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09ada1af8f
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>
16 lines
345 B
Go
16 lines
345 B
Go
// errorcheck
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// Copyright 2018 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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func _(x int) {
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_ = ~x // unary ~ permitted but the type-checker will complain
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}
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func _(x int) {
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_ = x ~ x // ERROR "unexpected ~ at end of statement"
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}
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