58 lines
1.6 KiB
Rust
58 lines
1.6 KiB
Rust
// Copyright 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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// Test that an `&mut self` method, when invoked on an lvalue whose
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// type is `&mut [u8]`, passes in a pointer to the lvalue and not a
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// temporary. Issue #19147.
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#![feature(core, old_io)]
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use std::mem;
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use std::slice;
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pub type IoResult<T> = Result<T, ()>;
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trait MyWriter {
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fn my_write(&mut self, buf: &[u8]) -> IoResult<()>;
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}
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impl<'a> MyWriter for &'a mut [u8] {
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fn my_write(&mut self, buf: &[u8]) -> IoResult<()> {
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slice::bytes::copy_memory(buf, *self);
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let write_len = buf.len();
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unsafe {
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*self = slice::from_raw_parts_mut(
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self.as_mut_ptr().offset(write_len as isize),
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self.len() - write_len
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);
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}
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Ok(())
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}
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}
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fn main() {
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let mut buf = [0; 6];
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{
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let mut writer: &mut [_] = &mut buf;
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writer.my_write(&[0, 1, 2]).unwrap();
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writer.my_write(&[3, 4, 5]).unwrap();
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}
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// If `my_write` is not modifying `buf` in place, then we will
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// wind up with `[3, 4, 5, 0, 0, 0]` because the first call to
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// `my_write()` doesn't update the starting point for the write.
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assert_eq!(buf, [0, 1, 2, 3, 4, 5]);
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}
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