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package runtime
// This file implements Go interfaces.
// Interfaces are represented as a pair of {typecode, value}, where value can be
// anything (including non-pointers).
import "unsafe"
type _interface struct {
typecode uintptr
value unsafe.Pointer
// Return true iff both interfaces are equal.
func interfaceEqual(x, y _interface) bool {
if x.typecode != y.typecode {
// Different dynamic type so always unequal.
return false
if x.typecode == 0 {
// Both interfaces are nil, so they are equal.
return true
// TODO: depends on reflection.
panic("unimplemented: interface equality")
// interfaceTypeAssert is called when a type assert without comma-ok still
// returns false.
func interfaceTypeAssert(ok bool) {
if !ok {
runtimePanic("type assert failed")
// The following declarations are only used during IR construction. They are
// lowered to inline IR in the interface lowering pass.
// See compiler/interface-lowering.go for details.
type interfaceMethodInfo struct {
signature *uint8 // external *i8 with a name identifying the Go function signature
funcptr uintptr // bitcast from the actual function pointer
type typecodeID struct{}
// Pseudo type used before interface lowering. By using a struct instead of a
// function call, this is simpler to reason about during init interpretation
// than a function call. Also, by keeping the method set around it is easier to
// implement interfaceImplements in the interp package.
type typeInInterface struct {
typecode *typecodeID
methodSet *interfaceMethodInfo // nil or a GEP of an array
// Pseudo function call used during a type assert. It is used during interface
// lowering, to assign the lowest type numbers to the types with the most type
// asserts. Also, it is replaced with const false if this type assert can never
// happen.
func typeAssert(actualType uintptr, assertedType *typecodeID) bool
// Pseudo function call that returns whether a given type implements all methods
// of the given interface.
func interfaceImplements(typecode uintptr, interfaceMethodSet **uint8) bool
// Pseudo function that returns a function pointer to the method to call.
// See the interface lowering pass for how this is lowered to a real call.
func interfaceMethod(typecode uintptr, interfaceMethodSet **uint8, signature *uint8) uintptr
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