| // Copyright 2021 The Go Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style |
| // license that can be found in the LICENSE file. |
| |
| package conversions |
| |
| import "unsafe" |
| |
| // "x is assignable to T" |
| // - tested via assignability tests |
| |
| // "x's type and T have identical underlying types if tags are ignored" |
| |
| func _[X ~int, T ~int](x X) T { return T(x) } |
| func _[X struct{f int "foo"}, T struct{f int "bar"}](x X) T { return T(x) } |
| |
| type Foo struct{f int "foo"} |
| type Bar struct{f int "bar"} |
| type Far struct{f float64 } |
| |
| func _[X Foo, T Bar](x X) T { return T(x) } |
| func _[X Foo|Bar, T Bar](x X) T { return T(x) } |
| func _[X Foo, T Foo|Bar](x X) T { return T(x) } |
| func _[X Foo, T Far](x X) T { return T(x /* ERROR cannot convert x \(variable of type X constrained by Foo\) to T\n\tcannot convert Foo \(in X\) to Far \(in T\) */ ) } |
| |
| // "x's type and T are unnamed pointer types and their pointer base types |
| // have identical underlying types if tags are ignored" |
| |
| func _[X ~*Foo, T ~*Bar](x X) T { return T(x) } |
| func _[X ~*Foo|~*Bar, T ~*Bar](x X) T { return T(x) } |
| func _[X ~*Foo, T ~*Foo|~*Bar](x X) T { return T(x) } |
| func _[X ~*Foo, T ~*Far](x X) T { return T(x /* ERROR cannot convert x \(variable of type X constrained by ~\*Foo\) to T\n\tcannot convert \*Foo \(in X\) to \*Far \(in T\) */ ) } |
| |
| // Verify that the defined types in constraints are considered for the rule above. |
| |
| type ( |
| B int |
| C int |
| X0 *B |
| T0 *C |
| ) |
| |
| func _(x X0) T0 { return T0(x /* ERROR cannot convert */ ) } // non-generic reference |
| func _[X X0, T T0](x X) T { return T(x /* ERROR cannot convert */ ) } |
| func _[T T0](x X0) T { return T(x /* ERROR cannot convert */ ) } |
| func _[X X0](x X) T0 { return T0(x /* ERROR cannot convert */ ) } |
| |
| // "x's type and T are both integer or floating point types" |
| |
| func _[X Integer, T Integer](x X) T { return T(x) } |
| func _[X Unsigned, T Integer](x X) T { return T(x) } |
| func _[X Float, T Integer](x X) T { return T(x) } |
| |
| func _[X Integer, T Unsigned](x X) T { return T(x) } |
| func _[X Unsigned, T Unsigned](x X) T { return T(x) } |
| func _[X Float, T Unsigned](x X) T { return T(x) } |
| |
| func _[X Integer, T Float](x X) T { return T(x) } |
| func _[X Unsigned, T Float](x X) T { return T(x) } |
| func _[X Float, T Float](x X) T { return T(x) } |
| |
| func _[X, T Integer|Unsigned|Float](x X) T { return T(x) } |
| func _[X, T Integer|~string](x X) T { return T(x /* ERROR cannot convert x \(variable of type X constrained by Integer\|~string\) to T\n\tcannot convert string \(in X\) to int \(in T\) */ ) } |
| |
| // "x's type and T are both complex types" |
| |
| func _[X, T Complex](x X) T { return T(x) } |
| func _[X, T Float|Complex](x X) T { return T(x /* ERROR cannot convert x \(variable of type X constrained by Float\|Complex\) to T\n\tcannot convert float32 \(in X\) to complex64 \(in T\) */ ) } |
| |
| // "x is an integer or a slice of bytes or runes and T is a string type" |
| |
| type myInt int |
| type myString string |
| |
| func _[T ~string](x int) T { return T(x) } |
| func _[T ~string](x myInt) T { return T(x) } |
| func _[X Integer](x X) string { return string(x) } |
| func _[X Integer](x X) myString { return myString(x) } |
