[PATCH v3 2/2] scripts: generate_rust_analyzer.py: fix IDE support for primitive types

[Jesung Yang via B4 Relay <devnull+y.j3ms.n.gmail.com@kernel.org>]

From: Jesung Yang <y.j3ms.n@gmail.com>

Update `generate_rust_analyzer.py` so that the generated
`rust-project.json` contains the `sysroot_src` field with
`"crate_attrs": ["no_std"]` specified for relevant crates. This ensures
that rust-analyzer provides proper IDE support for inherent methods of
primitive types.

Since commit 50384460c68f ("Rewrite method resolution to follow rustc
more closely") to rust-analyzer, it no longer provides language server
features like code completion and go-to-definition for inherent methods
of primitive types when sysroot crates (e.g., `core`, `std`) are inlined
in `rust-project.json` [1]. As `generate_rust_analyzer.py` currently
inlines these crates, our setup is affected by this change.

Specifying the `sysroot_src` field restores this functionality by
allowing rust-analyzer to locate sysroot crates by itself. However, this
causes `std` to be treated as a dependency for all local crates by
default. To align with our compilation settings, provide the `no_std`
attribute via the `crate_attrs` field, as the `-Zcrate-attr=no_std`
compiler flag is not visible to rust-analyzer. This combined approach
removes manual manipulation of sysroot dependencies while preventing
incorrect symbol resolution against the standard library.

Note that this configuration requires rust-analyzer release 2025-12-22
(v0.3.2727) or later, which introduced support for the `crate_attrs`
field.

Link: https://rust-lang.zulipchat.com/#narrow/channel/x/topic/x/near/561607963 [1]
Link: https://rust-for-linux.zulipchat.com/#narrow/channel/x/topic/x/near/561607753
Signed-off-by: Jesung Yang <y.j3ms.n@gmail.com>
---
 scripts/generate_rust_analyzer.py | 24 ++++++++++++++++++++++--
 1 file changed, 22 insertions(+), 2 deletions(-)

diff --git a/scripts/generate_rust_analyzer.py b/scripts/generate_rust_analyzer.py
index a4d25bb8b602..ab399f6044fa 100755
--- a/scripts/generate_rust_analyzer.py
+++ b/scripts/generate_rust_analyzer.py
@@ -52,9 +52,11 @@ class CrateWithGenerated(Crate):
     source: Source
 
 
-class RustProject(TypedDict):
+# TODO: use `typing.NotRequired` when Python 3.11 is adopted.
+class RustProject(TypedDict, total=False):
     crates: List[Crate]
     sysroot: str
+    sysroot_src: str
 
 
 Version = tuple[int, int, int]
@@ -80,6 +82,12 @@ BASELINES: List[RaVersionInfo] = [
         "ra_version": (0, 3, 1877),
         "rust_version": (1, 78, 0),
     },
+    # v0.3.2727, released on 2025-12-22; v0.3.2743 is shipped with the rustup 1.94 toolchain.
+    {
+        "release_date": datetime.strptime("2025-12-22", "%Y-%m-%d"),
+        "ra_version": (0, 3, 2727),
+        "rust_version": (1, 94, 0),
+    },
 ]
 
 DEFAULT_BASELINE: RaVersionInfo = BASELINES[0]
@@ -407,7 +415,7 @@ def generate_rust_project(
     cfgs: List[str],
     core_edition: str,
 ) -> RustProject:
-    assert len(BASELINES) == 1, "Exhaustiveness check: update if branches!"
+    assert len(BASELINES) == 2, "Exhaustiveness check: update if branches!"
 
     ctx: RaVersionCtx
 
@@ -422,6 +430,18 @@ def generate_rust_project(
             ),
             "sysroot": str(sysroot),
         }
+    elif version_info["ra_version"] == (0, 3, 2727):
+        ctx = {
+            "use_crate_attrs": True,
+            "manual_sysroot_crates": False,
+        }
+        return {
+            "crates": generate_crates(
+                ctx, srctree, objtree, sysroot_src, external_src, cfgs, core_edition
+            ),
+            "sysroot": str(sysroot),
+            "sysroot_src": str(sysroot_src),
+        }
     else:
         assert False, "Unreachable!"
 

-- 
2.52.0