// AVX2GATHER mask/index/dest #UD cases.
	VPGATHERQQ Y2, (BP)(X2*2), Y2   // ERROR "mask, index, and destination registers should be distinct"
	VPGATHERQQ Y2, (BP)(X2*2), Y7   // ERROR "mask, index, and destination registers should be distinct"
	VPGATHERQQ Y2, (BP)(X7*2), Y2   // ERROR "mask, index, and destination registers should be distinct"

pkg syscall (freebsd-386), const MAP_ALIGNED_SUPER = 16777216
pkg syscall (freebsd-386), const MAP_ALIGNED_SUPER ideal-int
pkg syscall (freebsd-386), const MAP_ALIGNMENT_MASK = -16777216
pkg syscall (freebsd-386), const MAP_ALIGNMENT_MASK ideal-int
pkg syscall (freebsd-386), const MAP_ALIGNMENT_SHIFT = 24
pkg syscall (freebsd-386), const MAP_ALIGNMENT_SHIFT ideal-int
pkg syscall (freebsd-386), const MSG_CMSG_CLOEXEC = 262144

pkg syscall (netbsd-arm64-cgo), const IPV6_FAITH ideal-int
pkg syscall (netbsd-arm64-cgo), const IPV6_FLOWINFO_MASK = 4294967055
pkg syscall (netbsd-arm64-cgo), const IPV6_FLOWINFO_MASK ideal-int
pkg syscall (netbsd-arm64-cgo), const IPV6_FLOWLABEL_MASK = 4294905600
pkg syscall (netbsd-arm64-cgo), const IPV6_FLOWLABEL_MASK ideal-int
pkg syscall (netbsd-arm64-cgo), const IPV6_FRAGTTL = 120

	if len(b) > 0 && b[0]&0x80 != 0 {
		// Handling negative numbers relies on the following identity:
		//	-a-1 == ^a
		//
		// If the number is negative, we use an inversion mask to invert the
		// data bytes and treat the value as an unsigned number.
		var inv byte // 0x00 if positive or zero, 0xff if negative
		if b[0]&0x40 != 0 {
			inv = 0xff
		}

		var x uint64

pkg syscall (freebsd-arm64), const BPF_T_FAST ideal-int
pkg syscall (freebsd-arm64), const BPF_T_FLAG_MASK = 768
pkg syscall (freebsd-arm64), const BPF_T_FLAG_MASK ideal-int
pkg syscall (freebsd-arm64), const BPF_T_FORMAT_MASK = 3
pkg syscall (freebsd-arm64), const BPF_T_FORMAT_MASK ideal-int
pkg syscall (freebsd-arm64), const BPF_T_MICROTIME = 0
pkg syscall (freebsd-arm64), const BPF_T_MICROTIME ideal-int

pkg syscall (darwin-arm64), const IPV6_FAITH ideal-int
pkg syscall (darwin-arm64), const IPV6_FLOWINFO_MASK = 4294967055
pkg syscall (darwin-arm64), const IPV6_FLOWINFO_MASK ideal-int
pkg syscall (darwin-arm64), const IPV6_FLOWLABEL_MASK = 4294905600
pkg syscall (darwin-arm64), const IPV6_FLOWLABEL_MASK ideal-int
pkg syscall (darwin-arm64), const IPV6_FRAGTTL = 120
pkg syscall (darwin-arm64), const IPV6_FRAGTTL ideal-int

Four * 100   // product 400 cannot be represented as an int8 (type of Four)
</pre>

<p>
The mask used by the unary bitwise complement operator <code>^</code> matches
the rule for non-constants: the mask is all 1s for unsigned constants
and -1 for signed and untyped constants.
</p>

<pre>
^1         // untyped integer constant, equal to -2

pkg syscall (freebsd-386), const BPF_T_FAST ideal-int
pkg syscall (freebsd-386), const BPF_T_FLAG_MASK = 768
pkg syscall (freebsd-386), const BPF_T_FLAG_MASK ideal-int
pkg syscall (freebsd-386), const BPF_T_FORMAT_MASK = 3
pkg syscall (freebsd-386), const BPF_T_FORMAT_MASK ideal-int
pkg syscall (freebsd-386), const BPF_T_MICROTIME = 0
pkg syscall (freebsd-386), const BPF_T_MICROTIME ideal-int

pkg syscall (darwin-386), const IPV6_DEFHLIM ideal-int
pkg syscall (darwin-386), const IPV6_FAITH ideal-int
pkg syscall (darwin-386), const IPV6_FLOWINFO_MASK ideal-int
pkg syscall (darwin-386), const IPV6_FLOWLABEL_MASK ideal-int
pkg syscall (darwin-386), const IPV6_FRAGTTL ideal-int
pkg syscall (darwin-386), const IPV6_FW_ADD ideal-int
pkg syscall (darwin-386), const IPV6_FW_DEL ideal-int

	}
	out, err := cmd.CombinedOutput()
	if string(out) != "OK\n" {
		t.Errorf("%s", string(out))
	}
	if err != nil {
		t.Errorf("%s", err)
	}
}

func mustHaveCxx(t *testing.T) {
	// Ask the go tool for the CXX it's configured to use.
	cxx, err := exec.Command("go", "env", "CXX").CombinedOutput()
	if err != nil {
		t.Fatalf("go env CXX failed: %s", err)
	}
	args, err := quoted.Split(string(cxx))