c := testenv.Command(t, testenv.GoToolPath(t), "build", "-o", exe, "read3.go")
	// Build the test without cgo, so that C library functions don't
	// open descriptors unexpectedly. See issue 25628.
	c.Env = append(os.Environ(), "CGO_ENABLED=0")
	if output, err := c.CombinedOutput(); err != nil {
		t.Logf("go build -o %s read3.go\n%s", exe, output)
		t.Fatalf("go build failed: %v", err)
	}

pkg go/build, method (*NoGoError) Error() string
pkg go/build, method (*Package) IsCommand() bool
pkg go/build, type Context struct
pkg go/build, type Context struct, BuildTags []string
pkg go/build, type Context struct, CgoEnabled bool
pkg go/build, type Context struct, Compiler string
pkg go/build, type Context struct, GOARCH string
pkg go/build, type Context struct, GOOS string
pkg go/build, type Context struct, GOPATH string