From: Asuna Yang <spriteovo@gmail.com>

Add a new `bindgen-backend-option` Kconfig function to test whether the
bindgen backend supports a given flag.

A subsequent commit will use this function to test for RISC-V extension
flags.

Signed-off-by: Asuna Yang <SpriteOvO@gmail.com>
---
 scripts/Kconfig.include | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/scripts/Kconfig.include b/scripts/Kconfig.include
index d42042b6c9e2..5d4d29eed0b3 100644
--- a/scripts/Kconfig.include
+++ b/scripts/Kconfig.include
@@ -78,3 +78,8 @@ rustc-llvm-version := $(shell,$(srctree)/scripts/rustc-llvm-version.sh $(RUSTC))
 # If you are testing for unstable features, consider testing RUSTC_VERSION
 # instead, as features may have different completeness while available.
 rustc-option = $(success,trap "rm -rf .tmp_$$" EXIT; mkdir .tmp_$$; $(RUSTC) $(1) --crate-type=rlib /dev/null --out-dir=.tmp_$$ -o .tmp_$$/tmp.rlib)
+
+# $(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))

-- 
2.51.1

On 12/4/25 15:54, Asuna Yang wrote:
> From: Asuna Yang <spriteovo@gmail.com>
>
> Add a new `bindgen-backend-option` Kconfig function to test whether the
> bindgen backend supports a given flag.
>
> A subsequent commit will use this function to test for RISC-V extension
> flags.
>
> Signed-off-by: Asuna Yang <SpriteOvO@gmail.com>
> ---
>  scripts/Kconfig.include | 5 +++++
>  1 file changed, 5 insertions(+)
>
> diff --git a/scripts/Kconfig.include b/scripts/Kconfig.include
> index d42042b6c9e2..5d4d29eed0b3 100644
> --- a/scripts/Kconfig.include
> +++ b/scripts/Kconfig.include
> @@ -78,3 +78,8 @@ rustc-llvm-version := $(shell,$(srctree)/scripts/rustc-llvm-version.sh $(RUSTC))
>  # If you are testing for unstable features, consider testing RUSTC_VERSION
>  # instead, as features may have different completeness while available.
>  rustc-option = $(success,trap "rm -rf .tmp_$$" EXIT; mkdir .tmp_$$; $(RUSTC) $(1) --crate-type=rlib /dev/null --out-dir=.tmp_$$ -o .tmp_$$/tmp.rlib)
> +
> +# $(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)

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

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...

> 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...

Didn't realize that I should pass a `-x` to the backend. It works now, 
I'll include it in the next revision. Thanks.