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go/test/fixedbugs/issue48471.go
Dan Scales 902dc38212 go/types, types2: tweak missingMethodReason logic to improve message
This makes the error case pointed out in the issue like the current
message in Go 1.17 or -G=0 mode. The priority is to point out the
similar but wrong method name, rather than a difference in type.

Made changes to both cmd/compile/internal/types2 and go/types.
Added in a missing tab in an error message in go/types.

At the same time, removed the extra "at info" on the have lines (and
pointer receiver lines) of error messages, as requested in #50907.

Fixes #50816
Fixes #50907

Change-Id: I04f8151955bdb6192246cbcb59adc1c4b8a2c4e5
Reviewed-on: https://go-review.googlesource.com/c/go/+/381774
Reviewed-by: Robert Griesemer <gri@golang.org>
Trust: Dan Scales <danscales@google.com>
Run-TryBot: Dan Scales <danscales@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
2022-02-01 16:52:46 +00:00

57 lines
2.2 KiB
Go

// errorcheck -G=3
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package p
type I interface{ M(int) }
type T struct{}
type T2 struct{}
func (*T2) m(int)
type T3 struct{}
func (*T3) M(string) {}
type T4 struct{}
func (*T4) M(int)
type T5 struct{}
func (T5) m(int) {}
type T6 struct{}
func (T6) m(int) string { return "" }
func f(I)
func g() {
f(new(T)) // ERROR "cannot use new\(T\) \(.*type \*T\) as type I in argument to f:\n\t\*T does not implement I \(missing M method\)"
var i I
i = new(T) // ERROR "cannot use new\(T\) \(.*type \*T\) as type I in assignment:\n\t\*T does not implement I \(missing M method\)"
i = I(new(T)) // ERROR "cannot convert new\(T\) \(.*type \*T\) to type I:\n\t\*T does not implement I \(missing M method\)"
i = new(T2) // ERROR "cannot use new\(T2\) \(.*type \*T2\) as type I in assignment:\n\t\*T2 does not implement I \(missing M method\)\n\t\thave m\(int\)\n\t\twant M\(int\)"
i = new(T3) // ERROR "cannot use new\(T3\) \(.*type \*T3\) as type I in assignment:\n\t\*T3 does not implement I \(wrong type for M method\)\n\t\thave M\(string\)\n\t\twant M\(int\)"
i = T4{} // ERROR "cannot use T4\{\} \(.*type T4\) as type I in assignment:\n\tT4 does not implement I \(M method has pointer receiver\)"
i = new(I) // ERROR "cannot use new\(I\) \(.*type \*I\) as type I in assignment:\n\t\*I does not implement I \(type \*I is pointer to interface, not interface\)"
_ = i.(*T2) // ERROR "impossible type assertion: i.\(\*T2\)\n\t\*T2 does not implement I \(missing M method\)\n\t\thave m\(int\)\n\t\twant M\(int\)"
_ = i.(*T3) // ERROR "impossible type assertion: i.\(\*T3\)\n\t\*T3 does not implement I \(wrong type for M method\)\n\t\thave M\(string\)\n\t\twant M\(int\)"
_ = i.(T5) // ERROR ""impossible type assertion: i.\(T5\)\n\tT5 does not implement I \(missing M method\)\n\t\thave m\(int\)\n\t\twant M\(int\)"
_ = i.(T6) // ERROR "impossible type assertion: i.\(T6\)\n\tT6 does not implement I \(missing M method\)\n\t\thave m\(int\) string\n\t\twant M\(int\)"
var t *T4
t = i // ERROR "cannot use i \(variable of type I\) as type \*T4 in assignment:\n\tneed type assertion"
_ = i
}