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Charlie Barto b3ac3efcf9 Replace confusing note in cpp.md on "RVO"
The original commit adding this note referenced #778, but then went on to talk about how the problem was RVO and that the problem is not possible to solve in bindgen because bindgen can't know if RVO happened or not. However this is incorrect in several ways. The problem in #778 has nothing whatsoever to do with RVO but rather with bindgen simply not understanding the calling convention for passing or returning types that are "non trivial for the purposes of calls". This is completely consistent and does not depend on what the optimizer decided to do (after all, if callsite side calling-convention did depend on what the optimizer happened to do inside the function it would be impossible for C++ compilers to emit correct calls to external C++ functions!).

You can see this quite clearly [here](https://godbolt.org/#z:OYLghAFBqd5QCxAYwPYBMCmBRdBLAF1QCcAaPECAMzwBtMA7AQwFtMQByARg9KtQYEAysib0QXACx8BBAKoBnTAAUAHpwAMvAFYTStJg1DIApACYAQuYukl9ZATwDKjdAGFUtAK4sGIM6SuADJ4DJgAcj4ARpjEEgDspAAOqAqETgwe3r7%2ByanpAiFhkSwxcVyJdpgOGUIETMQEWT5%2BAVU1AnUNBEUR0bEJtvWNzTltwz2hfaUDFQCUtqhexMjsHAD06wDUACoAnkmYW3tLxFtoWFsIsZikWyRbtKhM6FuGW5iqrEn0AHQmGgAggoCMQvA4tgRMCCokwlFsTPErPEACImADMViBILBEKhIIRSIBgK2pMh0IIEDmGKxJLJ%2BMpaAYBIZ5gAbNTMcSyVsAG6oPDoABUkJpxMRaK5QIZWwUAEcvA1MFTCbSeTKCIjkZK1WTiJgCMsGKKpYCJeKgaECFsWExQiqtdz6RTIQj0SjZQqlVSxUCnaT9YbiMa0gAvTCoKgQBmc2kSjgLWicACsvD8HC0pFQnDc1msstOqwRZnRPFIBE0CYWAGsQOj0b9603my22fpOJI05Ws5xeAoQBpy5WFnBYEg0CwknRYuRKBOp/Q4sAFMwkgoEKgCKQsLy8KsAGp4TAAdwA8od02WaLQocR%2BxAot2oqEGntOGWJ2xBKeGLQ3xneCwW0jHEADtzwfUal5aFu0%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%2Bzpl5ny/O89sOFTWruxCsLIpiuKEqSlKvDSjKICy0nizygrhxK%2BtGwq8qVZqureAa2wmsKrRipVswgvq3tmo9hZoLvDIQEkIA) Notice how the body of `main` is identical no matter if copy elision is enabled or not. To get `test` passed in a register you must remove the copy constructor.

I spent a few hours being really confused by this note before I tracked down the original PR and realized what it was trying to talk about. Hopefully this saves the next person to come across it the same trouble.

As an aside I suspect the clang c bindings can already give you information on special member functions and base classes, making it fairly easy to do this correctly. AFAICT bindgen already does not rely on llvm's code generation facilities to figure out the ABI of calls for C (except perhaps indirectly, via rustc), so this seems reasonable to just do in bindgen, explicitly.
2022-10-31 11:09:27 +01:00
.github ci: clippy fixes. 2022-10-16 21:29:41 +02:00
bindgen Sanitize RegexSet input so alternation is properly handled (#1756) 2022-10-24 10:39:52 -05:00
bindgen-cli Avoid suppressing panic messages (#2323) 2022-10-24 11:52:46 -05:00
bindgen-integration split the repo into a workspace 2022-10-04 20:47:17 -05:00
bindgen-tests Sanitize RegexSet input so alternation is properly handled (#1756) 2022-10-24 10:39:52 -05:00
book Replace confusing note in cpp.md on "RVO" 2022-10-31 11:09:27 +01:00
ci split the repo into a workspace 2022-10-04 20:47:17 -05:00
csmith-fuzzing Move the csmith-fuzzing directory to the top level. 2022-10-16 21:29:41 +02:00
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appveyor.yml tests: Stop testing libclang 4.0 2022-03-15 03:53:10 +01:00
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CHANGELOG.md Avoid suppressing panic messages (#2323) 2022-10-24 11:52:46 -05:00
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rustfmt.toml Rustfmt. 2019-09-17 11:53:23 +09:00

crates.io docs.rs

bindgen

bindgen automatically generates Rust FFI bindings to C (and some C++) libraries.

For example, given the C header doggo.h:

typedef struct Doggo {
    int many;
    char wow;
} Doggo;

void eleven_out_of_ten_majestic_af(Doggo* pupper);

bindgen produces Rust FFI code allowing you to call into the doggo library's functions and use its types:

/* automatically generated by rust-bindgen 0.99.9 */

#[repr(C)]
pub struct Doggo {
    pub many: ::std::os::raw::c_int,
    pub wow: ::std::os::raw::c_char,
}

extern "C" {
    pub fn eleven_out_of_ten_majestic_af(pupper: *mut Doggo);
}

Users Guide

📚 Read the bindgen users guide here! 📚

MSRV

The minimum supported Rust version is 1.57.0.

No MSRV bump policy has been established yet, so MSRV may increase in any release.

The MSRV is the minimum Rust version that can be used to compile bindgen. However, bindgen can generate bindings that are compatible with Rust versions below the current MSRV.

API Reference

API reference documentation is on docs.rs

Environment Variables

In addition to the library API and executable command-line API, bindgen can be controlled through environment variables.

End-users should set these environment variables to modify bindgen's behavior without modifying the source code of direct consumers of bindgen.

  • BINDGEN_EXTRA_CLANG_ARGS: extra arguments to pass to clang
    • Arguments are whitespace-separated
    • Use shell-style quoting to pass through whitespace
    • Examples:
      • Specify alternate sysroot: --sysroot=/path/to/sysroot
      • Add include search path with spaces: -I"/path/with spaces"
  • BINDGEN_EXTRA_CLANG_ARGS_<TARGET>: similar to BINDGEN_EXTRA_CLANG_ARGS, but used to set per-target arguments to pass to clang. Useful to set system include directories in a target-specific way in cross-compilation environments with multiple targets. Has precedence over BINDGEN_EXTRA_CLANG_ARGS.

Additionally, bindgen uses libclang to parse C and C++ header files. To modify how bindgen searches for libclang, see the clang-sys documentation. For more details on how bindgen uses libclang, see the bindgen users guide.

Releases

We don't follow a specific release calendar, but if you need a release please file an issue requesting that (ping @emilio for increased effectiveness).

Contributing

See CONTRIBUTING.md for hacking on bindgen!