[PATCH v6 3/4] rust: add a Kconfig function to test for support of bindgen options

[Asuna Yang]

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 <xinrui.riscv at isrc.iscas.ac.cn>
---
 scripts/Kconfig.include | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/scripts/Kconfig.include b/scripts/Kconfig.include
index d42042b6c9e2..9954b8093fab 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 = $(success,$(BINDGEN) /dev/null -- -x c --target=$(BINDGEN_TARGET) $(1))

-- 
2.51.1