// Examples of TopFrame functions include goexit, which appears
	// at the top of a user goroutine stack, and mstart, which appears
	// at the top of a system goroutine stack.
	FuncFlagTopFrame FuncFlag = 1 << iota

	// FuncFlagSPWrite indicates a function that writes an arbitrary value to SP
	// (any write other than adding or subtracting a constant amount).
	// The traceback routines cannot encode such changes into the

// by them is useful for defining GOARCH-specific constants.
//
//go:generate go run gengoarch.go

type ArchFamilyType int

const (
	AMD64 ArchFamilyType = iota
	ARM
	ARM64
	I386
	LOONG64
	MIPS
	MIPS64
	PPC64
	RISCV64
	S390X
	WASM
)

// PtrSize is the size of a pointer in bytes - unsafe.Sizeof(uintptr(0)) but as an ideal constant.

	return w.dot
}

func (w *Writer) closeDot() {
	if w.dot != nil {
		w.dot.Close() // sets w.dot = nil
	}
}

type dotWriter struct {
	w     *Writer
	state int
}

const (
	wstateBegin     = iota // initial state; must be zero
	wstateBeginLine        // beginning of line
	wstateCR               // wrote \r (possibly at end of line)
	wstateData             // writing data in middle of line
)

// statuses.
type traceGoStatus uint8

const (
	traceGoBad traceGoStatus = iota
	traceGoRunnable
	traceGoRunning
	traceGoSyscall
	traceGoWaiting
)

// traceProcStatus is the status of a P.
//
// They mostly correspond to the various P statuses.
type traceProcStatus uint8

const (
	traceProcBad traceProcStatus = iota
	traceProcRunning
	traceProcIdle
	traceProcSyscall

type Prog struct {
	Inst   []Inst
	Start  int // index of start instruction
	NumCap int // number of InstCapture insts in re
}

// An InstOp is an instruction opcode.
type InstOp uint8

const (
	InstAlt InstOp = iota
	InstAltMatch
	InstCapture
	InstEmptyWidth
	InstMatch
	InstFail
	InstNop
	InstRune
	InstRune1
	InstRuneAny
	InstRuneAnyNotNL
)

var instOpNames = []string{
	"InstAlt",
	"InstAltMatch",

// cXORCase can result in large series of identical trie values. This, in turn,
// allows us to better compress the trie blocks.
const (
	cUncased          info = iota // 000
	cTitle                        // 001
	cLower                        // 010
	cUpper                        // 011
	cIgnorableUncased             // 100

	"math"
	"unsafe"
)

// ValueKind is a tag for a metric [Value] which indicates its type.
type ValueKind int

const (
	// KindBad indicates that the Value has no type and should not be used.
	KindBad ValueKind = iota

	// KindUint64 indicates that the type of the Value is a uint64.
	KindUint64

	// KindFloat64 indicates that the type of the Value is a float64.
	KindFloat64

// AlgKind describes the kind of algorithms used for comparing and
// hashing a Type.
type AlgKind int8

//go:generate stringer -type AlgKind -trimprefix A alg.go

const (
	AUNK   AlgKind = iota
	ANOEQ          // Types cannot be compared
	ANOALG         // implies ANOEQ, and in addition has a part that is marked Noalg
	AMEM           // Type can be compared/hashed as regular memory.

	"cmd/go/internal/search"
	"cmd/go/internal/str"
	"cmd/go/internal/trace"
	"cmd/internal/pkgpattern"

	"golang.org/x/mod/module"
)

type stdFilter int8

const (
	omitStd = stdFilter(iota)
	includeStd
)

// matchPackages is like m.MatchPackages, but uses a local variable (rather than
// a global) for tags, can include or exclude packages in the standard library,

func Validate(analyzers []*Analyzer) error {
	// Map each fact type to its sole generating analyzer.
	factTypes := make(map[reflect.Type]*Analyzer)

	// Traverse the Requires graph, depth first.
	const (
		white = iota
		grey
		black
		finished
	)
	color := make(map[*Analyzer]uint8)
	var visit func(a *Analyzer) error
	visit = func(a *Analyzer) error {
		if a == nil {
			return fmt.Errorf("nil *Analyzer")
		}