mirror of
https://github.com/golang/go
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396b6c2e7c
The assignment type-checking code previously bounced around a lot between the LHS and RHS sides of the assignment. But there's actually a very simple, consistent pattern to how to type check assignments: 1. Check the RHS expression. 2. If the LHS expression is an identifier that was declared in this statement and it doesn't have an explicit type, give it the RHS expression's default type. 3. Check the LHS expression. 4. Try assigning the RHS expression to the LHS expression, adding implicit conversions as needed. This CL implements this algorithm, and refactors tcAssign and tcAssignList to use a common implementation. It also fixes the error messages to consistently say just "1 variable" or "1 value", rather than occasionally "1 variables" or "1 values". Fixes #43348. Passes toolstash -cmp. Change-Id: I749cb8d6ccbc7d22cd7cb0a381f58a39fc2696b5 Reviewed-on: https://go-review.googlesource.com/c/go/+/280112 Trust: Matthew Dempsky <mdempsky@google.com> Run-TryBot: Matthew Dempsky <mdempsky@google.com> TryBot-Result: Go Bot <gobot@golang.org> Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
145 lines
6.5 KiB
Go
145 lines
6.5 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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package p
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import "unsafe"
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const C = 1
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var x, x1, x2 int
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var b bool
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var s string
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var c chan int
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var cp complex128
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var slice []int
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var array [2]int
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var bytes []byte
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var runes []rune
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var r rune
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func f0() {}
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func f1() int { return 1 }
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func f2() (int, int) { return 1, 1 }
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type T struct{ X int }
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func (T) M1() int { return 1 }
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func (T) M0() {}
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func (T) M() {}
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var t T
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var tp *T
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type I interface{ M() }
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var i I
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var m map[int]int
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func _() {
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// Note: if the next line changes to x, the error silences the x+x etc below!
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x1 // ERROR "x1 evaluated but not used"
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nil // ERROR "nil evaluated but not used"
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C // ERROR "C evaluated but not used"
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1 // ERROR "1 evaluated but not used"
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x + x // ERROR "x \+ x evaluated but not used"
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x - x // ERROR "x - x evaluated but not used"
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x | x // ERROR "x \| x evaluated but not used"
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"a" + s // ERROR ".a. \+ s evaluated but not used"
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&x // ERROR "&x evaluated but not used"
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b && b // ERROR "b && b evaluated but not used"
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append(slice, 1) // ERROR "append\(slice, 1\) evaluated but not used"
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string(bytes) // ERROR "string\(bytes\) evaluated but not used"
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string(runes) // ERROR "string\(runes\) evaluated but not used"
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f0() // ok
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f1() // ok
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f2() // ok
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_ = f0() // ERROR "f0\(\) used as value"
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_ = f1() // ok
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_, _ = f2() // ok
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_ = f2() // ERROR "assignment mismatch: 1 variable but f2 returns 2 values"
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_ = f1(), 0 // ERROR "assignment mismatch: 1 variable but 2 values"
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T.M0 // ERROR "T.M0 evaluated but not used"
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t.M0 // ERROR "t.M0 evaluated but not used"
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cap // ERROR "use of builtin cap not in function call"
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cap(slice) // ERROR "cap\(slice\) evaluated but not used"
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close(c) // ok
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_ = close(c) // ERROR "close\(c\) used as value"
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func() {} // ERROR "func literal evaluated but not used"
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X{} // ERROR "undefined: X"
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map[string]int{} // ERROR "map\[string\]int{} evaluated but not used"
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struct{}{} // ERROR "struct ?{}{} evaluated but not used"
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[1]int{} // ERROR "\[1\]int{} evaluated but not used"
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[]int{} // ERROR "\[\]int{} evaluated but not used"
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&struct{}{} // ERROR "&struct ?{}{} evaluated but not used"
