3e626375d8
[breaking-change]
1. The internal layout for traits has changed from (vtable, data) to (data, vtable). If you were relying on this in unsafe transmutes, you might get some very weird and apparently unrelated errors. You should not be doing this! Prefer not to do this at all, but if you must, you should use raw::TraitObject rather than hardcoding rustc's internal representation into your code.
2. The minimal type of reference-to-vec-literals (e.g., `&[1, 2, 3]`) is now a fixed size vec (e.g., `&[int, ..3]`) where it used to be an unsized vec (e.g., `&[int]`). If you want the unszied type, you must explicitly give the type (e.g., `let x: &[_] = &[1, 2, 3]`). Note in particular where multiple blocks must have the same type (e.g., if and else clauses, vec elements), the compiler will not coerce to the unsized type without a hint. E.g., `[&[1], &[1, 2]]` used to be a valid expression of type '[&[int]]'. It no longer type checks since the first element now has type `&[int, ..1]` and the second has type &[int, ..2]` which are incompatible.
3. The type of blocks (including functions) must be coercible to the expected type (used to be a subtype). Mostly this makes things more flexible and not less (in particular, in the case of coercing function bodies to the return type). However, in some rare cases, this is less flexible. TBH, I'm not exactly sure of the exact effects. I think the change causes us to resolve inferred type variables slightly earlier which might make us slightly more restrictive. Possibly it only affects blocks with unreachable code. E.g., `if ... { fail!(); "Hello" }` used to type check, it no longer does. The fix is to add a semicolon after the string.
116 lines
4.0 KiB
Rust
116 lines
4.0 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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extern crate debug;
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fn reflect() {
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// Tests for reflective printing.
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// Also tests drop glue.
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let x = [1, 2, 3, 4];
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let x2 = [(), (), ()];
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let e1: [uint, ..0] = [];
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let e2: [&'static str, ..0] = [];
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let e3: [(), ..0] = [];
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assert!(format!("{:?}", x) == "[1u, 2u, 3u, 4u]".to_string());
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assert!(format!("{:?}", x2) == "[(), (), ()]".to_string());
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assert!(format!("{:?}", e1) == "[]".to_string());
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assert!(format!("{:?}", e2) == "[]".to_string());
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assert!(format!("{:?}", e3) == "[]".to_string());
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let rx: &[uint, ..4] = &x;
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let rx2: &[(), ..3] = &x2;
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let re1: &[uint, ..0] = &e1;
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let re2: &[&'static str, ..0] = &e2;
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let re3: &[(), ..0] = &e3;
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assert!(format!("{:?}", rx) == "&[1u, 2u, 3u, 4u]".to_string());
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assert!(format!("{:?}", rx2) == "&[(), (), ()]".to_string());
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assert!(format!("{:?}", re1) == "&[]".to_string());
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assert!(format!("{:?}", re2) == "&[]".to_string());
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assert!(format!("{:?}", re3) == "&[]".to_string());
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let rx: &[uint] = &x;
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let rx2: &[()] = &x2;
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let re1: &[uint] = &e1;
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let re2: &[&'static str] = &e2;
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let re3: &[()] = &e3;
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assert!(format!("{:?}", rx) == "&[1u, 2u, 3u, 4u]".to_string());
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assert!(format!("{:?}", rx2) == "&[(), (), ()]".to_string());
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assert!(format!("{:?}", re1) == "&[]".to_string());
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assert!(format!("{:?}", re2) == "&[]".to_string());
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assert!(format!("{:?}", re3) == "&[]".to_string());
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// FIXME(15049) These should all work some day.
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/*let rx: Box<[uint, ..4]> = box x;
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let rx2: Box<[(), ..3]> = box x2;
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let re1: Box<[uint, ..0]> = box e1;
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let re2: Box<[&'static str, ..0]> = box e2;
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let re3: Box<[(), ..0]> = box e3;
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assert!(format!("{:?}", rx) == "box [1u, 2u, 3u, 4u]".to_string());
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assert!(format!("{:?}", rx2) == "box [(), (), ()]".to_string());
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assert!(format!("{:?}", re1) == "box []".to_string());
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assert!(format!("{:?}", re2) == "box []".to_string());
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assert!(format!("{:?}", re3) == "box []".to_string());
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let x = [1, 2, 3, 4];
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let x2 = [(), (), ()];
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let e1: [uint, ..0] = [];
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let e2: [&'static str, ..0] = [];
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let e3: [(), ..0] = [];
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let rx: Box<[uint]> = box x;
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let rx2: Box<[()]> = box x2;
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let re1: Box<[uint]> = box e1;
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let re2: Box<[&'static str]> = box e2;
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let re3: Box<[()]> = box e3;
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assert!(format!("{:?}", rx) == "box [1u, 2u, 3u, 4u]".to_string());
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assert!(format!("{:?}", rx2) == "box [(), (), ()]".to_string());
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assert!(format!("{:?}", re1) == "box []".to_string());
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assert!(format!("{:?}", re2) == "box []".to_string());
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assert!(format!("{:?}", re3) == "box []".to_string());*/
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}
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fn sub_expr() {
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// Test for a &[T] => &&[T] coercion in sub-expression position
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// (surpisingly, this can cause errors which are not caused by either of:
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// `let x = vec.mut_slice(0, 2);`
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// `foo(vec.mut_slice(0, 2));` ).
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let mut vec: Vec<int> = vec!(1, 2, 3, 4);
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let b: &mut [int] = [1, 2];
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assert!(vec.mut_slice(0, 2) == b);
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}
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fn index() {
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// Tests for indexing into box/& [T, ..n]
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let x: [int, ..3] = [1, 2, 3];
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let mut x: Box<[int, ..3]> = box x;
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assert!(x[0] == 1);
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assert!(x[1] == 2);
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assert!(x[2] == 3);
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x[1] = 45;
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assert!(x[0] == 1);
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assert!(x[1] == 45);
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assert!(x[2] == 3);
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let mut x: [int, ..3] = [1, 2, 3];
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let x: &mut [int, ..3] = &mut x;
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assert!(x[0] == 1);
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assert!(x[1] == 2);
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assert!(x[2] == 3);
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x[1] = 45;
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assert!(x[0] == 1);
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assert!(x[1] == 45);
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assert!(x[2] == 3);
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}
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pub fn main() {
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reflect();
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sub_expr();
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index();
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}
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