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