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float32(x) // ERROR "float32\(x\) evaluated but not used"
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I(t) // ERROR "I\(t\) evaluated but not used"
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int(x) // ERROR "int\(x\) evaluated but not used"
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copy(slice, slice) // ok
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_ = copy(slice, slice) // ok
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delete(m, 1) // ok
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_ = delete(m, 1) // ERROR "delete\(m, 1\) used as value"
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t.X // ERROR "t.X evaluated but not used"
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tp.X // ERROR "tp.X evaluated but not used"
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t.M // ERROR "t.M evaluated but not used"
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I.M // ERROR "I.M evaluated but not used"
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i.(T) // ERROR "i.\(T\) evaluated but not used"
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x == x // ERROR "x == x evaluated but not used"
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x != x // ERROR "x != x evaluated but not used"
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x != x // ERROR "x != x evaluated but not used"
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x < x // ERROR "x < x evaluated but not used"
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x >= x // ERROR "x >= x evaluated but not used"
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x > x // ERROR "x > x evaluated but not used"
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*tp // ERROR "\*tp evaluated but not used"
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slice[0] // ERROR "slice\[0\] evaluated but not used"
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m[1] // ERROR "m\[1\] evaluated but not used"
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len(slice) // ERROR "len\(slice\) evaluated but not used"
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make(chan int) // ERROR "make\(chan int\) evaluated but not used"
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make(map[int]int) // ERROR "make\(map\[int\]int\) evaluated but not used"
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make([]int, 1) // ERROR "make\(\[\]int, 1\) evaluated but not used"
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x * x // ERROR "x \* x evaluated but not used"
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x / x // ERROR "x / x evaluated but not used"
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x % x // ERROR "x % x evaluated but not used"
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x << x // ERROR "x << x evaluated but not used"
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x >> x // ERROR "x >> x evaluated but not used"
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x & x // ERROR "x & x evaluated but not used"
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x &^ x // ERROR "x &\^ x evaluated but not used"
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new(int) // ERROR "new\(int\) evaluated but not used"
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!b // ERROR "!b evaluated but not used"
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^x // ERROR "\^x evaluated but not used"
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+x // ERROR "\+x evaluated but not used"
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-x // ERROR "-x evaluated but not used"
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b || b // ERROR "b \|\| b evaluated but not used"
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panic(1) // ok
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_ = panic(1) // ERROR "panic\(1\) used as value"
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print(1) // ok
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_ = print(1) // ERROR "print\(1\) used as value"
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println(1) // ok
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_ = println(1) // ERROR "println\(1\) used as value"
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c <- 1 // ok
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slice[1:1] // ERROR "slice\[1:1\] evaluated but not used"
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array[1:1] // ERROR "array\[1:1\] evaluated but not used"
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s[1:1] // ERROR "s\[1:1\] evaluated but not used"
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slice[1:1:1] // ERROR "slice\[1:1:1\] evaluated but not used"
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array[1:1:1] // ERROR "array\[1:1:1\] evaluated but not used"
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recover() // ok
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<-c // ok
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string(r) // ERROR "string\(r\) evaluated but not used"
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iota // ERROR "undefined: iota"
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real(cp) // ERROR "real\(cp\) evaluated but not used"
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imag(cp) // ERROR "imag\(cp\) evaluated but not used"
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complex(1, 2) // ERROR "complex\(1, 2\) evaluated but not used"
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unsafe.Alignof(t.X) // ERROR "unsafe.Alignof\(t.X\) evaluated but not used"
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unsafe.Offsetof(t.X) // ERROR "unsafe.Offsetof\(t.X\) evaluated but not used"
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unsafe.Sizeof(t) // ERROR "unsafe.Sizeof\(t\) evaluated but not used"
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_ = int // ERROR "type int is not an expression"
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(x) // ERROR "x evaluated but not used"
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_ = new(x2) // ERROR "x2 is not a type"
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_ = new(1 + 1) // ERROR "1 \+ 1 is not a type"
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}
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