[PATCH 3/4] scripts: generate_rust_analyzer.py: add type hints

[Tamir Duberstein <tamird@kernel.org>]

Python type hints allow static analysis tools like mypy to detect type
errors during development, improving the developer experience.

Python type hints have been present in the kernel since 2019 at the
latest; see commit 6ebf5866f2e8 ("kunit: tool: add Python wrappers for
running KUnit tests").

Add a subclass of `argparse.Namespace` to get type checking on the CLI
arguments.

Run `mypy --strict scripts/generate_rust_analyzer.py --python-version
3.9` to verify. Note that `mypy` no longer supports python < 3.9.

Tested-by: Daniel Almeida <daniel.almeida@collabora.com>
Reviewed-by: Daniel Almeida <daniel.almeida@collabora.com>
Reviewed-by: Trevor Gross <tmgross@umich.edu>
Signed-off-by: Tamir Duberstein <tamird@kernel.org>
---
 scripts/generate_rust_analyzer.py | 130 ++++++++++++++++++++++++++------------
 1 file changed, 90 insertions(+), 40 deletions(-)

diff --git a/scripts/generate_rust_analyzer.py b/scripts/generate_rust_analyzer.py
index bc79e4d8e8e7..2723154f207c 100755
--- a/scripts/generate_rust_analyzer.py
+++ b/scripts/generate_rust_analyzer.py
@@ -10,8 +10,9 @@ import os
 import pathlib
 import subprocess
 import sys
+from typing import Dict, Iterable, List, Literal, Optional, TypedDict
 
-def args_crates_cfgs(cfgs):
+def args_crates_cfgs(cfgs: List[str]) -> Dict[str, List[str]]:
     crates_cfgs = {}
     for cfg in cfgs:
         crate, vals = cfg.split("=", 1)
@@ -19,7 +20,43 @@ def args_crates_cfgs(cfgs):
 
     return crates_cfgs
 
-def generate_crates(srctree, objtree, sysroot_src, external_src, cfgs, core_edition):
+class Dependency(TypedDict):
+    crate: int
+    name: str
+
+
+class Source(TypedDict):
+    include_dirs: List[str]
+    exclude_dirs: List[str]
+
+
+class Crate(TypedDict):
+    display_name: str
+    root_module: str
+    is_workspace_member: bool
+    deps: List[Dependency]
+    cfg: List[str]
+    edition: str
+    env: Dict[str, str]
+
+
+class ProcMacroCrate(Crate):
+    is_proc_macro: Literal[True]
+    proc_macro_dylib_path: str  # `pathlib.Path` is not JSON serializable.
+
+
+class CrateWithGenerated(Crate):
+    source: Source
+
+
+def generate_crates(
+    srctree: pathlib.Path,
+    objtree: pathlib.Path,
+    sysroot_src: pathlib.Path,
+    external_src: Optional[pathlib.Path],
+    cfgs: List[str],
+    core_edition: str,
+) -> List[Crate]:
     # Generate the configuration list.
     cfg = []
     with open(objtree / "include" / "generated" / "rustc_cfg") as fd:
@@ -31,19 +68,19 @@ def generate_crates(srctree, objtree, sysroot_src, external_src, cfgs, core_edit
     # Now fill the crates list -- dependencies need to come first.
     #
     # Avoid O(n^2) iterations by keeping a map of indexes.
-    crates = []
-    crates_indexes = {}
+    crates: List[Crate] = []
+    crates_indexes: Dict[str, int] = {}
     crates_cfgs = args_crates_cfgs(cfgs)
 
     def build_crate(
-        display_name,
-        root_module,
-        deps,
+        display_name: str,
+        root_module: pathlib.Path,
+        deps: List[str],
         *,
-        cfg,
-        is_workspace_member,
-        edition,
-    ):
+        cfg: Optional[List[str]],
+        is_workspace_member: Optional[bool],
+        edition: Optional[str],
+    ) -> Crate:
         cfg = cfg if cfg is not None else []
         is_workspace_member = (
             is_workspace_member if is_workspace_member is not None else True
@@ -62,14 +99,14 @@ def generate_crates(srctree, objtree, sysroot_src, external_src, cfgs, core_edit
         }
 
     def append_proc_macro_crate(
-        display_name,
-        root_module,
-        deps,
+        display_name: str,
+        root_module: pathlib.Path,
+        deps: List[str],
         *,
-        cfg=None,
-        is_workspace_member=None,
-        edition=None,
-    ):
+        cfg: Optional[List[str]] = None,
+        is_workspace_member: Optional[bool] = None,
+        edition: Optional[str] = None,
+    ) -> None:
         crate = build_crate(
             display_name,
             root_module,
@@ -95,26 +132,26 @@ def generate_crates(srctree, objtree, sysroot_src, external_src, cfgs, core_edit
             .decode("utf-8")
             .strip()
         )
-        proc_macro_crate = {
+        proc_macro_crate: ProcMacroCrate = {
             **crate,
             "is_proc_macro": True,
             "proc_macro_dylib_path": str(objtree / "rust" / proc_macro_dylib_name),
         }
         return register_crate(proc_macro_crate)
 
