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"cannot assign to" compiler errors are very laconic: they never explain why the lhs cannot be assigned to (with one exception, when assigning to a struct field in a map). This change makes them a little more specific, in two more cases: when assigning to a string, or to a const; by giving a very brief reason why the lhs cannot be assigned to. Change-Id: I244cca7fc3c3814e00e0ccadeec62f747c293979 Reviewed-on: https://go-review.googlesource.com/c/go/+/255199 Trust: Alberto Donizetti <alb.donizetti@gmail.com> Run-TryBot: Alberto Donizetti <alb.donizetti@gmail.com> TryBot-Result: Go Bot <gobot@golang.org> Reviewed-by: Matthew Dempsky <mdempsky@google.com>
34 lines
1 KiB
Go
34 lines
1 KiB
Go
// errorcheck
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// Copyright 2020 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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// Test "cannot assign" errors
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package main
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func main() {
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var s string = "hello"
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s[1:2] = "a" // ERROR "cannot assign to .* \(strings are immutable\)"
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s[3] = "b" // ERROR "cannot assign to .* \(strings are immutable\)"
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const n int = 1
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const cs string = "hello"
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n = 2 // ERROR "cannot assign to .* \(declared const\)"
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cs = "hi" // ERROR "cannot assign to .* \(declared const\)"
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true = false // ERROR "cannot assign to .* \(declared const\)"
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var m map[int]struct{ n int }
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m[0].n = 7 // ERROR "cannot assign to struct field .* in map$"
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1 = 7 // ERROR "cannot assign to 1$"
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"hi" = 7 // ERROR `cannot assign to "hi"$`
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nil = 7 // ERROR "cannot assign to nil$"
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len("") = 7 // ERROR `cannot assign to len\(""\)$`
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[]int{} = nil // ERROR "cannot assign to \[\]int\{\}$"
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var x int = 7
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x + 1 = 7 // ERROR "cannot assign to x \+ 1$"
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}
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