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package main
// Tests of interface conversions and type assertions.
type I0 interface {
}
type I1 interface {
f()
}
type I2 interface {
f()
g()
}
type C0 struct{}
type C1 struct{}
func (C1) f() {}
type C2 struct{}
func (C2) f() {}
func (C2) g() {}
func main() {
var i0 I0
var i1 I1
var i2 I2
// Nil always causes a type assertion to fail, even to the
// same type.
if _, ok := i0.(I0); ok {
panic("nil i0.(I0) succeeded")
}
if _, ok := i1.(I1); ok {
panic("nil i1.(I1) succeeded")
}
if _, ok := i2.(I2); ok {
panic("nil i2.(I2) succeeded")
}
// Conversions can't fail, even with nil.
_ = I0(i0)
_ = I0(i1)
_ = I1(i1)
_ = I0(i2)
_ = I1(i2)
_ = I2(i2)
// Non-nil type assertions pass or fail based on the concrete type.
i1 = C1{}
if _, ok := i1.(I0); !ok {
panic("C1 i1.(I0) failed")
}
if _, ok := i1.(I1); !ok {
panic("C1 i1.(I1) failed")
}
if _, ok := i1.(I2); ok {
panic("C1 i1.(I2) succeeded")
}
i1 = C2{}
if _, ok := i1.(I0); !ok {
panic("C2 i1.(I0) failed")
}
if _, ok := i1.(I1); !ok {
panic("C2 i1.(I1) failed")
}
if _, ok := i1.(I2); !ok {
panic("C2 i1.(I2) failed")
}
// Conversions can't fail.
i1 = C1{}
if I0(i1) == nil {
panic("C1 I0(i1) was nil")
}
if I1(i1) == nil {
panic("C1 I1(i1) was nil")
}
}
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