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Jan 18, 2023
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Copyedits to FFI and unwinding section #396

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Copyedits to FFI and unwinding section
tmandry Jan 14, 2023
d1a59f5
Re-word: only "most" ABIs have `-unwind`
BatmanAoD Jan 17, 2023
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19 changes: 11 additions & 8 deletions src/ffi.md
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Expand Up @@ -722,16 +722,19 @@ No `transmute` required!
## FFI and unwinding

It’s important to be mindful of unwinding when working with FFI. Each
non-`Rust` ABI comes in two variants, one with `-unwind` suffix and one without. If
you expect Rust `panic`s or foreign (e.g. C++) exceptions to cross an FFI
boundary, that boundary must use the appropriate `-unwind` ABI string (note
that compiling with `panic=abort` will still cause `panic!` to immediately
abort the process, regardless of which ABI is specified by the function that
`panic`s).
ABI comes in two variants, one with `-unwind` suffix and one without (except
the `Rust` ABI, which always permits unwinding).

If you expect Rust `panic`s or foreign (e.g. C++) exceptions to cross an FFI
boundary, that boundary must use the appropriate `-unwind` ABI string.
Conversely, if you do not expect unwinding to cross an ABI boundary, use one of
the non-`unwind` ABI strings (other than `Rust`, which always permits
unwinding). If an unwinding operation does encounter an ABI boundary that is
the non-`unwind` ABI strings.

> Note: Compiling with `panic=abort` will still cause `panic!` to immediately
abort the process, regardless of which ABI is specified by the function that
`panic`s.

If an unwinding operation does encounter an ABI boundary that is
not permitted to unwind, the behavior depends on the source of the unwinding
(Rust `panic` or a foreign exception):

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