9b3f9d9444
Slice patterns are different from the rest in that a single slice pattern does not have a distinct constructor if it contains a variable-length subslice pattern. For example, the pattern [a, b, ..tail] can match a slice of length 2, 3, 4 and so on. As a result, the decision tree for exhaustiveness and redundancy analysis should explore each of those constructors separately to determine if the pattern could be useful when specialized for any of them.
30 lines
1.2 KiB
Rust
30 lines
1.2 KiB
Rust
// Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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enum t { a(u), b }
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enum u { c, d }
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fn match_nested_vecs<'a, T>(l1: Option<&'a [T]>, l2: Result<&'a [T], ()>) -> &'static str {
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match (l1, l2) { //~ ERROR non-exhaustive patterns: `(Some([]), Err(_))` not covered
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(Some([]), Ok([])) => "Some(empty), Ok(empty)",
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(Some([_, ..]), Ok(_)) | (Some([_, ..]), Err(())) => "Some(non-empty), any",
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(None, Ok([])) | (None, Err(())) | (None, Ok([_])) => "None, Ok(less than one element)",
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(None, Ok([_, _, ..])) => "None, Ok(at least two elements)"
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}
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}
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fn main() {
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let x = a(c);
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match x { //~ ERROR non-exhaustive patterns: `a(c)` not covered
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a(d) => { fail!("hello"); }
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b => { fail!("goodbye"); }
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}
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}
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