add rust-analyzer make target

This target creates ${objtree}/rust-project.json which can be read by
rust-analyzer to help with autocompletion for the kernel crate.

The raw bindings do not work yet, as rust-analyzer seems to have a
problem with the include macro.

Co-authored-by: Boris-Chengbiao Zhou <bobo1239@web.de>
Co-authored-by: Miguel Ojeda <ojeda@kernel.org>
Signed-off-by: Finn Behrens <me@kloenk.de>

Author: 3 people

Documentation/rust/quick-start.rst

@@ -155,11 +155,8 @@ definition, and other features.
 ``rust-analyzer`` will need to be
 `configured <https://rust-analyzer.github.io/manual.html#non-cargo-based-projects>`_
 to work with the kernel by adding a ``rust-project.json`` file in the root folder.
-The example ``Documentation/rust/rust-project.json`` can
-be used after updating ``sysroot_src`` and including the relevant modules.
-The path to ``sysroot_src`` is given by::
-
-    $(rustc --print sysroot)/lib/rustlib/src/rust/library
+A ``rust-project.json`` can be generated by building the Make target ``rust-analyzer``,
+which will create a ``rust-project.json`` in the root of the output directory.
 
 
 Configuration

Documentation/rust/rust-project.json

@@ -1738,6 +1738,8 @@ help:
 	@echo  '		    is formatted, printing a diff otherwise.'
 	@echo  '  rustdoc	  - Generate Rust documentation'
 	@echo  '		    (requires kernel .config)'
+	@echo  '  rust-analyzer	  - Generate rust-project.json rust-analyzer support file'
+	@echo  '		    (requires kernel .config)'
 	@echo  ''
 	@$(if $(dtstree), \
 		echo 'Devicetree:'; \
@@ -1830,6 +1832,10 @@ rustfmt:
 rustfmtcheck:
 	find -name '*.rs' | xargs $(RUSTFMT) --check
 
+# IDE support targets
+PHONY += rust-analyzer
+rust-analyzer: prepare0
+	$(Q)$(MAKE) $(build)=rust $@
 
 # Misc
 # ---------------------------------------------------------------------------

Makefile

@@ -129,6 +129,9 @@ quiet_cmd_rustc_library = $(if $(skip_clippy),RUSTC,$(RUSTC_OR_CLIPPY_QUIET)) L
 rustc_sysroot = $(shell $(RUSTC) $(rustc_flags) --print sysroot)
 RUST_LIB_SRC ?= $(rustc_sysroot)/lib/rustlib/src/rust/library
 
+rust-analyzer:
+	$(Q)$(srctree)/scripts/generate_rust_analyzer.py $(srctree) $(objtree) $(RUST_LIB_SRC) $(objtree)/rust/bindings_generated.rs > $(objtree)/rust-project.json
+
 .SECONDEXPANSION:
 $(objtree)/rust/core.o: private skip_clippy = 1
 $(objtree)/rust/core.o: $$(RUST_LIB_SRC)/core/src/lib.rs FORCE

rust/Makefile

@@ -0,0 +1,135 @@
+#!/usr/bin/env python3
+"""generate_rust_analyzer - Generates the `rust-project.json` file for `rust-analyzer`.
+"""
+
+import argparse
+import json
+import logging
+import pathlib
+import sys
+
+def generate_crates(srctree, objtree, sysroot_src, bindings_file):
+    # Generate the configuration list.
+    cfg = []
+    with open(objtree / "include" / "generated" / "rustc_cfg") as fd:
+        for line in fd:
+            line = line.replace("--cfg=", "")
+            line = line.replace("\n", "")
+            cfg.append(line)
+
+    # Now fill the crates list -- dependencies need to come first.
+    #
+    # Avoid O(n^2) iterations by keeping a map of indexes.
+    crates = []
+    crates_indexes = {}
+
+    def append_crate(display_name, root_module, is_workspace_member, deps, cfg):
+        crates_indexes[display_name] = len(crates)
+        crates.append({
+            "display_name": display_name,
+            "root_module": str(root_module),
+            "is_workspace_member": is_workspace_member,
+            "deps": [{"crate": crates_indexes[dep], "name": dep} for dep in deps],
+            "cfg": cfg,
+            "edition": "2018",
+            "env": {
+                "RUST_MODFILE": "This is only for rust-analyzer"
+            }
+        })
+
+    # First, the ones in `rust/` since they are a bit special.
+    append_crate(
+        "core",
+        sysroot_src / "core" / "src" / "lib.rs",
+        False,
+        [],
+        [],
+    )
+
+    append_crate(
+        "compiler_builtins",
+        srctree / "rust" / "compiler_builtins.rs",
+        True,
+        [],
+        [],
+    )
+
+    append_crate(
+        "alloc",
+        sysroot_src / "alloc" / "src" / "lib.rs",
+        False,
+        ["core", "compiler_builtins"],
+        [],
+    )
+
+    append_crate(
+        "module",
+        srctree / "rust" / "module.rs",
+        True,
+        [],
+        [],
+    )
+    crates[-1]["proc_macro_dylib_path"] = "rust/libmodule.so"
+
+    append_crate(
+        "kernel",
+        srctree / "rust" / "kernel" / "lib.rs",
+        True,
+        ["core", "alloc", "module"],
+        cfg,
+    )
+    crates[-1]["env"]["RUST_BINDINGS_FILE"] = str(bindings_file.resolve(True))
+    crates[-1]["source"] = {
+        "include_dirs": [
+            str(srctree / "rust" / "kernel"),
+            str(objtree / "rust")
+        ],
+        "exclude_dirs": [],
+    }
+
+    # Then, the rest outside of `rust/`.
+    #
+    # We explicitly mention the top-level folders we want to cover.
+    for folder in ("samples", "drivers"):
+        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():
+                continue
+
+            logging.info("Adding %s", name)
+            append_crate(
+                name,
+                path,
+                True,
+                ["core", "alloc", "kernel"],
+                cfg,
+            )
+
+    return crates
+
+def main():
+    parser = argparse.ArgumentParser()
+    parser.add_argument('--verbose', '-v', action='store_true')
+    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("bindings_file", type=pathlib.Path)
+    args = parser.parse_args()
+
+    logging.basicConfig(
+        format="[%(asctime)s] [%(levelname)s] %(message)s",
+        level=logging.INFO if args.verbose else logging.WARNING
+    )
+
+    rust_project = {
+        "crates": generate_crates(args.srctree, args.objtree, args.sysroot_src, args.bindings_file),
+        "sysroot_src": str(args.sysroot_src),
+    }
+
+    json.dump(rust_project, sys.stdout, sort_keys=True, indent=4)
+
+if __name__ == "__main__":
+    main()