Source file test/convlit.go
1 // errorcheck 2 3 // Copyright 2009 The Go Authors. All rights reserved. 4 // Use of this source code is governed by a BSD-style 5 // license that can be found in the LICENSE file. 6 7 // Verify that illegal assignments with both explicit and implicit conversions of literals are detected. 8 // Does not compile. 9 10 package main 11 12 import "unsafe" 13 14 // explicit conversion of constants 15 var x1 = string(1) 16 var x2 string = string(1) 17 var x3 = int(1.5) // ERROR "convert|truncate" 18 var x4 int = int(1.5) // ERROR "convert|truncate" 19 var x5 = "a" + string(1) 20 var x6 = int(1e100) // ERROR "overflow|cannot convert" 21 var x7 = float32(1e1000) // ERROR "overflow|cannot convert" 22 23 // unsafe.Pointer can only convert to/from uintptr 24 var _ = string(unsafe.Pointer(uintptr(65))) // ERROR "convert|conversion" 25 var _ = float64(unsafe.Pointer(uintptr(65))) // ERROR "convert|conversion" 26 var _ = int(unsafe.Pointer(uintptr(65))) // ERROR "convert|conversion" 27 28 // implicit conversions merit scrutiny 29 var s string 30 var bad1 string = 1 // ERROR "conver|incompatible|invalid|cannot" 31 var bad2 = s + 1 // ERROR "conver|incompatible|invalid|cannot" 32 var bad3 = s + 'a' // ERROR "conver|incompatible|invalid|cannot" 33 var bad4 = "a" + 1 // ERROR "literals|incompatible|convert|invalid" 34 var bad5 = "a" + 'a' // ERROR "literals|incompatible|convert|invalid" 35 36 var bad6 int = 1.5 // ERROR "convert|truncate" 37 var bad7 int = 1e100 // ERROR "overflow|truncated to int|truncated" 38 var bad8 float32 = 1e200 // ERROR "overflow" 39 40 // but these implicit conversions are okay 41 var good1 string = "a" 42 var good2 int = 1.0 43 var good3 int = 1e9 44 var good4 float64 = 1e20 45 46 // explicit conversion of string is okay 47 var _ = []rune("abc") 48 var _ = []byte("abc") 49 50 // implicit is not 51 var _ []int = "abc" // ERROR "cannot use|incompatible|invalid|cannot convert" 52 var _ []byte = "abc" // ERROR "cannot use|incompatible|invalid|cannot convert" 53 54 // named string is okay 55 type Tstring string 56 57 var ss Tstring = "abc" 58 var _ = []rune(ss) 59 var _ = []byte(ss) 60 61 // implicit is still not 62 var _ []rune = ss // ERROR "cannot use|incompatible|invalid" 63 var _ []byte = ss // ERROR "cannot use|incompatible|invalid" 64 65 // named slice is now ok 66 type Trune []rune 67 type Tbyte []byte 68 69 var _ = Trune("abc") // ok 70 var _ = Tbyte("abc") // ok 71 72 // implicit is still not 73 var _ Trune = "abc" // ERROR "cannot use|incompatible|invalid|cannot convert" 74 var _ Tbyte = "abc" // ERROR "cannot use|incompatible|invalid|cannot convert" 75