| func _[X Integer](x X) *string { return (*string)(x /* ERROR cannot convert x \(variable of type X constrained by Integer\) to \*string\n\tcannot convert int \(in X\) to \*string */ ) } |
| |
| func _[T ~string](x []byte) T { return T(x) } |
| func _[T ~string](x []rune) T { return T(x) } |
| func _[X ~[]byte, T ~string](x X) T { return T(x) } |
| func _[X ~[]rune, T ~string](x X) T { return T(x) } |
| func _[X Integer|~[]byte|~[]rune, T ~string](x X) T { return T(x) } |
| func _[X Integer|~[]byte|~[]rune, T ~*string](x X) T { return T(x /* ERROR cannot convert x \(variable of type X constrained by Integer\|~\[\]byte\|~\[\]rune\) to T\n\tcannot convert int \(in X\) to \*string \(in T\) */ ) } |
| |
| // "x is a string and T is a slice of bytes or runes" |
| |
| func _[T ~[]byte](x string) T { return T(x) } |
| func _[T ~[]rune](x string) T { return T(x) } |
| func _[T ~[]rune](x *string) T { return T(x /* ERROR cannot convert x \(variable of type \*string\) to T\n\tcannot convert \*string to \[\]rune \(in T\) */ ) } |
| |
| func _[X ~string, T ~[]byte](x X) T { return T(x) } |
| func _[X ~string, T ~[]rune](x X) T { return T(x) } |
| func _[X ~string, T ~[]byte|~[]rune](x X) T { return T(x) } |
| func _[X ~*string, T ~[]byte|~[]rune](x X) T { return T(x /* ERROR cannot convert x \(variable of type X constrained by ~\*string\) to T\n\tcannot convert \*string \(in X\) to \[\]byte \(in T\) */ ) } |
| |
| // package unsafe: |
| // "any pointer or value of underlying type uintptr can be converted into a unsafe.Pointer" |
| |
| type myUintptr uintptr |
| |
| func _[X ~uintptr](x X) unsafe.Pointer { return unsafe.Pointer(x) } |
| func _[T unsafe.Pointer](x myUintptr) T { return T(x) } |
| func _[T unsafe.Pointer](x int64) T { return T(x /* ERROR cannot convert x \(variable of type int64\) to T\n\tcannot convert int64 to unsafe\.Pointer \(in T\) */ ) } |
| |
| // "and vice versa" |
| |
| func _[T ~uintptr](x unsafe.Pointer) T { return T(x) } |
| func _[X unsafe.Pointer](x X) uintptr { return uintptr(x) } |
| func _[X unsafe.Pointer](x X) myUintptr { return myUintptr(x) } |
| func _[X unsafe.Pointer](x X) int64 { return int64(x /* ERROR cannot convert x \(variable of type X constrained by unsafe\.Pointer\) to int64\n\tcannot convert unsafe\.Pointer \(in X\) to int64 */ ) } |
| |
| // "x is a slice, T is a pointer-to-array type, |
| // and the slice and array types have identical element types." |
| |
| func _[X ~[]E, T ~*[10]E, E any](x X) T { return T(x) } |
| func _[X ~[]E, T ~[10]E, E any](x X) T { return T(x /* ERROR cannot convert x \(variable of type X constrained by ~\[\]E\) to T\n\tcannot convert \[\]E \(in X\) to \[10\]E \(in T\) */ ) } |
| |
| // ---------------------------------------------------------------------------- |
| // The following declarations can be replaced by the exported types of the |
| // constraints package once all builders support importing interfaces with |
| // type constraints. |
| |
| type Signed interface { |
| ~int | ~int8 | ~int16 | ~int32 | ~int64 |
| } |
| |
| type Unsigned interface { |
| ~uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 | ~uintptr |
| } |
| |
| type Integer interface { |
| Signed | Unsigned |
| } |
| |
| type Float interface { |
| ~float32 | ~float64 |
| } |
| |
| type Complex interface { |
| ~complex64 | ~complex128 |
| } |