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.
`,

	// The link action ID did not include the full main build ID,
	// even though the full main build ID is written into the
	// eventual binary. That caused the following install to
	// be a no-op, thinking the gofmt binary was up-to-date,
	// even though .Stale could see it was not.
	tg.tempFile("src/m/main.go", "package main /* c2 */; func main() {}\n")
	tg.run("install", "-x", "m")
	tg.run("list", "-f", "{{.Stale}}", "m")

		return StalePath
	}
	if p.Goroot && strings.HasPrefix(p.ImportPath, "cmd/") && p.Name == "main" {
		switch p.ImportPath {
		case "cmd/go", "cmd/gofmt":
			return ToBin
		}
		return ToTool
	}
	return ToBin
}

var cgoExclude = map[string]bool{
	"runtime/cgo": true,
}

var cgoSyscallExclude = map[string]bool{