Purge Python

[Ezrashaw]

Running the command: fd --extension py -E src/llvm-project gives a list of python files in rust-lang/rust:

compiler/rustc_codegen_gcc/tools/check_intrinsics_duplicates.py
compiler/rustc_codegen_gcc/tools/generate_intrinsics.py
library/core/src/unicode/printable.py
src/bootstrap/bootstrap.py
src/bootstrap/bootstrap_test.py
src/bootstrap/configure.py
src/ci/cpu-usage-over-time.py
src/ci/docker/host-x86_64/test-various/uefi_qemu_test/run.py
src/ci/docker/scripts/android-sdk-manager.py
src/ci/docker/scripts/fuchsia-test-runner.py
src/ci/github-actions/calculate-job-matrix.py
src/ci/scripts/upload-build-metrics.py
src/etc/dec2flt_table.py
src/etc/gdb_load_rust_pretty_printers.py
src/etc/gdb_lookup.py
src/etc/gdb_providers.py
src/etc/generate-deriving-span-tests.py
src/etc/generate-keyword-tests.py
src/etc/htmldocck.py
src/etc/lldb_batchmode.py
src/etc/lldb_lookup.py
src/etc/lldb_providers.py
src/etc/rust_types.py
src/tools/cargo/ci/generate.py
src/tools/cargo/publish.py
src/tools/clippy/util/versions.py
src/tools/miri/ci/scrape-targets.py
src/tools/miri/test-cargo-miri/run-test.py
src/tools/publish_toolstate.py
tests/debuginfo/auxiliary/dependency-with-embedded-visualizers.py
tests/debuginfo/embedded-visualizer-point.py
tests/debuginfo/embedded-visualizer.py
tests/run-make/debugger-visualizer-dep-info/my_gdb_script.py
tests/run-make/libtest-junit/validate_junit.py
x.py

While there will (probably) always be a need for a little bit of Python in bootstrap, we should aim to replace misc scripts that really should be Written In Rust. Especially relevant are files like src/etc/htmldocck.py which is the rustdoc UI test harness(!); we should rewrite this in Rust.

Extra points:

• I wonder if CI scripts do actually need to be Python?
• Longer term, I wonder if we can require a host installation of Rust (we just download one anyway) and use that for bootstrap?

[Ezrashaw]

cc @jyn514 am I crazy about getting rid of Python from bootstrap?

[jyn514]

I don't see the point in rewriting all this code. The main goal of #94829 is so we don't make people deal with python before they start working on the repo; but half the scripts you mentioned are for CI only. What do we get from rewriting them?

[Ezrashaw]

I guess maintainability in a way. I mean, why is compiletest not written in Python? It then makes sense to have the rustdoc part of it written in the same language, possibly src/etc/htmldocck.py could be rewritten and moved into compiletest itself. I'm not saying that this is important, just that it's something that should happen at some point.

[jyn514]

I don't think this is worth spending contributor time on. There are other ways people can get started contributing (https://rustc-dev-guide.rust-lang.org/#what-should-i-work-on).

[Ezrashaw]

I agree, I think it's just good to have this here as a long-term goal.

[compiler-errors]

It's probably worthwhile to first step back and characterize the existing python that we have. I think only once it's clear what python actually can be rewritten should we actually discuss whether it should be rewritten.

e.g. those gdb and llvm scripts can't be rewritten in rust afaict.

[Ezrashaw]

Yeah, perhaps CI scripts as well might not be rewritable?

I do think there is some low-hanging fruit here which could have tangible benefits.

[thomcc]

I have a rewrite of library/core/src/unicode/printable.py on another machine, moving it into the rest of the table generation code. I'll try to get it up when I'm more easily able to contribute.

[thomcc]

Assigning to myself to do this for the unicode tables because @jyn514 indicated it might be the only one that's worth doing (no strong opinions from me, although I don't like that one being python)