scripts: make rust-analyzer for out-of-tree modules

Adds support for out-of-tree rust modules to use the `rust-analyzer`
make target to generate the rust-project.json file.

The change involves adding an optional parameter `external_src` to the
`generate_rust_analyzer.py` which expects the path to the out-of-tree
module's source directory. When this parameter is passed, I have chosen
not to add the non-core modules (samples and drivers) into the result
since these are not expected to be used in third party modules. Related
changes are also made to the Makefile and rust/Makefile allowing the
`rust-analyzer` target to be used for out-of-tree modules as well.

Signed-off-by: Vinay Varma <[email protected]>

Author: vvarma

Makefile

@@ -1831,11 +1831,6 @@ rustfmt:
 rustfmtcheck: rustfmt_flags = --check
 rustfmtcheck: rustfmt
 
-# IDE support targets
-PHONY += rust-analyzer
-rust-analyzer:
-	$(Q)$(MAKE) $(build)=rust $@
-
 # Misc
 # ---------------------------------------------------------------------------
 
@@ -1888,6 +1883,7 @@ help:
 	@echo  '  modules         - default target, build the module(s)'
 	@echo  '  modules_install - install the module'
 	@echo  '  clean           - remove generated files in module directory only'
+	@echo  '  rust-analyzer	  - generate rust-project.json rust-analyzer support file'
 	@echo  ''
 
 endif # KBUILD_EXTMOD
@@ -2022,6 +2018,12 @@ quiet_cmd_tags = GEN     $@
 tags TAGS cscope gtags: FORCE
 	$(call cmd,tags)
 
+# IDE support targets
+PHONY += rust-analyzer
+rust-analyzer:
+	$(Q)$(MAKE) $(build)=rust $@
+
+
 # Script to generate missing namespace dependencies
 # ---------------------------------------------------------------------------
 

rust/Makefile

@@ -388,9 +388,14 @@ quiet_cmd_rustc_library = $(if $(skip_clippy),RUSTC,$(RUSTC_OR_CLIPPY_QUIET)) L
 	sed -i '/^\#/d' $(depfile) \
 	$(if $(rustc_objcopy),;$(OBJCOPY) $(rustc_objcopy) $@)
 
+# We conditionally use abs_{srctree,objtree} for external modules so that
+# the lsp (rust-analyzer) can find the path to the kernel source files
 rust-analyzer:
-	$(Q)$(srctree)/scripts/generate_rust_analyzer.py $(srctree) $(objtree) \
-		$(RUST_LIB_SRC) > $(objtree)/rust-project.json
+	$(Q)$(srctree)/scripts/generate_rust_analyzer.py \
+		$(if $(KBUILD_EXTMOD),$(abs_srctree),$(srctree)) \
+		$(if $(KBUILD_EXTMOD),$(abs_objtree),$(objtree)) \
+		$(RUST_LIB_SRC) $(KBUILD_EXTMOD) > \
+		$(if $(KBUILD_EXTMOD),$(extmod_prefix),$(objtree))/rust-project.json
 
 $(obj)/core.o: private skip_clippy = 1
 $(obj)/core.o: private skip_flags = -Dunreachable_pub

scripts/generate_rust_analyzer.py

@@ -8,8 +8,9 @@
 import logging
 import pathlib
 import sys
+import os
 
-def generate_crates(srctree, objtree, sysroot_src):
+def generate_crates(srctree, objtree, sysroot_src, external_src):
     # Generate the configuration list.
     cfg = []
     with open(objtree / "include" / "generated" / "rustc_cfg") as fd:
@@ -65,7 +66,7 @@ def append_crate(display_name, root_module, deps, cfg=[], is_workspace_member=Tr
         [],
         is_proc_macro=True,
     )
-    crates[-1]["proc_macro_dylib_path"] = "rust/libmacros.so"
+    crates[-1]["proc_macro_dylib_path"] = f"{objtree}/rust/libmacros.so"
 
     append_crate(
         "build_error",
@@ -98,13 +99,15 @@ def append_crate(display_name, root_module, deps, cfg=[], is_workspace_member=Tr
     # Then, the rest outside of `rust/`.
     #
     # We explicitly mention the top-level folders we want to cover.
-    for folder in ("samples", "drivers"):
+    extra_src_dirs = ["samples", "drivers"] if external_src is None else [external_src]
+
+    for folder in extra_src_dirs:
         for path in (srctree / folder).rglob("*.rs"):
             logging.info("Checking %s", path)
             name = path.name.replace(".rs", "")
 
             # Skip those that are not crate roots.
-            if f"{name}.o" not in open(path.parent / "Makefile").read():
+            if os.path.exists(path.parent / "Makefile") and f"{name}.o" not in open(path.parent / "Makefile").read():
                 continue
 
             logging.info("Adding %s", name)
@@ -123,6 +126,7 @@ def main():
     parser.add_argument("srctree", type=pathlib.Path)
     parser.add_argument("objtree", type=pathlib.Path)
     parser.add_argument("sysroot_src", type=pathlib.Path)
+    parser.add_argument("exttree", type=pathlib.Path, nargs='?')
     args = parser.parse_args()
 
     logging.basicConfig(
@@ -131,7 +135,7 @@ def main():
     )
 
     rust_project = {
-        "crates": generate_crates(args.srctree, args.objtree, args.sysroot_src),
+        "crates": generate_crates(args.srctree, args.objtree, args.sysroot_src, args.exttree),
         "sysroot_src": str(args.sysroot_src),
     }