.mod of the main module.
+		If module-aware mode is enabled, but there is no go.mod, GOMOD will be
+		os.DevNull ("/dev/null" on Unix-like systems, "NUL" on Windows).
+		If module-aware mode is disabled, GOMOD will be the empty string.
+	GOTOOLDIR
+		The directory where the go tools (compile, cover, doc, etc...) are installed.
+	GOVERSION
+		The version of the installed Go tree, as reported by runtime.Version.
+	`,
+}
+
+var HelpFileType = &base.Command{
+	UsageLine: "filetype",
+	Short:     "file types",
+	Long: `
+The go command examines the contents of a restricted set of files
+in each directory. It identifies which files to examine based on
+the extension of the file name. These extensions are:
+
+	.go
+		Go source files.
+	.c, .h
+		C source files.
+		If the package uses cgo or SWIG, these will be compiled with the
+		OS-native compiler (typically gcc); otherwise they will
+		trigger an error.
+	.cc, .cpp, .cxx, .hh, .hpp, .hxx
+		C++ source files. Only useful with cgo or SWIG, and always
+		compiled with the OS-native compiler.
+	.m
+		Objective-C source files. Only useful with cgo, and always
+		compiled with the OS-native compiler.
+	.s, .S, .sx
+		Assembler source files.
+		If the package uses cgo or SWIG, these will be assembled with the
+		OS-native assembler (typically gcc (sic)); otherwise they
+		will be assembled with the Go assembler.
+	.swig, .swigcxx
+		SWIG definition files.
+	.syso
+		System object files.
+
+Files of each of these types except .syso may contain build
+constraints, but the go command stops scanning for build constraints
+at the first item in the file that is not a blank line or //-style
+line comment. See the go/build package documentation for
+more details.
+	`,
+}
+
+var HelpBuildmode = &base.Command{
+	UsageLine: "buildmode",
+	Short:     "build modes",
+	Long: `
+The 'go build' and 'go install' commands take a -buildmode argument which
+indicates which kind of object file is to be built. Currently supported values
+are:
+
+	-buildmode=archive
+		Build the listed non-main packages into .a files. Packages named
+		main are ignored.
+
+	-buildmode=c-archive
+		Build the listed main package, plus all packages it imports,
+		into a C archive file. The only callable symbols will be those
+		functions exported using a cgo //export comment. Requires
+		exactly one main package to be listed.
+
+	-buildmode=c-shared
+		Build the listed main package, plus all packages it imports,
+		into a C shared library. The only callable symbols will
+		be those functions exported using a cgo //export comment.
+		Requires exactly one main package to be listed.
+
+	-buildmode=default
+		Listed main packages are built into executables and listed
+		non-main packages are built into .a files (the default
+		behavior).
+
+	-buildmode=shared
+		Combine all the listed non-main packages into a single shared
+		library that will be used when building with the -linkshared
+		option. Packages named main are ignored.
+
+	-buildmode=exe
+		Build the listed main packages and everything they import into
+		executables. Packages not named main are ignored.
+
+	-buildmode=pie
+		Build the listed main packages and everything they import into
+		position independent executables (PIE). Packages not named
+		main are ignored.
+
+	-buildmode=plugin
+		Build the listed main packages, plus all packages that they
+		import, into a Go plugin. Packages not named main are ignored.
+
+On AIX, when linking a C program that uses a Go archive built with
+-buildmode=c-archive, you must pass -Wl,-bnoobjreorder to the C compiler.
+`,
+}
+
+var HelpCache = &base.Command{
+	UsageLine: "cache",
+	Short:     "build and test caching",
+	Long: `
+The go command caches build outputs for reuse in future builds.
+The default location for cache data is a subdirectory named go-build
+in the standard user cache directory for the current operating system.
+Setting the GOCACHE environment variable overrides this default,
+and running 'go env GOCACHE' prints the current cache directory.
+
+The go command periodically deletes cached data that has not been
+used recently. Running 'go clean -cache' deletes all cached data.
+
+The build cache correctly accounts for changes to Go source files,
+compilers, compiler options, and so on: cleaning the cache explicitly
+should not be necessary in typical use. However, the build cache
+does not detect changes to C libraries imported with cgo.
+If you have made changes to the C libraries on your system, you
+will need to clean the cache explicitly or else use the -a build flag
+(see 'go help build') to force rebuilding of packages that
+depend on the updated C libraries.
+
+The go command also caches successful package test results.
+See 'go help test' for details. Running 'go clean -testcache' removes
+all cached test results (but not cached build results).
+
+The go command also caches values used in fuzzing with 'go test -fuzz',
+specifically, values that expanded code coverage when passed to a
+fuzz function. These values are not used for regular building and
+testing, but they're stored in a subdirectory of the build cache.
+Running 'go clean -fuzzcache' removes all cached fuzzing values.
+This may make fuzzing less effective, temporarily.
+
+The GODEBUG environment variable can enable printing of debugging
+information about the state of the cache:
+
+GODEBUG=gocacheverify=1 causes the go command to bypass the
+use of any cache entries and instead rebuild everything and check
+that the results match existing cache entries.
+
+GODEBUG=gocachehash=1 causes the go command to print the inputs
+for all of the content hashes it uses to construct cache lookup keys.
+The output is voluminous but can be useful for debugging the cache.
+
+GODEBUG=gocachetest=1 causes the go command to print details of its
+decisions about whether to reuse a cached test result.
