if ch == nil {
		ch = make(chan struct{})
		installed[dir] = ch
		go runInstall(dir, ch)
	}
	installedMu.Unlock()
	return ch
}

// runInstall installs the library, package, or binary associated with pkg,
// which is relative to $GOROOT/src.
func runInstall(pkg string, ch chan struct{}) {
	if pkg == "net" || pkg == "os/user" || pkg == "crypto/x509" {
		fatalf("go_bootstrap cannot depend on cgo package %s", pkg)
	}

	// Because we overwrite the build action with the install action below,
	// a1 may already be an install action fetched from the "build" cache key,
	// and the caller just doesn't realize.
	if strings.HasSuffix(a1.Mode, "-install") {
		if a1.buggyInstall && mode == ModeInstall {
			//  Congratulations! The buggy install is now a proper install.
			a1.buggyInstall = false
		}
		return a1
	}

// In earlier versions of Go, 'go get' was used to build and install packages.
// Now, 'go get' is dedicated to adjusting dependencies in go.mod. 'go install'
// may be used to build and install commands instead. When a version is specified,
// 'go install' runs in module-aware mode and ignores the go.mod file in the
// current directory. For example:
//
//	go install example.com/pkg@v1.2.3
//	go install example.com/pkg@latest
//

The -vettool=prog flag selects a different analysis tool with alternative
or additional checks.
For example, the 'shadow' analyzer can be built and run using these commands:

  go install golang.org/x/tools/go/analysis/passes/shadow/cmd/shadow@latest
  go vet -vettool=$(which shadow)

The build flags supported by go vet are those that control package resolution

directory, and MAINFILE is the base name of any Go source
file in the directory that is not included when building
the package.

The -i flag causes clean to remove the corresponding installed
archive or binary (what 'go install' would create).

The -n flag causes clean to print the remove commands it would execute,
but not run them.

The -r flag causes clean to be applied recursively to all the

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

	# GOPATH with p1 in d2, p2 in d2
	env GOPATH=$WORK${/}d1${:}$WORK${/}d2

	# build & install p1
	env
	go install -i p1
	! stale p1
	! stale p2

	# modify p2 - p1 should appear stale
	cp $WORK/p2x.go $WORK/d2/src/p2/p2.go
	stale p1 p2

	# build & install p1 again
	go install -i p11
	! stale p1
	! stale p2

	-- $WORK/d1/src/p1/p1.go --
	package p1
	import "p2"

	buildcmd := []string{"go", "install", "-x", "-buildmode=c-shared", "-installsuffix", "testcshared", "./libgo"}

	cmd := exec.Command(buildcmd[0], buildcmd[1:]...)
	cmd.Dir = filepath.Join(tmpdir, "src", "testcshared")
	env := append(cmd.Environ(),
		"GOPATH="+tmpdir,
		"GOBIN="+filepath.Join(tmpdir, "bin"),
		"GO111MODULE=off", // 'go install' only works in GOPATH mode
	)
	cmd.Env = env

		package main
		func main() {}`)
	tg.setenv("GOPATH", tg.path("."))
	tg.run("install", "-tags", "mytag", "example/a", "example/b")
	tg.wantExecutable(tg.path("bin/a"+exeSuffix), "go install example/a example/b did not install binaries")
	tg.wantExecutable(tg.path("bin/b"+exeSuffix), "go install example/a example/b did not install binaries")
	tg.must(os.Remove(tg.path("bin/a" + exeSuffix)))

		if cfg.BuildContext.GOOS != runtime.GOOS || cfg.BuildContext.GOARCH != runtime.GOARCH {
			// Install cross-compiled binaries to subdirectories of bin.
			elem = full
		}
		if p.Internal.Build.BinDir == "" && cfg.ModulesEnabled {
			p.Internal.Build.BinDir = modload.BinDir()
		}
		if p.Internal.Build.BinDir != "" {
			// Install to GOBIN or bin of GOPATH entry.
			p.Target = filepath.Join(p.Internal.Build.BinDir, elem)