-    def register_crate(crate):
+    def register_crate(crate: Crate) -> None:
         crates_indexes[crate["display_name"]] = len(crates)
         crates.append(crate)
 
     def append_crate(
-        display_name,
-        root_module,
-        deps,
+        display_name: str,
+        root_module: pathlib.Path,
+        deps: List[str],
         *,
-        cfg=None,
-        is_workspace_member=None,
-        edition=None,
-    ):
+        cfg: Optional[List[str]] = None,
+        is_workspace_member: Optional[bool] = None,
+        edition: Optional[str] = None,
+    ) -> None:
         return register_crate(
             build_crate(
                 display_name,
@@ -127,12 +164,12 @@ def generate_crates(srctree, objtree, sysroot_src, external_src, cfgs, core_edit
         )
 
     def append_sysroot_crate(
-        display_name,
-        deps,
+        display_name: str,
+        deps: List[str],
         *,
-        cfg=None,
-        edition=None,
-    ):
+        cfg: Optional[List[str]] = None,
+        edition: Optional[str] = None,
+    ) -> None:
         return append_crate(
             display_name,
             sysroot_src / display_name / "src" / "lib.rs",
@@ -210,9 +247,9 @@ def generate_crates(srctree, objtree, sysroot_src, external_src, cfgs, core_edit
     )
 
     def append_crate_with_generated(
-        display_name,
-        deps,
-    ):
+        display_name: str,
+        deps: List[str],
+    ) -> None:
         crate = build_crate(
             display_name,
             srctree / "rust"/ display_name / "lib.rs",
@@ -222,7 +259,7 @@ def generate_crates(srctree, objtree, sysroot_src, external_src, cfgs, core_edit
             edition=None,
         )
         crate["env"]["OBJTREE"] = str(objtree.resolve(True))
-        crate_with_generated = {
+        crate_with_generated: CrateWithGenerated = {
             **crate,
             "source": {
                 "include_dirs": [
@@ -238,7 +275,7 @@ def generate_crates(srctree, objtree, sysroot_src, external_src, cfgs, core_edit
     append_crate_with_generated("uapi", ["core", "ffi", "pin_init"])
     append_crate_with_generated("kernel", ["core", "macros", "build_error", "pin_init", "ffi", "bindings", "uapi"])
 
-    def is_root_crate(build_file, target):
+    def is_root_crate(build_file: pathlib.Path, target: str) -> bool:
         try:
             return f"{target}.o" in open(build_file).read()
         except FileNotFoundError:
@@ -247,7 +284,9 @@ def generate_crates(srctree, objtree, sysroot_src, external_src, cfgs, core_edit
     # Then, the rest outside of `rust/`.
     #
     # We explicitly mention the top-level folders we want to cover.
-    extra_dirs = map(lambda dir: srctree / dir, ("samples", "drivers"))
+    extra_dirs: Iterable[pathlib.Path] = (
+        srctree / dir for dir in ("samples", "drivers")
+    )
     if external_src is not None:
         extra_dirs = [external_src]
     for folder in extra_dirs:
@@ -270,7 +309,7 @@ def generate_crates(srctree, objtree, sysroot_src, external_src, cfgs, core_edit
 
     return crates
 
-def main():
+def main() -> None:
     parser = argparse.ArgumentParser()
     parser.add_argument('--verbose', '-v', action='store_true')
     parser.add_argument('--cfgs', action='append', default=[])
@@ -280,7 +319,18 @@ def main():
     parser.add_argument("sysroot", type=pathlib.Path)
     parser.add_argument("sysroot_src", type=pathlib.Path)
     parser.add_argument("exttree", type=pathlib.Path, nargs="?")
-    args = parser.parse_args()
+
+    class Args(argparse.Namespace):
+        verbose: bool
+        cfgs: List[str]
+        srctree: pathlib.Path
+        objtree: pathlib.Path
+        sysroot: pathlib.Path
+        sysroot_src: pathlib.Path
+        exttree: Optional[pathlib.Path]
+        core_edition: str
+
+    args = parser.parse_args(namespace=Args())
 
     logging.basicConfig(
         format="[%(asctime)s] [%(levelname)s] %(message)s",

-- 
2.52.0