var i = 1<<s                   // 1 has type int
var j int32 = 1<<s             // 1 has type int32; j == 0
var k = uint64(1<<s)           // 1 has type uint64; k == 1<<33
var m int = 1.0<<s             // 1.0 has type int; m == 1<<33
var n = 1.0<<s == j            // 1.0 has type int32; n == true
var o = 1<<s == 2<<s           // 1 and 2 have type int; o == false

or variables, are provided in _cgo_gotypes.go.

Here is a _cgo_gotypes.go containing definitions for needed C types:

	type _Ctype_char int8
	type _Ctype_int int32
	type _Ctype_void [0]byte

The _cgo_gotypes.go file also contains the definitions of the
functions. They all have similar bodies that invoke runtime·cgocall

pkg unicode/utf16, func RuneLen(int32) int #44940...

// Range: -128 through 127.
type int8 int8

// int16 is the set of all signed 16-bit integers.
// Range: -32768 through 32767.
type int16 int16

// int32 is the set of all signed 32-bit integers.
// Range: -2147483648 through 2147483647.
type int32 int32

// int64 is the set of all signed 64-bit integers.
// Range: -9223372036854775808 through 9223372036854775807.
type int64 int64

var i = 1<<s                   // 1 has type int
var j int32 = 1<<s             // 1 has type int32; j == 0
var k = uint64(1<<s)           // 1 has type uint64; k == 1<<33
var m int = 1.0<<s             // 1.0 has type int; m == 1<<33
var n = 1.0<<s == j            // 1.0 has type int32; n == true
var o = 1<<s == 2<<s           // 1 and 2 have type int; o == false

			s = "ideal-string"
		case types.UntypedNil:
			panic("should never see untyped nil type")
		default:
			switch s {
			case "byte":
				s = "uint8"
			case "rune":
				s = "int32"
			}
		}
		buf.WriteString(s)

	case *types.Array:
		fmt.Fprintf(buf, "[%d]", typ.Len())
		w.writeType(buf, typ.Elem())

	case *types.Slice:
		buf.WriteString("[]")

		}
	}
	h.AccessTime = statAtime(sys)
	h.ChangeTime = statCtime(sys)

	// Best effort at populating Devmajor and Devminor.
	if h.Typeflag == TypeChar || h.Typeflag == TypeBlock {
		dev := uint64(sys.Rdev) // May be int32 or uint32
		switch runtime.GOOS {
		case "aix":
			var major, minor uint32
			major = uint32((dev & 0x3fffffff00000000) >> 32)
			minor = uint32((dev & 0x00000000ffffffff) >> 0)