enum and define with the same name collide

[deweerdt]

Input C/C++ Header

enum {
        A =
#define A 0
                A,
} anenum;

Bindgen Invokation

bindgen::Builder::default()
    .header("input.h")
    .generate()
    .unwrap()

Actual Results

       Fresh bindgen v0.23.1                                                                                                                                                                                                                                                                                                        Compiling math_dot_h v0.1.0 (file:///home/def/p/rust/math_dot_h)
     Running `rustc --crate-name math_dot_h src/lib.rs --crate-type lib --emit=dep-info,link -C debuginfo=2 -C metadata=93892b9e7e7b815c -C extra-filename=-93892b9e7e7b815c --out-dir /home/def/p/rust/math_dot_h/target/debug/deps -L dependency=/home/def/p/rust/math_dot_h/target/debug/deps`
error[E0428]: a value named `A` has already been defined in this module
 --> /home/def/p/rust/math_dot_h/target/debug/build/math_dot_h-7f0a85db403a8610/out/bindings.rs:4:1
  |
3 | pub const A: ::std::os::raw::c_uint = 0;
  | ---------------------------------------- previous definition of `A` here
4 | pub const A: _bindgen_ty_1 = _bindgen_ty_1::A;
  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `A` already defined

error: aborting due to previous error

error: Could not compile `math_dot_h`.

Caused by:
  process didn't exit successfully: `rustc --crate-name math_dot_h src/lib.rs --crate-type lib --emit=dep-info,link -C debuginfo=2 -C metadata=93892b9e7e7b815c -C extra-filename=-93892b9e7e7b815c --out-dir /home/def/p/rust/math_dot_h/target/debug/deps -L dependency=/home/def/p/rust/math_dot_h/target/debug/deps` (exit code: 101)

Expected Results

No compilation error, both the enum and the define have their own name space.

This is problematic IRL because math.h uses this construct to define FP_* constants:
https://sourceware.org/git/?p=glibc.git;a=blob;f=math/math.h;h=cfaed0ed98013830421afdf1ba6f13c01702831d;hb=HEAD#l318

enum                                                                                                                                                                                                                                                                                                                               {                                                                                                                                                                                                                                                                                                                                  FP_NAN =                                                                                                                                                                                                                                                                                                                     # define FP_NAN 0                                                                                                                                                                                                                                                                                                                      FP_NAN,                                                                                                                                                                                                                                                                                                                        FP_INFINITE =                                                                                                                                                                                                                                                                                                                # define FP_INFINITE 1                                                                                                                                                                                                                                                                                                                 FP_INFINITE,
    FP_ZERO =
# define FP_ZERO 2
      FP_ZERO,
    FP_SUBNORMAL =
# define FP_SUBNORMAL 3
      FP_SUBNORMAL,
    FP_NORMAL =
# define FP_NORMAL 4
      FP_NORMAL
  };

RUST_LOG=bindgen Output

   Compiling math_dot_h v0.1.0 (file:///home/def/p/rust/math_dot_h)
error[E0428]: a value named `A` has already been defined in this module
 --> /home/def/p/rust/math_dot_h/target/debug/build/math_dot_h-7f0a85db403a8610/out/bindings.rs:4:1
  |
3 | pub const A: ::std::os::raw::c_uint = 0;
  | ---------------------------------------- previous definition of `A` here
4 | pub const A: _bindgen_ty_1 = _bindgen_ty_1::A;
  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `A` already defined

error: aborting due to previous error

error: Could not compile `math_dot_h`.

To learn more, run the command again with --verbose.

[emilio]

That's... nasty...

What would be a good solution for this? I can allow you to ignore a given macro by name with a new method in ParseCallbacks, would that work for you?

[emilio]

To be more clear, I'm thinking in something like macro_parsing_behavior(&self, name: &str) -> MacroParsingBehavior.

with something like:

enum MacroParsingBehavior {
    TryToEvaluate,
    Ignore,
}

Or something like that.

[deweerdt]

Thanks for your quick response!

If i understand correctly, you're suggesting that i return Ignore for the definitions I know will also be used as defines? I believe that will work for me, yes.

