mirror of
https://github.com/golang/go
synced 2024-11-18 11:04:42 -07:00
6e3e380923
The allowed conversions before and after are:
type Tstring string
type Tbyte []byte
type Trune []rune
string <-> string // ok
string <-> []byte // ok
string <-> []rune // ok
string <-> Tstring // ok
string <-> Tbyte // was illegal, now ok
string <-> Trune // was illegal, now ok
Tstring <-> string // ok
Tstring <-> []byte // ok
Tstring <-> []rune // ok
Tstring <-> Tstring // ok
Tstring <-> Tbyte // was illegal, now ok
Tstring <-> Trune // was illegal, now ok
Update spec, compiler, tests. Use in a few packages.
We agreed on this a few months ago but never implemented it.
Fixes #1707.
R=golang-dev, gri, r
CC=golang-dev
https://golang.org/cl/5421057
67 lines
2.0 KiB
Go
67 lines
2.0 KiB
Go
// errchk $G -e $D/$F.go
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// Copyright 2009 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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package main
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// explicit conversion of constants is work in progress.
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// the ERRORs in this block are debatable, but they're what
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// the language spec says for now.
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var x1 = string(1)
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var x2 string = string(1)
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var x3 = int(1.5) // ERROR "convert|truncate"
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var x4 int = int(1.5) // ERROR "convert|truncate"
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var x5 = "a" + string(1)
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var x6 = int(1e100) // ERROR "overflow"
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var x7 = float32(1e1000) // ERROR "overflow"
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// implicit conversions merit scrutiny
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var s string
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var bad1 string = 1 // ERROR "conver|incompatible|invalid|cannot"
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var bad2 = s + 1 // ERROR "conver|incompatible|invalid"
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var bad3 = s + 'a' // ERROR "conver|incompatible|invalid"
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var bad4 = "a" + 1 // ERROR "literals|incompatible|convert|invalid"
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var bad5 = "a" + 'a' // ERROR "literals|incompatible|convert|invalid"
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var bad6 int = 1.5 // ERROR "convert|truncate"
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var bad7 int = 1e100 // ERROR "overflow"
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var bad8 float32 = 1e200 // ERROR "overflow"
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// but these implicit conversions are okay
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var good1 string = "a"
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var good2 int = 1.0
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var good3 int = 1e9
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var good4 float64 = 1e20
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// explicit conversion of string is okay
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var _ = []rune("abc")
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var _ = []byte("abc")
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// implicit is not
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var _ []int = "abc" // ERROR "cannot use|incompatible|invalid"
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var _ []byte = "abc" // ERROR "cannot use|incompatible|invalid"
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// named string is okay
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type Tstring string
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var ss Tstring = "abc"
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var _ = []rune(ss)
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var _ = []byte(ss)
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// implicit is still not
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var _ []rune = ss // ERROR "cannot use|incompatible|invalid"
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var _ []byte = ss // ERROR "cannot use|incompatible|invalid"
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// named slice is now ok
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type Trune []rune
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type Tbyte []byte
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var _ = Trune("abc") // ok
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var _ = Tbyte("abc") // ok
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// implicit is still not
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var _ Trune = "abc" // ERROR "cannot use|incompatible|invalid"
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var _ Tbyte = "abc" // ERROR "cannot use|incompatible|invalid"
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