+`,
+}
+
+var HelpBuildConstraint = &base.Command{
+	UsageLine: "buildconstraint",
+	Short:     "build constraints",
+	Long: `
+A build constraint, also known as a build tag, is a condition under which a
+file should be included in the package. Build constraints are given by a
+line comment that begins
+
+	//go:build
+
+Constraints may appear in any kind of source file (not just Go), but
+they must appear near the top of the file, preceded
+only by blank lines and other line comments. These rules mean that in Go
+files a build constraint must appear before the package clause.
+
+To distinguish build constraints from package documentation,
+a build constraint should be followed by a blank line.
+
+A build constraint comment is evaluated as an expression containing
+build tags combined by ||, &&, and ! operators and parentheses.
+Operators have the same meaning as in Go.
+
+For example, the following build constraint constrains a file to
+build when the "linux" and "386" constraints are satisfied, or when
+"darwin" is satisfied and "cgo" is not:
+
+	//go:build (linux && 386) || (darwin && !cgo)
+
+It is an error for a file to have more than one //go:build line.
+
+During a particular build, the following build tags are satisfied:
+
+	- the target operating system, as spelled by runtime.GOOS, set with the
+	  GOOS environment variable.
+	- the target architecture, as spelled by runtime.GOARCH, set with the
+	  GOARCH environment variable.
+	- any architecture features, in the form GOARCH.feature
+	  (for example, "amd64.v2"), as detailed below.
+	- "unix", if GOOS is a Unix or Unix-like system.
+	- the compiler being used, either "gc" or "gccgo"
+	- "cgo", if the cgo command is supported (see CGO_ENABLED in
+	  'go help environment').
+	- a term for each Go major release, through the current version:
+	  "go1.1" from Go version 1.1 onward, "go1.12" from Go 1.12, and so on.
+	- any additional tags given by the -tags flag (see 'go help build').
+
+There are no separate build tags for beta or minor releases.
+
+If a file's name, after stripping the extension and a possible _test suffix,
+matches any of the following patterns:
+	*_GOOS
+	*_GOARCH
+	*_GOOS_GOARCH
+(example: source_windows_amd64.go) where GOOS and GOARCH represent
+any known operating system and architecture values respectively, then
+the file is considered to have an implicit build constraint requiring
+those terms (in addition to any explicit constraints in the file).
+
+Using GOOS=android matches build tags and files as for GOOS=linux
+in addition to android tags and files.
+
+Using GOOS=illumos matches build tags and files as for GOOS=solaris
+in addition to illumos tags and files.
+
+Using GOOS=ios matches build tags and files as for GOOS=darwin
+in addition to ios tags and files.
+
+The defined architecture feature build tags are:
+
+	- For GOARCH=386, GO386=387 and GO386=sse2
+	  set the 386.387 and 386.sse2 build tags, respectively.
+	- For GOARCH=amd64, GOAMD64=v1, v2, and v3
+	  correspond to the amd64.v1, amd64.v2, and amd64.v3 feature build tags.
+	- For GOARCH=arm, GOARM=5, 6, and 7
+	  correspond to the arm.5, arm.6, and arm.7 feature build tags.
+	- For GOARCH=mips or mipsle,
+	  GOMIPS=hardfloat and softfloat
+	  correspond to the mips.hardfloat and mips.softfloat
+	  (or mipsle.hardfloat and mipsle.softfloat) feature build tags.
+	- For GOARCH=mips64 or mips64le,
+	  GOMIPS64=hardfloat and softfloat
+	  correspond to the mips64.hardfloat and mips64.softfloat
+	  (or mips64le.hardfloat and mips64le.softfloat) feature build tags.
+	- For GOARCH=ppc64 or ppc64le,
+	  GOPPC64=power8, power9, and power10 correspond to the
+	  ppc64.power8, ppc64.power9, and ppc64.power10
+	  (or ppc64le.power8, ppc64le.power9, and ppc64le.power10)
+	  feature build tags.
+	- For GOARCH=wasm, GOWASM=satconv and signext
+	  correspond to the wasm.satconv and wasm.signext feature build tags.
+
+For GOARCH=amd64, arm, ppc64, and ppc64le, a particular feature level
+sets the feature build tags for all previous levels as well.
+For example, GOAMD64=v2 sets the amd64.v1 and amd64.v2 feature flags.
+This ensures that code making use of v2 features continues to compile
+when, say, GOAMD64=v4 is introduced.
+Code handling the absence of a particular feature level
+should use a negation:
+
+	//go:build !amd64.v2
+
+To keep a file from being considered for any build:
+
+	//go:build ignore
+
+(Any other unsatisfied word will work as well, but "ignore" is conventional.)
+
+To build a file only when using cgo, and only on Linux and OS X:
+
+	//go:build cgo && (linux || darwin)
+
+Such a file is usually paired with another file implementing the
+default functionality for other systems, which in this case would
+carry the constraint:
+
+	//go:build !(cgo && (linux || darwin))
+
+Naming a file dns_windows.go will cause it to be included only when
+building the package for Windows; similarly, math_386.s will be included
+only when building the package for 32-bit x86.
+
+Go versions 1.16 and earlier used a different syntax for build constraints,
+with a "// +build" prefix. The gofmt command will add an equivalent //go:build
+constraint when encountering the older syntax.
+`,
+}