In general, it feels like the two definitions should belong to two different namespaces, but i don't know enough about bindgen to suggest anything beyond offering my opinion.

[emilio]

Yeah, it's a kind of unfortunate trade-off between ease to use and features... In general bindgen doesn't need to do a lot of deduplicating at the root level because rust allows to differentiate struct foo {} from fn foo, and similar stuff.

We could either mangle stuff like enum_foo, struct_bar, etc... but that'd be really annoying, specially for C++ users... Oh well.

[retrry]

I've started seeing this behavior on bindgen 0.26. While bindgen 0.25 generated code without errors. Bindgen 0.26 started giving me errors:

error[E0428]: the name `FP_NAN` is defined multiple times
    --> /home/target/debug/build/ffmpeg-sys-026db31dcba0e79a/out/bindings.rs:2820:1
     |
491  | pub const FP_NAN: libc::c_int = 0;
     | ---------------------------------- previous definition of the value `FP_NAN` here
...
2820 | pub const FP_NAN: _bindgen_ty_1 = _bindgen_ty_1::FP_NAN;
     | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `FP_NAN` redefined here
     |
     = note: `FP_NAN` must be defined only once in the value namespace of this module

error[E0428]: the name `FP_INFINITE` is defined multiple times
    --> /home/target/debug/build/ffmpeg-sys-026db31dcba0e79a/out/bindings.rs:2821:1
     |
492  | pub const FP_INFINITE: libc::c_int = 1;
     | --------------------------------------- previous definition of the value `FP_INFINITE` here
...
2821 | pub const FP_INFINITE: _bindgen_ty_1 = _bindgen_ty_1::FP_INFINITE;
     | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `FP_INFINITE` redefined here
     |
     = note: `FP_INFINITE` must be defined only once in the value namespace of this module

error[E0428]: the name `FP_ZERO` is defined multiple times
    --> /home/target/debug/build/ffmpeg-sys-026db31dcba0e79a/out/bindings.rs:2822:1
     |
493  | pub const FP_ZERO: libc::c_int = 2;
     | ----------------------------------- previous definition of the value `FP_ZERO` here
...
2822 | pub const FP_ZERO: _bindgen_ty_1 = _bindgen_ty_1::FP_ZERO;
     | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `FP_ZERO` redefined here
     |
     = note: `FP_ZERO` must be defined only once in the value namespace of this module

error[E0428]: the name `FP_SUBNORMAL` is defined multiple times
    --> /home/target/debug/build/ffmpeg-sys-026db31dcba0e79a/out/bindings.rs:2823:1
     |
494  | pub const FP_SUBNORMAL: libc::c_int = 3;
     | ---------------------------------------- previous definition of the value `FP_SUBNORMAL` here
...
2823 | pub const FP_SUBNORMAL: _bindgen_ty_1 = _bindgen_ty_1::FP_SUBNORMAL;
     | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `FP_SUBNORMAL` redefined here
     |
     = note: `FP_SUBNORMAL` must be defined only once in the value namespace of this module

error[E0428]: the name `FP_NORMAL` is defined multiple times
    --> /home/target/debug/build/ffmpeg-sys-026db31dcba0e79a/out/bindings.rs:2824:1
     |
495  | pub const FP_NORMAL: libc::c_int = 4;
     | ------------------------------------- previous definition of the value `FP_NORMAL` here
...
2824 | pub const FP_NORMAL: _bindgen_ty_1 = _bindgen_ty_1::FP_NORMAL;
     | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `FP_NORMAL` redefined here
     |
     = note: `FP_NORMAL` must be defined only once in the value namespace of this module

error: aborting due to 5 previous errors

error: Could not compile `ffmpeg-sys`.

As a workaround I'm just ignoring those types:

        .hide_type("FP_NAN")
        .hide_type("FP_INFINITE")
        .hide_type("FP_ZERO")
        .hide_type("FP_SUBNORMAL")
        .hide_type("FP_NORMAL")

[gentoo90]

I've encountered the same error with bindgen-0.25.5 and clang-4.0.0 on linux.
Crate magick-rust.

