1 // Copyright 2019 The Go Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style
3 // license that can be found in the LICENSE file.
4
5 package p
6
7 type List[E any] []E
8 var _ List[List[List[int]]]
9 var _ List[List[List[int]]] = []List[List[int]]{}
10
11 type (
12 T1[P1 any] struct {
13 f1 T2[P1, float32]
14 }
15
16 T2[P2, P3 any] struct {
17 f2 P2
18 f3 P3
19 }
20 )
21
22 func _() {
23 var x1 T1[int]
24 var x2 T2[int, float32]
25
26 x1.f1.f2 = 0
27 x1.f1 = x2
28 }
29
30 type T3[P any] T1[T2[P, P]]
31
32 func _() {
33 var x1 T3[int]
34 var x2 T2[int, int]
35 x1.f1.f2 = x2
36 }
37
38 func f[P any] (x P) List[P] {
39 return List[P]{x}
40 }
41
42 var (
43 _ []int = f(0)
44 _ []float32 = f[float32](10)
45 _ List[complex128] = f(1i)
46 _ []List[int] = f(List[int]{})
47 _ List[List[int]] = []List[int]{}
48 _ = []List[int]{}
49 )
50
51 // Parameterized types with methods
52
53 func (l List[E]) Head() (_ E, _ bool) {
54 if len(l) > 0 {
55 return l[0], true
56 }
57 return
58 }
59
60 // A test case for instantiating types with other types (extracted from map.go2)
61
62 type Pair[K any] struct {
63 key K
64 }
65
66 type Receiver[T any] struct {
67 values T
68 }
69
70 type Iterator[K any] struct {
71 r Receiver[Pair[K]]
72 }
73
74 func Values [T any] (r Receiver[T]) T {
75 return r.values
76 }
77
78 func (it Iterator[K]) Next() K {
79 return Values[Pair[K]](it.r).key
80 }
81
82 // A more complex test case testing type bounds (extracted from linalg.go2 and reduced to essence)
83
84 type NumericAbs[T any] interface {
85 Abs() T
86 }
87
88 func AbsDifference[T NumericAbs[T]](x T)
89
90 type OrderedAbs[T any] T
91
92 func (a OrderedAbs[T]) Abs() OrderedAbs[T]
93
94 func OrderedAbsDifference[T any](x T) {
95 AbsDifference(OrderedAbs[T](x))
96 }
97
98 // same code, reduced to essence
99
100 func g[P interface{ m() P }](x P)
101
102 type T4[P any] P
103
104 func (_ T4[P]) m() T4[P]
105
106 func _[Q any](x Q) {
107 g(T4[Q](x))
108 }
109
110 // Another test case that caused problems in the past
111
112 type T5[_ interface { a() }, _ interface{}] struct{}
113
114 type A[P any] struct{ x P }
115
116 func (_ A[P]) a() {}
117
118 var _ T5[A[int], int]
119
120 // Invoking methods with parameterized receiver types uses
121 // type inference to determine the actual type arguments matching
122 // the receiver type parameters from the actual receiver argument.
123 // Go does implicit address-taking and dereferenciation depending
124 // on the actual receiver and the method's receiver type. To make
125 // type inference work, the type-checker matches "pointer-ness"
126 // of the actual receiver and the method's receiver type.
127 // The following code tests this mechanism.
128
129 type R1[A any] struct{}
130 func (_ R1[A]) vm()
131 func (_ *R1[A]) pm()
132
133 func _[T any](r R1[T], p *R1[T]) {
134 r.vm()
135 r.pm()
136 p.vm()
137 p.pm()
138 }
139
140 type R2[A, B any] struct{}
141 func (_ R2[A, B]) vm()
142 func (_ *R2[A, B]) pm()
143
144 func _[T any](r R2[T, int], p *R2[string, T]) {
145 r.vm()
146 r.pm()
147 p.vm()
148 p.pm()
149 }
150
151 // An interface can (explicitly) declare at most one type list.
152 type _ interface {
153 m0()
154 type int, string, bool
155 type /* ERROR multiple type lists */ float32, float64
156 m1()
157 m2()
158 type /* ERROR multiple type lists */ complex64, complex128
159 type /* ERROR multiple type lists */ rune
160 }
161
162 // Interface type lists may contain each type at most once.
163 // (If there are multiple lists, we assume the author intended
164 // for them to be all in a single list, and we report the error
165 // as well.)
166 type _ interface {
167 type int, int /* ERROR duplicate type int */
168 type /* ERROR multiple type lists */ int /* ERROR duplicate type int */
169 }
170
171 type _ interface {
172 type struct{f int}, struct{g int}, struct /* ERROR duplicate type */ {f int}
173 }
174
175 // Interface type lists can contain any type, incl. *Named types.
176 // Verify that we use the underlying type to compute the operational type.
177 type MyInt int
178 func add1[T interface{type MyInt}](x T) T {
179 return x + 1
180 }
181
182 type MyString string
183 func double[T interface{type MyInt, MyString}](x T) T {
184 return x + x
185 }
186
187 // Embedding of interfaces with type lists leads to interfaces
188 // with type lists that are the intersection of the embedded
189 // type lists.
190
191 type E0 interface {
192 type int, bool, string
193 }
194
195 type E1 interface {
196 type int, float64, string
197 }
198
199 type E2 interface {
200 type float64
201 }
202
203 type I0 interface {
204 E0
205 }
206
207 func f0[T I0]()
208 var _ = f0[int]
209 var _ = f0[bool]
210 var _ = f0[string]
211 var _ = f0[float64 /* ERROR does not satisfy I0 */ ]
212
213 type I01 interface {
214 E0
215 E1
216 }
217
218 func f01[T I01]()
219 var _ = f01[int]
220 var _ = f01[bool /* ERROR does not satisfy I0 */ ]
221 var _ = f01[string]
222 var _ = f01[float64 /* ERROR does not satisfy I0 */ ]
223
224 type I012 interface {
225 E0
226 E1
227 E2
228 }
229
230 func f012[T I012]()
231 var _ = f012[int /* ERROR does not satisfy I012 */ ]
232 var _ = f012[bool /* ERROR does not satisfy I012 */ ]
233 var _ = f012[string /* ERROR does not satisfy I012 */ ]
234 var _ = f012[float64 /* ERROR does not satisfy I012 */ ]
235
236 type I12 interface {
237 E1
238 E2
239 }
240
241 func f12[T I12]()
242 var _ = f12[int /* ERROR does not satisfy I12 */ ]
243 var _ = f12[bool /* ERROR does not satisfy I12 */ ]
244 var _ = f12[string /* ERROR does not satisfy I12 */ ]
245 var _ = f12[float64]
246
247 type I0_ interface {
248 E0
249 type int
250 }
251
252 func f0_[T I0_]()
253 var _ = f0_[int]
254 var _ = f0_[bool /* ERROR does not satisfy I0_ */ ]
255 var _ = f0_[string /* ERROR does not satisfy I0_ */ ]
256 var _ = f0_[float64 /* ERROR does not satisfy I0_ */ ]
257
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