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@ -19,7 +19,10 @@ Note that the default features have been disabled. This is a critical step -
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disabled.**
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disabled.**
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Alternatively, we can use the unstable `rustc_private` private feature together
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Alternatively, we can use the unstable `rustc_private` private feature together
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with an `extern crate libc;` declaration as shown in the examples below.
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with an `extern crate libc;` declaration as shown in the examples below. Note that
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windows-msvc targets do not require a libc, and correspondingly there is no `libc`
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crate in their sysroot. We do not need the `extern crate libc;` below, and having it
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on a windows-msvc target would be a compile error.
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## Writing an executable without `std`
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## Writing an executable without `std`
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@ -39,11 +42,12 @@ in the same format as C (aside from the exact integer types being used):
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#![allow(internal_features)]
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#![allow(internal_features)]
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#![no_std]
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#![no_std]
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// Necessary for `panic = "unwind"` builds on some platforms.
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// Necessary for `panic = "unwind"` builds on cfg(unix) platforms.
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#![feature(panic_unwind)]
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#![feature(panic_unwind)]
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extern crate unwind;
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extern crate unwind;
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// Pull in the system libc library for what crt0.o likely requires.
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// Pull in the system libc library for what crt0.o likely requires.
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#[cfg(not(windows))]
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extern crate libc;
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extern crate libc;
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use core::panic::PanicInfo;
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use core::panic::PanicInfo;
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@ -73,11 +77,12 @@ compiler's name mangling too:
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#![no_std]
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#![no_std]
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#![no_main]
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#![no_main]
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// Necessary for `panic = "unwind"` builds on some platforms.
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// Necessary for `panic = "unwind"` builds on cfg(unix) platforms.
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#![feature(panic_unwind)]
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#![feature(panic_unwind)]
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extern crate unwind;
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extern crate unwind;
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// Pull in the system libc library for what crt0.o likely requires.
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// Pull in the system libc library for what crt0.o likely requires.
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#[cfg(not(windows))]
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extern crate libc;
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extern crate libc;
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use core::ffi::{c_char, c_int};
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use core::ffi::{c_char, c_int};
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