[PATCH v5 3/4] rust: add a Kconfig function to test for support of bindgen options

[Vivian Wang]

On 12/4/25 20:33, Asuna Yang wrote:
> On 12/4/25 5:06 PM, Vivian Wang wrote:
>
>>> +
>>> +# $(bindgen-backend-option,<flag>)
>>> +# Return y if bindgen backend supports <flag>, n otherwise
>>> +# For now, the backend refers only to libclang, so more
>>> specifically, this function tests whether the given flag is
>>> recognized by the libclang used by bindgen.
>>> +bindgen-backend-option = $(success,trap "rm -f .tmp_$$.h" EXIT;
>>> touch .tmp_$$.h; $(BINDGEN) .tmp_$$.h -- --target=$(BINDGEN_TARGET)
>>> $(1))
>>>
>> Can probably be simplified down to:
>>
>> $(BINDGEN) /dev/null -- -x c --target=$(BINDGEN_TARGET) $(1)
>>
>
> bindgen is sensitive to file extensions. If the file is not .h or
> .hpp, it complains:
>
> panicked at bindgen/ir/context.rs:562:15:
> libclang error; possible causes include:
> - Invalid flag syntax
> - Unrecognized flags
> - Invalid flag arguments
> - File I/O errors
> - Host vs. target architecture mismatch 

That's so weird... I can't reproduce this if i pass -x c to bindgen,
like this:

$ bindgen --version
bindgen 0.72.1
$ bindgen /dev/null
panicked at /build/rust-bindgen-unwrapped-0.72.1-vendor/bindgen-0.72.1/ir/context.rs:562:15:
libclang error; possible causes include:
- Invalid flag syntax
- Unrecognized flags
- Invalid flag arguments
- File I/O errors
- Host vs. target architecture mismatch
If you encounter an error missing from this list, please file an issue or a PR!
$ bindgen /dev/null -- -x c
Failed to run rustfmt: No such file or directory (os error 2) (non-fatal, continuing)
/* automatically generated by rust-bindgen 0.72.1 */

The -x argument should explicitly tell (lib)clang what language the file
is without needing an extension. I don't know why it's not working for
you...