mirror of
https://github.com/golang/go
synced 2024-11-24 07:40:17 -07:00
428ea6865c
A struct with a single field was considered as equivalent to the field type, which is incorrect is the field is blank. Fields with padding could make the compiler think some types are comparable when they are not. Fixes #5698. R=rsc, golang-dev, daniel.morsing, bradfitz, gri, r CC=golang-dev https://golang.org/cl/10271046
76 lines
1.8 KiB
Go
76 lines
1.8 KiB
Go
// errorcheck
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// Copyright 2010 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Verify that incorrect comparisons are detected.
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// Does not compile.
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package main
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func use(bool) {}
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type T1 *int
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type T2 *int
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type T3 struct{ z []int }
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var t3 T3
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type T4 struct { _ []int; a float64 }
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var t4 T4
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func main() {
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// Arguments to comparison must be
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// assignable one to the other (or vice versa)
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// so chan int can be compared against
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// directional channels but channel of different
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// direction cannot be compared against each other.
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var c1 chan<- int
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var c2 <-chan int
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var c3 chan int
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use(c1 == c2) // ERROR "invalid operation|incompatible"
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use(c2 == c1) // ERROR "invalid operation|incompatible"
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use(c1 == c3)
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use(c2 == c2)
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use(c3 == c1)
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use(c3 == c2)
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// Same applies to named types.
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var p1 T1
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var p2 T2
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var p3 *int
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use(p1 == p2) // ERROR "invalid operation|incompatible"
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use(p2 == p1) // ERROR "invalid operation|incompatible"
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use(p1 == p3)
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use(p2 == p2)
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use(p3 == p1)
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use(p3 == p2)
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// Comparison of structs should have a good message
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use(t3 == t3) // ERROR "struct|expected"
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use(t4 == t4) // ERROR "cannot be compared|non-comparable"
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// Slices, functions, and maps too.
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var x []int
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var f func()
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var m map[int]int
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use(x == x) // ERROR "slice can only be compared to nil"
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use(f == f) // ERROR "func can only be compared to nil"
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use(m == m) // ERROR "map can only be compared to nil"
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// Comparison with interface that cannot return true
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// (would panic).
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var i interface{}
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use(i == x) // ERROR "invalid operation"
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use(x == i) // ERROR "invalid operation"
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use(i == f) // ERROR "invalid operation"
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use(f == i) // ERROR "invalid operation"
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use(i == m) // ERROR "invalid operation"
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use(m == i) // ERROR "invalid operation"
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}
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