rust: kbuild: support using libraries in `rustc_procmacro`

Proc macros such as `macros` and `pin-init` will need the ability to use
libraries such as `syn` (added later) in the `rustc_procmacro` command.

Thus add the support for it.

Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Gary Guo <gary@garyguo.net>
Tested-by: Gary Guo <gary@garyguo.net>
Tested-by: Jesung Yang <y.j3ms.n@gmail.com>
Link: https://patch.msgid.link/20251124151837.2184382-6-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

diff --git a/rust/Makefile b/rust/Makefile
index 6fdab341fc48b6906e50ee94e8aacff226125225..0288ca8d270cf730753282e2941b43e2a4c131a7 100644 (file)
--- a/rust/Makefile
+++ b/rust/Makefile
@@ -437,7 +437,7 @@ quiet_cmd_rustc_procmacro = $(RUSTC_OR_CLIPPY_QUIET) P $@
                -Clinker-flavor=gcc -Clinker=$(HOSTCC) \
                -Clink-args='$(call escsq,$(KBUILD_PROCMACROLDFLAGS))' \
                --emit=dep-info=$(depfile) --emit=link=$@ --extern proc_macro \
-               --crate-type proc-macro \
+               --crate-type proc-macro -L$(objtree)/$(obj) \
                --crate-name $(patsubst lib%.$(libmacros_extension),%,$(notdir $@)) \
                @$(objtree)/include/generated/rustc_cfg $<