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Add doc link for eh_personality language item

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Philipp Oppermann
2020-01-29 13:29:01 +01:00
parent 571c66c1b2
commit 409c6de44a
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blog/content/second-edition/posts/01-freestanding-rust-binary/index.md
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@@ -147,8 +147,9 @@ Language items are special functions and types that are required internally by t
While providing custom implementations of language items is possible, it should only be done as a last resort. The reason is that language items are highly unstable implementation details and not even type checked (so the compiler doesn't even check if a function has the right argument types). Fortunately, there is a more stable way to fix the above language item error. While providing custom implementations of language items is possible, it should only be done as a last resort. The reason is that language items are highly unstable implementation details and not even type checked (so the compiler doesn't even check if a function has the right argument types). Fortunately, there is a more stable way to fix the above language item error.
The `eh_personality` language item marks a function that is used for implementing [stack unwinding]. By default, Rust uses unwinding to run the destructors of all live stack variables in case of a [panic]. This ensures that all used memory is freed and allows the parent thread to catch the panic and continue execution. Unwinding, however, is a complicated process and requires some OS specific libraries (e.g. [libunwind] on Linux or [structured exception handling] on Windows), so we don't want to use it for our operating system. The [`eh_personality` language item] marks a function that is used for implementing [stack unwinding]. By default, Rust uses unwinding to run the destructors of all live stack variables in case of a [panic]. This ensures that all used memory is freed and allows the parent thread to catch the panic and continue execution. Unwinding, however, is a complicated process and requires some OS specific libraries (e.g. [libunwind] on Linux or [structured exception handling] on Windows), so we don't want to use it for our operating system.
[`eh_personality` language item]: https://github.com/rust-lang/rust/blob/edb368491551a77d77a48446d4ee88b35490c565/src/libpanic_unwind/gcc.rs#L11-L45
[stack unwinding]: http://www.bogotobogo.com/cplusplus/stackunwinding.php [stack unwinding]: http://www.bogotobogo.com/cplusplus/stackunwinding.php
[libunwind]: http://www.nongnu.org/libunwind/ [libunwind]: http://www.nongnu.org/libunwind/
[structured exception handling]: https://msdn.microsoft.com/en-us/library/windows/desktop/ms680657(v=vs.85).aspx [structured exception handling]: https://msdn.microsoft.com/en-us/library/windows/desktop/ms680657(v=vs.85).aspx