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Diffstat (limited to 'doc/tutorial-ffi.md')
| -rw-r--r-- | doc/tutorial-ffi.md | 23 |
1 files changed, 20 insertions, 3 deletions
diff --git a/doc/tutorial-ffi.md b/doc/tutorial-ffi.md index 57dc926dfa9..7d975d0ef62 100644 --- a/doc/tutorial-ffi.md +++ b/doc/tutorial-ffi.md @@ -418,15 +418,32 @@ calling foreign functions. Some foreign functions, most notably the Windows API, conventions. Rust provides a way to tell the compiler which convention to use: ~~~~ -#[cfg(target_os = "win32")] +#[cfg(target_os = "win32", target_arch = "x86")] #[link_name = "kernel32"] extern "stdcall" { fn SetEnvironmentVariableA(n: *u8, v: *u8) -> int; } ~~~~ -This applies to the entire `extern` block, and must be either `"cdecl"` or -`"stdcall"`. The compiler may eventually support other calling conventions. +This applies to the entire `extern` block. The list of supported ABI constraints +are: + +* `stdcall` +* `aapcs` +* `cdecl` +* `fastcall` +* `Rust` +* `rust-intrinsic` +* `system` +* `C` + +Most of the abis in this list are self-explanatory, but the `system` abi may +seem a little odd. This constraint selects whatever the appropriate ABI is for +interoperating with the target's libraries. For example, on win32 with a x86 +architecture, this means that the abi used would be `stdcall`. On x86_64, +however, windows uses the `C` calling convention, so `C` would be used. This +means that in our previous example, we could have used `extern "system" { ... }` +to define a block for all windows systems, not just x86 ones. # Interoperability with foreign code |