Packages as namespaces part 1

[b-naber]

Part 1 of #152299

r? @petrochenkov

[rustbot]

HIR ty lowering was modified

cc @fmease

[rust-log-analyzer]

The job tidy failed! Check out the build log: (web) (plain enhanced) (plain)

Click to see the possible cause of the failure (guessed by this bot)

fmt: checked 6721 files
tidy check
tidy [rustdoc_json (src)]: `rustdoc-json-types` modified, checking format version
tidy: Skipping binary file check, read-only filesystem
tidy [style (compiler)]: /checkout/compiler/rustc_resolve/src/diagnostics.rs: too many lines (3003) (add `// ignore-tidy-filelength` to the file to suppress this error)
tidy [style (compiler)]: FAIL
removing old virtual environment
creating virtual environment at '/checkout/obj/build/venv' using 'python3.10' and 'venv'
creating virtual environment at '/checkout/obj/build/venv' using 'python3.10' and 'virtualenv'
Requirement already satisfied: pip in ./build/venv/lib/python3.10/site-packages (26.0.1)
linting python files
---
linting javascript files
Running eslint on rustdoc JS files
info: ES-Check: there were no ES version matching errors!  🎉
typechecking javascript files
tidy: The following check failed: style (compiler)
Command `/checkout/obj/build/x86_64-unknown-linux-gnu/stage1-tools-bin/rust-tidy --root-path=/checkout --cargo-path=/checkout/obj/build/x86_64-unknown-linux-gnu/stage0/bin/cargo --output-dir=/checkout/obj/build --concurrency=4 --npm-path=/node/bin/yarn --ci=true --extra-checks=py,cpp,js,spellcheck` failed with exit code 1
Created at: src/bootstrap/src/core/build_steps/tool.rs:1612:23
Executed at: src/bootstrap/src/core/build_steps/test.rs:1382:29

Command has failed. Rerun with -v to see more details.
Bootstrap failed while executing `test src/tools/tidy tidyselftest --extra-checks=py,cpp,js,spellcheck`
Build completed unsuccessfully in 0:02:48
  local time: Mon Mar  2 23:01:49 UTC 2026
  network time: Mon, 02 Mar 2026 23:01:49 GMT
##[error]Process completed with exit code 1.