[PATCH v2 19/20] rust: syn: enable support in kbuild

Miguel Ojeda
2025-11-24T15:20:20Z

With all the new files in place and ready from the new crate, enable
the support for it in the build system.

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>
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
---
Makefile | 1 +
rust/Makefile | 37 ++++++++++++++++++++++++++++---
scripts/generate_rust_analyzer.py | 7 ++++++
3 files changed, 42 insertions(+), 3 deletions(-)

diff --git a/Makefile b/Makefile
index 85da055e4f00..96ddbaae7e12 100644
--- a/Makefile
+++ b/Makefile
@@ -1835,6 +1835,7 @@ rustfmt:
\( \
-path $(srctree)/rust/proc-macro2 \
-o -path $(srctree)/rust/quote \
+ -o -path $(srctree)/rust/syn \
\) -prune -o \
-type f -a -name '*.rs' -a ! -name '*generated*' -print \
| xargs $(RUSTFMT) $(rustfmt_flags)
diff --git a/rust/Makefile b/rust/Makefile
index 4f4a00594142..8988ecf32531 100644
--- a/rust/Makefile
+++ b/rust/Makefile
@@ -27,7 +27,7 @@ endif

obj-$(CONFIG_RUST) += exports.o

-always-$(CONFIG_RUST) += libproc_macro2.rlib libquote.rlib
+always-$(CONFIG_RUST) += libproc_macro2.rlib libquote.rlib libsyn.rlib

always-$(CONFIG_RUST_KERNEL_DOCTESTS) += doctests_kernel_generated.rs
always-$(CONFIG_RUST_KERNEL_DOCTESTS) += doctests_kernel_generated_kunit.c
@@ -101,6 +101,22 @@ quote-flags := \
--extern proc_macro2 \
$(call cfgs-to-flags,$(quote-cfgs))

+# `extra-traits`, `fold` and `visit` may be enabled if needed.
+syn-cfgs := \
+ feature="clone-impls" \
+ feature="derive" \
+ feature="full" \
+ feature="parsing" \
+ feature="printing" \
+ feature="proc-macro" \
+ feature="visit-mut"
+
+syn-flags := \
+ --cap-lints=allow \
+ --extern proc_macro2 \
+ --extern quote \
+ $(call cfgs-to-flags,$(syn-cfgs))
+
# `rustdoc` did not save the target modifiers, thus workaround for
# the time being (https://github.com/rust-lang/rust/issues/144521).
rustdoc_modifiers_workaround := $(if $(call rustc-min-version,108800),-Cunsafe-allow-abi-mismatch=fixed-x18)
@@ -161,11 +177,16 @@ rustdoc-quote: private skip_flags = $(quote-skip_flags)
rustdoc-quote: $(src)/quote/lib.rs rustdoc-clean rustdoc-proc_macro2 FORCE
+$(call if_changed,rustdoc)

+rustdoc-syn: private rustdoc_host = yes
+rustdoc-syn: private rustc_target_flags = $(syn-flags)
+rustdoc-syn: $(src)/syn/lib.rs rustdoc-clean rustdoc-quote FORCE
+ +$(call if_changed,rustdoc)
+
rustdoc-macros: private rustdoc_host = yes
rustdoc-macros: private rustc_target_flags = --crate-type proc-macro \
--extern proc_macro
rustdoc-macros: $(src)/macros/lib.rs rustdoc-clean rustdoc-proc_macro2 \
- rustdoc-quote FORCE
+ rustdoc-quote rustdoc-syn FORCE
+$(call if_changed,rustdoc)

# Starting with Rust 1.82.0, skipping `-Wrustdoc::unescaped_backticks` should
@@ -231,6 +252,10 @@ rusttestlib-quote: private rustc_target_flags = $(quote-flags)
rusttestlib-quote: $(src)/quote/lib.rs rusttestlib-proc_macro2 FORCE
+$(call if_changed,rustc_test_library)

+rusttestlib-syn: private rustc_target_flags = $(syn-flags)
+rusttestlib-syn: $(src)/syn/lib.rs rusttestlib-quote FORCE
+ +$(call if_changed,rustc_test_library)
+
rusttestlib-macros: private rustc_target_flags = --extern proc_macro
rusttestlib-macros: private rustc_test_library_proc = yes
rusttestlib-macros: $(src)/macros/lib.rs FORCE
@@ -488,6 +513,11 @@ $(obj)/libquote.rlib: private rustc_target_flags = $(quote-flags)
$(obj)/libquote.rlib: $(src)/quote/lib.rs $(obj)/libproc_macro2.rlib FORCE
+$(call if_changed_dep,rustc_procmacrolibrary)

+$(obj)/libsyn.rlib: private skip_clippy = 1
+$(obj)/libsyn.rlib: private rustc_target_flags = $(syn-flags)
+$(obj)/libsyn.rlib: $(src)/syn/lib.rs $(obj)/libquote.rlib FORCE
+ +$(call if_changed_dep,rustc_procmacrolibrary)
+
quiet_cmd_rustc_procmacro = $(RUSTC_OR_CLIPPY_QUIET) P $@
cmd_rustc_procmacro = \
$(RUSTC_OR_CLIPPY) $(rust_common_flags) $(rustc_target_flags) \
@@ -500,7 +530,7 @@ quiet_cmd_rustc_procmacro = $(RUSTC_OR_CLIPPY_QUIET) P $@

# Procedural macros can only be used with the `rustc` that compiled it.
$(obj)/$(libmacros_name): $(src)/macros/lib.rs $(obj)/libproc_macro2.rlib \
- $(obj)/libquote.rlib FORCE
+ $(obj)/libquote.rlib $(obj)/libsyn.rlib FORCE
+$(call if_changed_dep,rustc_procmacro)

$(obj)/$(libpin_init_internal_name): private rustc_target_flags = --cfg kernel
@@ -525,6 +555,7 @@ rust-analyzer:
--cfgs='core=$(core-cfgs)' $(core-edition) \
--cfgs='proc_macro2=$(proc_macro2-cfgs)' \
--cfgs='quote=$(quote-cfgs)' \
+ --cfgs='syn=$(syn-cfgs)' \
$(realpath $(srctree)) $(realpath $(objtree)) \
$(rustc_sysroot) $(RUST_LIB_SRC) $(if $(KBUILD_EXTMOD),$(srcroot)) \
> rust-project.json
diff --git a/scripts/generate_rust_analyzer.py b/scripts/generate_rust_analyzer.py
index 4faf153ed2ee..5b6f7b8d6918 100755
--- a/scripts/generate_rust_analyzer.py
+++ b/scripts/generate_rust_analyzer.py
@@ -100,6 +100,13 @@ def generate_crates(srctree, objtree, sysroot_src, external_src, cfgs, core_edit
cfg=crates_cfgs["quote"],
)

+ append_crate(
+ "syn",
+ srctree / "rust" / "syn" / "lib.rs",
+ ["proc_macro", "proc_macro2", "quote"],
+ cfg=crates_cfgs["syn"],
+ )
+
append_crate(
"macros",
srctree / "rust" / "macros" / "lib.rs",
--
2.52.0