1 // Copyright 2013 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 vardecl
6
7 // Prerequisites.
8 import "math"
9 func f() {}
10 func g() (x, y int) { return }
11 var m map[string]int
12
13 // Var decls must have a type or an initializer.
14 var _ int
15 var _, _ int
16
17 // The first error message is produced by the parser.
18 // In a real-world scenario, the type-checker would not be run
19 // in this case and the 2nd error message would not appear.
20 var _ /* ERROR "missing variable type" */ /* ERROR "missing type or init expr" */
21 var _ /* ERROR "missing variable type" */ /* ERROR "missing type or init expr" */, _
22 var _ /* ERROR "missing variable type" */ /* ERROR "missing type or init expr" */, _, _
23
24 // The initializer must be an expression.
25 var _ = int /* ERROR "not an expression" */
26 var _ = f /* ERROR "used as value" */ ()
27
28 // Identifier and expression arity must match.
29 var _, _ = 1, 2
30 var _ = 1, 2 /* ERROR "extra init expr 2" */
31 var _, _ = 1 /* ERROR "cannot initialize [0-9]+ variables with [0-9]+ values" */
32 var _, _, _ /* ERROR "missing init expr for _" */ = 1, 2
33
34 var _ = g /* ERROR "2-valued g" */ ()
35 var _, _ = g()
36 var _, _, _ = g /* ERROR "cannot initialize [0-9]+ variables with [0-9]+ values" */ ()
37
38 var _ = m["foo"]
39 var _, _ = m["foo"]
40 var _, _, _ = m /* ERROR "cannot initialize [0-9]+ variables with [0-9]+ values" */ ["foo"]
41
42 var _, _ int = 1, 2
43 var _ int = 1, 2 /* ERROR "extra init expr 2" */
44 var _, _ int = 1 /* ERROR "cannot initialize [0-9]+ variables with [0-9]+ values" */
45 var _, _, _ /* ERROR "missing init expr for _" */ int = 1, 2
46
47 var (
48 _, _ = 1, 2
49 _ = 1, 2 /* ERROR "extra init expr 2" */
50 _, _ = 1 /* ERROR "cannot initialize [0-9]+ variables with [0-9]+ values" */
51 _, _, _ /* ERROR "missing init expr for _" */ = 1, 2
52
53 _ = g /* ERROR "2-valued g" */ ()
54 _, _ = g()
55 _, _, _ = g /* ERROR "cannot initialize [0-9]+ variables with [0-9]+ values" */ ()
56
57 _ = m["foo"]
58 _, _ = m["foo"]
59 _, _, _ = m /* ERROR "cannot initialize [0-9]+ variables with [0-9]+ values" */ ["foo"]
60
61 _, _ int = 1, 2
62 _ int = 1, 2 /* ERROR "extra init expr 2" */
63 _, _ int = 1 /* ERROR "cannot initialize [0-9]+ variables with [0-9]+ values" */
64 _, _, _ /* ERROR "missing init expr for _" */ int = 1, 2
65 )
66
67 // Variables declared in function bodies must be 'used'.
68 type T struct{}
69 func (r T) _(a, b, c int) (u, v, w int) {
70 var x1 /* ERROR "declared but not used" */ int
71 var x2 /* ERROR "declared but not used" */ int
72 x1 = 1
73 (x2) = 2
74
75 y1 /* ERROR "declared but not used" */ := 1
76 y2 /* ERROR "declared but not used" */ := 2
77 y1 = 1
78 (y1) = 2
79
80 {
81 var x1 /* ERROR "declared but not used" */ int
82 var x2 /* ERROR "declared but not used" */ int
83 x1 = 1
84 (x2) = 2
85
86 y1 /* ERROR "declared but not used" */ := 1
87 y2 /* ERROR "declared but not used" */ := 2
88 y1 = 1
89 (y1) = 2
90 }
91
92 if x /* ERROR "declared but not used" */ := 0; a < b {}
93
94 switch x /* ERROR "declared but not used" */, y := 0, 1; a {
95 case 0:
96 _ = y
97 case 1:
98 x /* ERROR "declared but not used" */ := 0
99 }
100
101 var t interface{}
102 switch t /* ERROR "declared but not used" */ := t.(type) {}
103
104 switch t /* ERROR "declared but not used" */ := t.(type) {
105 case int:
106 }
107
108 switch t /* ERROR "declared but not used" */ := t.(type) {
109 case int:
110 case float32, complex64:
111 t = nil
112 }
113
114 switch t := t.(type) {
115 case int:
116 case float32, complex64:
117 _ = t
118 }
119
120 switch t := t.(type) {
121 case int:
122 case float32:
123 case string:
124 _ = func() string {
125 return t
126 }
127 }
128
129 switch t := t; t /* ERROR "declared but not used" */ := t.(type) {}
130
131 var z1 /* ERROR "declared but not used" */ int
132 var z2 int
133 _ = func(a, b, c int) (u, v, w int) {
134 z1 = a
135 (z1) = b
136 a = z2
137 return
138 }
139
140 var s []int
141 var i /* ERROR "declared but not used" */ , j int
142 for i, j = range s {
143 _ = j
144 }
145
146 for i, j /* ERROR "declared but not used" */ := range s {
147 _ = func() int {
148 return i
149 }
150 }
151 return
152 }
153
154 // Unused variables in function literals must lead to only one error (issue #22524).
155 func _() {
156 _ = func() {
157 var x /* ERROR declared but not used */ int
158 }
159 }
160
161 // Invalid (unused) expressions must not lead to spurious "declared but not used errors"
162 func _() {
163 var a, b, c int
164 var x, y int
165 x, y = a /* ERROR cannot assign [0-9]+ values to [0-9]+ variables */ , b, c
166 _ = x
167 _ = y
168 }
169
170 func _() {
171 var x int
172 return x /* ERROR no result values expected */
173 return math /* ERROR no result values expected */ .Sin(0)
174 }
175
176 func _() int {
177 var x, y int
178 return /* ERROR wrong number of return values */ x, y
179 }
180
181 // Short variable declarations must declare at least one new non-blank variable.
182 func _() {
183 _ := /* ERROR no new variables */ 0
184 _, a := 0, 1
185 _, a := /* ERROR no new variables */ 0, 1
186 _, a, b := 0, 1, 2
187 _, _, _ := /* ERROR no new variables */ 0, 1, 2
188
189 _ = a
190 _ = b
191 }
192
193 // Test case for variables depending on function literals (see also #22992).
194 var A /* ERROR initialization cycle */ = func() int { return A }()
195
196 func _() {
197 // The function literal below must not see a.
198 var a = func() int { return a /* ERROR "undeclared name" */ }()
199 var _ = func() int { return a }()
200
201 // The function literal below must not see x, y, or z.
202 var x, y, z = 0, 1, func() int { return x /* ERROR "undeclared name" */ + y /* ERROR "undeclared name" */ + z /* ERROR "undeclared name" */ }()
203 _, _, _ = x, y, z
204 }
205
206 // TODO(gri) consolidate other var decl checks in this file
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