Declare common `cfg`s just once to reduce the size of rust-analyzer.json
from 30619 to 2624 lines.

Link: https://github.com/rust-lang/rust-analyzer/commit/2607c09fddef36da0d6f0a84625db5e20a5ebde3
Reviewed-by: Daniel Almeida <daniel.almeida@collabora.com>
Tested-by: Daniel Almeida <daniel.almeida@collabora.com>
Reviewed-by: Trevor Gross <tmgross@umich.edu>
Signed-off-by: Tamir Duberstein <tamird@gmail.com>
---
 scripts/generate_rust_analyzer.py | 21 ++++++++++++---------
 1 file changed, 12 insertions(+), 9 deletions(-)

diff --git a/scripts/generate_rust_analyzer.py b/scripts/generate_rust_analyzer.py
index 5f04e3785854..aa79b56ff6f4 100755
--- a/scripts/generate_rust_analyzer.py
+++ b/scripts/generate_rust_analyzer.py
@@ -29,6 +29,7 @@ class Crate(TypedDict):
     root_module: str
     is_workspace_member: bool
     deps: List[Dependency]
+    cfg_groups: List[str]
     cfg: List[str]
     edition: Literal["2021"]
     env: Dict[str, str]
@@ -51,15 +52,8 @@ def generate_crates(
     sysroot_src: pathlib.Path,
     external_src: pathlib.Path,
     crates_cfgs: DefaultDict[str, List[str]],
+    cfg_groups: List[str],
 ) -> List[Crate]:
-    # 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.
     crates: List[Crate] = []
 
@@ -76,6 +70,9 @@ def generate_crates(
             "root_module": str(root_module),
             "is_workspace_member": is_workspace_member,
             "deps": deps,
+            # `cfg_groups` contain the configs generated by the kernel build system; upstream
+            # (sysroot) crates are not aware of them.
+            "cfg_groups": cfg_groups if is_workspace_member else [],
             "cfg": cfg,
             "edition": "2021",
             "env": {
@@ -298,7 +295,7 @@ def generate_crates(
                 name,
                 path,
                 deps=[core, kernel],
-                cfg=cfg,
+                cfg=[],
             )
 
     return crates
@@ -338,6 +335,10 @@ def main() -> None:
         for crate, _, vals in (cfg.partition("=") for cfg in args.cfgs)
     }
 
+    # Generate the configuration list.
+    with open(args.objtree / "include" / "generated" / "rustc_cfg") as fd:
+        cfg_groups = {"rustc_cfg": [line.lstrip("--cfg=").rstrip("\n") for line in fd]}
+
     rust_project = {
         "crates": generate_crates(
             args.srctree,
@@ -345,8 +346,10 @@ def main() -> None:
             args.sysroot_src,
             args.exttree,
             defaultdict(list, crates_cfg),
+            list(cfg_groups.keys()),
         ),
         "sysroot": str(args.sysroot),
+        "cfg_groups": cfg_groups,
     }
 
     json.dump(rust_project, sys.stdout, sort_keys=True, indent=4)

-- 
2.49.0