Add the proc_macro crate from the rust sysroot to the
rust-project.json file used by rust-analyzer. This allows
rust-analyzer to autocomplete items from the proc_macro crate inside
the macros crate.

This also adds std and alloc only to be used by proc_macro and
macros. This does not add the dependencies of those crates as this is
sufficent for rust-analyzer to have a basic autocompletion support
without having to worry about all the dependencies std usually needs.
alloc is added, as e.g. std::vec just reexports from alloc, so that
macros can use autocompletion for Vec and similar.

Signed-off-by: Fiona Behrens <me@kloenk.dev>
---
 scripts/generate_rust_analyzer.py | 26 +++++++++++++++++++++++++-
 1 file changed, 25 insertions(+), 1 deletion(-)

diff --git a/scripts/generate_rust_analyzer.py b/scripts/generate_rust_analyzer.py
index 09e1d166d8d2..747b5ed6c857 100755
--- a/scripts/generate_rust_analyzer.py
+++ b/scripts/generate_rust_analyzer.py
@@ -64,10 +64,34 @@ def generate_crates(srctree, objtree, sysroot_src, external_src, cfgs):
         [],
     )
 
+    # alloc only for std/proc_macros/macros
+    append_crate(
+        "alloc",
+        sysroot_src / "alloc" / "src" / "lib.rs",
+        ["core"],
+        is_workspace_member=False,
+    )
+
+    # std only for proc_macros/macros
+    append_crate(
+        "std",
+        sysroot_src / "std" / "src" / "lib.rs",
+        ["core", "alloc"],
+        is_workspace_member=False,
+    )
+
+    # proc_macro for macros crate
+    append_crate(
+        "proc_macro",
+        sysroot_src / "proc_macro" / "src" / "lib.rs",
+        ["std", "core"],
+        is_workspace_member=False,
+    )
+
     append_crate(
         "macros",
         srctree / "rust" / "macros" / "lib.rs",
-        [],
+        ["std", "proc_macro"],
         is_proc_macro=True,
     )
     crates[-1]["proc_macro_dylib_path"] = f"{objtree}/rust/libmacros.so"
-- 
2.47.0

On Thu, Dec 5, 2024 at 12:54 PM Fiona Behrens <me@kloenk.dev> wrote:
>
> Add the proc_macro crate from the rust sysroot to the
> rust-project.json file used by rust-analyzer. This allows
> rust-analyzer to autocomplete items from the proc_macro crate inside
> the macros crate.
>
> This also adds std and alloc only to be used by proc_macro and
> macros. This does not add the dependencies of those crates as this is
> sufficent for rust-analyzer to have a basic autocompletion support
> without having to worry about all the dependencies std usually needs.
> alloc is added, as e.g. std::vec just reexports from alloc, so that
> macros can use autocompletion for Vec and similar.

If you say that's sufficient, then I believe you.

> Signed-off-by: Fiona Behrens <me@kloenk.dev>

Reviewed-by: Alice Ryhl <aliceryhl@google.com>