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https://github.com/golang/go
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581526ce96
This CL detangles the hairy mess that was convlit+defaultlit. In particular, it makes the following changes: 1. convlit1 now follows the standard typecheck behavior of setting "n.Type = nil" if there's an error. Notably, this means for a lot of test cases, we now avoid reporting useless follow-on error messages. For example, after reporting that "1 << s + 1.0" has an invalid shift, we no longer also report that it can't be assigned to string. 2. Previously, assignconvfn had some extra logic for trying to suppress errors from convlit/defaultlit so that it could provide its own errors with better context information. Instead, this extra context information is now passed down into convlit1 directly. 3. Relatedly, this CL also removes redundant calls to defaultlit prior to assignconv. As a consequence, when an expression doesn't make sense for a particular assignment (e.g., assigning an untyped string to an integer), the error messages now say "untyped string" instead of just "string". This is more consistent with go/types behavior. 4. defaultlit2 is now smarter about only trying to convert pairs of untyped constants when it's likely to succeed. This allows us to report better error messages for things like 3+"x"; instead of "cannot convert 3 to string" we now report "mismatched types untyped number and untyped string". Passes toolstash-check. Change-Id: I26822a02dc35855bd0ac774907b1cf5737e91882 Reviewed-on: https://go-review.googlesource.com/c/go/+/187657 Run-TryBot: Matthew Dempsky <mdempsky@google.com> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Robert Griesemer <gri@golang.org>
75 lines
2.2 KiB
Go
75 lines
2.2 KiB
Go
// errorcheck
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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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// Verify that illegal assignments with both explicit and implicit conversions of literals are detected.
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// Does not compile.
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package main
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import "unsafe"
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// explicit conversion of constants
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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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// unsafe.Pointer can only convert to/from uintptr
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var _ = string(unsafe.Pointer(uintptr(65))) // ERROR "convert"
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var _ = float64(unsafe.Pointer(uintptr(65))) // ERROR "convert"
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var _ = int(unsafe.Pointer(uintptr(65))) // ERROR "convert"
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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|cannot"
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var bad3 = s + 'a' // ERROR "conver|incompatible|invalid|cannot"
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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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