rust/src/test/compile-fail/packed-struct-generic-transmute.rs

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// Copyright 2013 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
// This assumes the packed and non-packed structs are different sizes.
// the error points to the start of the file, not the line with the
// transmute
// error-pattern: transmute called on types with different size
extern crate debug;
core: Remove the cast module This commit revisits the `cast` module in libcore and libstd, and scrutinizes all functions inside of it. The result was to remove the `cast` module entirely, folding all functionality into the `mem` module. Specifically, this is the fate of each function in the `cast` module. * transmute - This function was moved to `mem`, but it is now marked as #[unstable]. This is due to planned changes to the `transmute` function and how it can be invoked (see the #[unstable] comment). For more information, see RFC 5 and #12898 * transmute_copy - This function was moved to `mem`, with clarification that is is not an error to invoke it with T/U that are different sizes, but rather that it is strongly discouraged. This function is now #[stable] * forget - This function was moved to `mem` and marked #[stable] * bump_box_refcount - This function was removed due to the deprecation of managed boxes as well as its questionable utility. * transmute_mut - This function was previously deprecated, and removed as part of this commit. * transmute_mut_unsafe - This function doesn't serve much of a purpose when it can be achieved with an `as` in safe code, so it was removed. * transmute_lifetime - This function was removed because it is likely a strong indication that code is incorrect in the first place. * transmute_mut_lifetime - This function was removed for the same reasons as `transmute_lifetime` * copy_lifetime - This function was moved to `mem`, but it is marked `#[unstable]` now due to the likelihood of being removed in the future if it is found to not be very useful. * copy_mut_lifetime - This function was also moved to `mem`, but had the same treatment as `copy_lifetime`. * copy_lifetime_vec - This function was removed because it is not used today, and its existence is not necessary with DST (copy_lifetime will suffice). In summary, the cast module was stripped down to these functions, and then the functions were moved to the `mem` module. transmute - #[unstable] transmute_copy - #[stable] forget - #[stable] copy_lifetime - #[unstable] copy_mut_lifetime - #[unstable] [breaking-change]
2014-05-09 12:34:51 -05:00
use std::mem;
#[repr(packed)]
struct Foo<T,S> {
bar: T,
baz: S
}
struct Oof<T, S> {
rab: T,
zab: S
}
fn main() {
let foo = Foo { bar: [1u8, 2, 3, 4, 5], baz: 10i32 };
unsafe {
core: Remove the cast module This commit revisits the `cast` module in libcore and libstd, and scrutinizes all functions inside of it. The result was to remove the `cast` module entirely, folding all functionality into the `mem` module. Specifically, this is the fate of each function in the `cast` module. * transmute - This function was moved to `mem`, but it is now marked as #[unstable]. This is due to planned changes to the `transmute` function and how it can be invoked (see the #[unstable] comment). For more information, see RFC 5 and #12898 * transmute_copy - This function was moved to `mem`, with clarification that is is not an error to invoke it with T/U that are different sizes, but rather that it is strongly discouraged. This function is now #[stable] * forget - This function was moved to `mem` and marked #[stable] * bump_box_refcount - This function was removed due to the deprecation of managed boxes as well as its questionable utility. * transmute_mut - This function was previously deprecated, and removed as part of this commit. * transmute_mut_unsafe - This function doesn't serve much of a purpose when it can be achieved with an `as` in safe code, so it was removed. * transmute_lifetime - This function was removed because it is likely a strong indication that code is incorrect in the first place. * transmute_mut_lifetime - This function was removed for the same reasons as `transmute_lifetime` * copy_lifetime - This function was moved to `mem`, but it is marked `#[unstable]` now due to the likelihood of being removed in the future if it is found to not be very useful. * copy_mut_lifetime - This function was also moved to `mem`, but had the same treatment as `copy_lifetime`. * copy_lifetime_vec - This function was removed because it is not used today, and its existence is not necessary with DST (copy_lifetime will suffice). In summary, the cast module was stripped down to these functions, and then the functions were moved to the `mem` module. transmute - #[unstable] transmute_copy - #[stable] forget - #[stable] copy_lifetime - #[unstable] copy_mut_lifetime - #[unstable] [breaking-change]
2014-05-09 12:34:51 -05:00
let oof: Oof<[u8, .. 5], i32> = mem::transmute(foo);
log: Introduce liblog, the old std::logging This commit moves all logging out of the standard library into an external crate. This crate is the new crate which is responsible for all logging macros and logging implementation. A few reasons for this change are: * The crate map has always been a bit of a code smell among rust programs. It has difficulty being loaded on almost all platforms, and it's used almost exclusively for logging and only logging. Removing the crate map is one of the end goals of this movement. * The compiler has a fair bit of special support for logging. It has the __log_level() expression as well as generating a global word per module specifying the log level. This is unfairly favoring the built-in logging system, and is much better done purely in libraries instead of the compiler itself. * Initialization of logging is much easier to do if there is no reliance on a magical crate map being available to set module log levels. * If the logging library can be written outside of the standard library, there's no reason that it shouldn't be. It's likely that we're not going to build the highest quality logging library of all time, so third-party libraries should be able to provide just as high-quality logging systems as the default one provided in the rust distribution. With a migration such as this, the change does not come for free. There are some subtle changes in the behavior of liblog vs the previous logging macros: * The core change of this migration is that there is no longer a physical log-level per module. This concept is still emulated (it is quite useful), but there is now only a global log level, not a local one. This global log level is a reflection of the maximum of all log levels specified. The previously generated logging code looked like: if specified_level <= __module_log_level() { println!(...) } The newly generated code looks like: if specified_level <= ::log::LOG_LEVEL { if ::log::module_enabled(module_path!()) { println!(...) } } Notably, the first layer of checking is still intended to be "super fast" in that it's just a load of a global word and a compare. The second layer of checking is executed to determine if the current module does indeed have logging turned on. This means that if any module has a debug log level turned on, all modules with debug log levels get a little bit slower (they all do more expensive dynamic checks to determine if they're turned on or not). Semantically, this migration brings no change in this respect, but runtime-wise, this will have a perf impact on some code. * A `RUST_LOG=::help` directive will no longer print out a list of all modules that can be logged. This is because the crate map will no longer specify the log levels of all modules, so the list of modules is not known. Additionally, warnings can no longer be provided if a malformed logging directive was supplied. The new "hello world" for logging looks like: #[phase(syntax, link)] extern crate log; fn main() { debug!("Hello, world!"); }
2014-03-09 00:11:44 -06:00
println!("{:?}", oof);
}
}