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go/test/fixedbugs/issue23587.go

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cmd/compile/internal/syntax: don't assume (operator) ~ means operator ^ The scanner assumed that ~ really meant ^, which may be helpful when coming from C. But ~ is not a valid Go token, and pretending that it should be ^ can lead to confusing error messages. Better to be upfront about it and complain about the invalid character in the first place. This was code "inherited" from the original yacc parser which was derived from a C compiler. It's 10 years later and we can probably assume that people are less confused about C and Go. Fixes #23587. Change-Id: I8d8f9b55b0dff009b75c1530d729bf9092c5aea6 Reviewed-on: https://go-review.googlesource.com/94160 Reviewed-by: Matthew Dempsky <mdempsky@google.com>
2018-02-14 21:54:28 -07:00
// errorcheck
// Copyright 2018 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
cmd/compile/internal/syntax: add "~" operator Change-Id: I7991103d97b97260d9615b7f5baf7ec75ad87d1f Reviewed-on: https://go-review.googlesource.com/c/go/+/307370 Trust: Robert Griesemer <gri@golang.org> Reviewed-by: Robert Findley <rfindley@google.com>
2021-04-05 17:52:25 -06:00
func _(x int) {
cmd/compile/internal/syntax: parser to accept ~x as unary expression Accept ~x as ordinary unary expression in the parser but recognize such expressions as invalid in the type checker. This change opens the door to recognizing complex type constraint literals such as `*E|~int` in `[P *E|~int]` and parse them correctly instead of reporting a parse error because `P*E|~int` syntactically looks like an incorrect array length expression (binary expression where the RHS of | is an invalid unary expression ~int). As a result, the parser is more forgiving with expressions but the type checker will reject invalid uses as before. We could pass extra information into the binary/unary expression parse functions to prevent the use of ~ in invalid situations but it doesn't seem worth the trouble. In fact it may be advantageous to allow a more liberal expression syntax especially in the presence of errors (better parser synchronization after an error). Preparation for fixing #49482. Change-Id: I119e8bd9445dfa6460fcd7e0658e3554a34b2769 Reviewed-on: https://go-review.googlesource.com/c/go/+/402255 Run-TryBot: Robert Griesemer <gri@golang.org> TryBot-Result: Gopher Robot <gobot@golang.org> Reviewed-by: Ian Lance Taylor <iant@google.com> Reviewed-by: Robert Griesemer <gri@google.com> Auto-Submit: Robert Griesemer <gri@google.com>
2022-04-25 17:26:10 -06:00
_ = ~x // unary ~ permitted but the type-checker will complain
cmd/compile/internal/syntax: add "~" operator Change-Id: I7991103d97b97260d9615b7f5baf7ec75ad87d1f Reviewed-on: https://go-review.googlesource.com/c/go/+/307370 Trust: Robert Griesemer <gri@golang.org> Reviewed-by: Robert Findley <rfindley@google.com>
2021-04-05 17:52:25 -06:00
}
func _(x int) {
_ = x ~ x // ERROR "unexpected ~ at end of statement"
cmd/compile/internal/syntax: don't assume (operator) ~ means operator ^ The scanner assumed that ~ really meant ^, which may be helpful when coming from C. But ~ is not a valid Go token, and pretending that it should be ^ can lead to confusing error messages. Better to be upfront about it and complain about the invalid character in the first place. This was code "inherited" from the original yacc parser which was derived from a C compiler. It's 10 years later and we can probably assume that people are less confused about C and Go. Fixes #23587. Change-Id: I8d8f9b55b0dff009b75c1530d729bf9092c5aea6 Reviewed-on: https://go-review.googlesource.com/94160 Reviewed-by: Matthew Dempsky <mdempsky@google.com>
2018-02-14 21:54:28 -07:00
}
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