$ LIBCLANG_PATH=/usr/lib/llvm/4/lib64 cargo build
   Compiling magick_rust v0.6.6 (file:///home/user/magick-rust)
    --> /home/user/magick-rust/target/debug/build/magick_rust-9bda580053656820/out/bindings.rs:4825:1
     |
747  | pub const FP_NAN: libc::c_uint = 0;
     | ----------------------------------- previous definition of the value `FP_NAN` here
...
4825 | pub const FP_NAN: _bindgen_ty_1 = _bindgen_ty_1::FP_NAN;
     | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `FP_NAN` redefined here
     |
     = note: `FP_NAN` must be defined only once in the value namespace of this module

error[E0428]: the name `FP_INFINITE` is defined multiple times
    --> /home/user/magick-rust/target/debug/build/magick_rust-9bda580053656820/out/bindings.rs:4826:1
     |
748  | pub const FP_INFINITE: libc::c_uint = 1;
     | ---------------------------------------- previous definition of the value `FP_INFINITE` here
...
4826 | pub const FP_INFINITE: _bindgen_ty_1 = _bindgen_ty_1::FP_INFINITE;
     | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `FP_INFINITE` redefined here
     |
     = note: `FP_INFINITE` must be defined only once in the value namespace of this module

error[E0428]: the name `FP_ZERO` is defined multiple times
    --> /home/user/magick-rust/target/debug/build/magick_rust-9bda580053656820/out/bindings.rs:4827:1
     |
749  | pub const FP_ZERO: libc::c_uint = 2;
     | ------------------------------------ previous definition of the value `FP_ZERO` here
...
4827 | pub const FP_ZERO: _bindgen_ty_1 = _bindgen_ty_1::FP_ZERO;
     | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `FP_ZERO` redefined here
     |
     = note: `FP_ZERO` must be defined only once in the value namespace of this module

error[E0428]: the name `FP_SUBNORMAL` is defined multiple times
    --> /home/user/magick-rust/target/debug/build/magick_rust-9bda580053656820/out/bindings.rs:4828:1
     |
750  | pub const FP_SUBNORMAL: libc::c_uint = 3;
     | ----------------------------------------- previous definition of the value `FP_SUBNORMAL` here
...
4828 | pub const FP_SUBNORMAL: _bindgen_ty_1 = _bindgen_ty_1::FP_SUBNORMAL;
     | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `FP_SUBNORMAL` redefined here
     |
     = note: `FP_SUBNORMAL` must be defined only once in the value namespace of this module

error[E0428]: the name `FP_NORMAL` is defined multiple times
    --> /home/user/magick-rust/target/debug/build/magick_rust-9bda580053656820/out/bindings.rs:4829:1
     |
751  | pub const FP_NORMAL: libc::c_uint = 4;
     | -------------------------------------- previous definition of the value `FP_NORMAL` here
...
4829 | pub const FP_NORMAL: _bindgen_ty_1 = _bindgen_ty_1::FP_NORMAL;
     | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `FP_NORMAL` redefined here
     |
     = note: `FP_NORMAL` must be defined only once in the value namespace of this module

[spacekookie]

Is there any update or progress on fixing this issue? I'm only affected by it via an external dependency so manually tweaking bindgen settings isn't really an option for me. And this is currently blocking a project 😞

[fitzgen]

I could imagine the BindgenContext carrying a map of name -> counter and writing a new pass over the IR right before codegen that bumps the appropriate entry's counter for each definition of any kind, and then appending the counter to the definition's name when its not the first time we've seen that name.

Essentially, moving our method/function overloading strategy up and out of codegen and use it for all definitions.

This should also solve #840

If anyone is interested in trying their hand at this, I can help mentor (cc @spacekookie )

[spacekookie]

Hey @fitzgen, I mean...I'd love to have a try at fixing this though I've only been writing Rust for ~2 months now and I'm rather green, especially when it comes to large Rust projects. If you're offering to mentor though, maybe get in touch with me via twitter or e-mail?