// The bug happened like this:
//  1. The main binary adds an itab for *json.UnsupportedValueError / error
//     (concrete type / interface type).  This itab goes in hash bucket 0x111.
//  2. The plugin adds that same itab again.  That makes a cycle in the itab
//     chain rooted at hash bucket 0x111.
//  3. The main binary then asks for the itab for *dynamodbstreamsevt.Event /
//     json.Unmarshaler.  This itab happens to also live in bucket 0x111.

	}
	t.add(m)
}

// add adds the given itab to itab table t.
// itabLock must be held.
func (t *itabTableType) add(m *itab) {
	// See comment in find about the probe sequence.
	// Insert new itab in the first empty spot in the probe sequence.
	mask := t.size - 1
	h := itabHashFunc(m.Inter, m.Type) & mask
	for i := uintptr(1); ; i++ {
		p := (**itab)(add(unsafe.Pointer(&t.entries), h*goarch.PtrSize))
		m2 := *p

}

type InterfaceSwitchCacheEntry struct {
	// type of source value (a *Type)
	Typ uintptr
	// case # to dispatch to
	Case int
	// itab to use for resulting case variable (a *runtime.itab)
	Itab uintptr
}

const go122InterfaceSwitchCache = true

func UseInterfaceSwitchCache(goarch string) bool {
	if !go122InterfaceSwitchCache {
		return false
	}

	// representing the asserted type.
	//
	// BUG(mdempsky): If ITab is non-nil, RType may be nil.
	RType Node

	// ITab is an expression that yields a *runtime.itab value
	// representing the asserted type within the assertee expression's
	// original interface type.
	//
	// ITab is only used for assertions (including type switches) from

	M()
	M2()
}

var t T
var e interface{} = &t
var ok = false
var ch = make(chan int)

func main() {
	_, ok = e.(I) // populate itab cache with a false result

	go f() // get itab in a loop

	var i I
	for k := 0; k < 10000; k++ {
		i, ok = e.(I) // read the cached itab
		if ok {
			println("iteration", k, "i =", i, "&t =", &t)
			panic("conversion succeeded")
		}
	}
	<-ch
}

func f() {

package abi

import "unsafe"

// The first word of every non-empty interface type contains an *ITab.
// It records the underlying concrete type (Type), the interface type it
// is implementing (Inter), and some ancillary information.
//
// allocated in non-garbage-collected memory
type ITab struct {
	Inter *InterfaceType
	Type  *Type
	Hash  uint32     // copy of Type.Hash. Used for type switches.

      len
      (Store {t.Elem().PtrTo()} dst ptr mem)))

// interface ops
(ITab (IMake itab _)) => itab
(IData (IMake _ data)) => data

(Load <t> ptr mem) && t.IsInterface() =>
  (IMake
    (Load <typ.Uintptr> ptr mem)
    (Load <typ.BytePtr>
      (OffPtr <typ.BytePtrPtr> [config.PtrSize] ptr)
      mem))
(Store dst (IMake itab data) mem) =>
  (Store {typ.BytePtr}
    (OffPtr <typ.BytePtrPtr> [config.PtrSize] dst)

// from an interface's descriptor word (whether a *runtime._type or
// *runtime.itab pointer).
func typeHashFieldOf(pos src.XPos, itab *ir.UnaryExpr) *ir.SelectorExpr {
	if itab.Op() != ir.OITAB {
		base.Fatalf("expected OITAB, got %v", itab.Op())
	}
	var hashField *types.Field
	if itab.X.Type().IsEmptyInterface() {
		// runtime._type's hash field
		if rtypeHashField == nil {

func (T) m() { println("ok") }

// The compiler used to not pay attention to package for non-exported
// methods when statically constructing itabs. The consequence of this
// was that the call to b.F1(b.T{}) in c.go would create an itab using
// a.T.m instead of b.T.m.
func F1(i interface{ m() }) { i.m() }

// The interface method calling convention depends on interface method
// sets being sorted in the same order across compilation units.  In

}

func isI(x any) {
	_ = x.(I)
}

func test1() {
	defer func() { recover() }()
	ld[bool]() // add <bool,I> itab to binary
	_ = any(false).(I)
}

type B bool

func (B) f() {
}
func (B) g() {
}

func test2() {
	defer func() { recover() }()
	ld[B]() // add <B,I> itab to binary
	_ = any(B(false)).(I)