Starting around nightly 2026-01-22 (rustc 1.95.0-nightly), the Rust distribution ships stdlib .rlib files as ~440-byte metadata stubs, with full metadata in separate .rmeta files alongside them. Previously, .rlib files contained the full metadata (~47MB each) and no .rmeta files existed.

The _build_file_for_stdlib_template glob only includes *.rlib and not *.rmeta, so the metadata files are excluded from the sysroot, causing:

error[E0786]: found invalid metadata files for crate `core`
  = note: only metadata stub found for rlib dependency `core`

Cargo builds with the same nightly work fine, confirming the issue is specific to how rules_rust assembles the sysroot.

Fix

Add *.rmeta to the glob:

     srcs = glob(
         [
             "lib/rustlib/{target_triple}/lib/*.rlib",
+            "lib/rustlib/{target_triple}/lib/*.rmeta",
             "lib/rustlib/{target_triple}/lib/*{dylib_ext}*",

_symlink_sysroot_tree symlinks all files from the stdlib target, so the new files will be picked up transitively. _rust_stdlib_filegroup_impl iterates over .rlib files specifically for ordering, but that should still work since .rlib files are still present.

Versions

• rules_rust: 0.68.1
• Rust: nightly-2026-01-22 (rustc 1.95.0-nightly)
• Bazel: 8.x
• Platforms confirmed: macOS aarch64, macOS x86_64 (cross-compile)