Rust/PyO3 proof of concept

.circleci/config.yml

@@ -126,6 +126,12 @@ jobs:
             - -pkg1-v20220303-{{ checksum "Makefile.envs" }}
             - -pkg1-v20220303
 
+      - run:
+          name: install rust
+          command: |
+            wget https://sh.rustup.rs -O /rustup.sh
+            sh /rustup.sh -y
+
       - run:
           name: build packages
           no_output_timeout: 30m

emsdk/patches/0001-fix-up-rust-linker-errors.patch

@@ -0,0 +1,61 @@
+From db60466a899dab0c9d008b7ab27f4d4c11fe60da Mon Sep 17 00:00:00 2001
+From: Hood Chatham <roberthoodchatham@gmail.com>
+Date: Thu, 6 Jan 2022 09:40:39 -0800
+Subject: [PATCH] fix up rust linker errors
+
+This fixes a few problems that come up when linking rust programs:
+1. Rust .rlib archives contain an extra metadata file called lib.rmeta. The
+   linker is not happy about these archives. Modifying the archive in place
+   breaks Cargo. Instead, copy the archive to a temp file, remove lib.rmeta
+   from the temp file, and link the modified copy.
+2. We need to run ranlib on the archive.
+3. libcompiler_builtins.rlib contains invalid wasm. I'm not sure why. Nothing
+   too bad *seems* to go wrong if we just drop it.
+---
+ tools/building.py | 30 ++++++++++++++++++++++++++++--
+ 1 file changed, 28 insertions(+), 2 deletions(-)
+
+diff --git a/tools/building.py b/tools/building.py
+index 512561c69..8b534e548 100644
+--- a/tools/building.py
++++ b/tools/building.py
+@@ -464,8 +464,34 @@ def link_lld(args, target, external_symbols=None):
+   if '--relocatable' not in args and '-r' not in args:
+     cmd += lld_flags_for_executable(external_symbols)
+
+-  cmd = get_command_with_possible_response_file(cmd)
+-  check_call(cmd)
++  if "EMSCRIPTEN_LINKING_RUST" in os.environ:
++    from tempfile import mkstemp
++    from pathlib import Path
++    tempfiles = []
++    new_cmd = []
++    try:
++      for arg in cmd:
++        if arg == "-lc":
++          continue
++        if not arg.endswith(".rlib"):
++          new_cmd.append(arg)
++          continue
++        fd, temp_path = mkstemp()
++        shutil.copy2(arg, temp_path)
++        tempfiles.append(Path(temp_path))
++        subprocess.call(["ar", "-d", temp_path, "lib.rmeta"])
++        subprocess.call(["emranlib", temp_path])
++        new_cmd.append(temp_path)
++      cmd = new_cmd
++      cmd = get_command_with_possible_response_file(cmd)
++      check_call(cmd)
++    finally:
++      for file in tempfiles:
++        file.unlink()
++  else:
++    cmd = get_command_with_possible_response_file(cmd)
++    check_call(cmd)
++
+
+
+ def link_bitcode(args, target, force_archive_contents=False):
+-- 
+2.25.1
+

packages/pyo3_samples/meta.yaml

@@ -0,0 +1,29 @@
+package:
+  name: pyo3_samples
+  version: 0.1.0
+source:
+  # url: https://github.com/hoodmane/pyo3_samples/tarball/main
+  # sha256: 5a402fc5323365cd2fce3379a7a619e6dba28083bf7eed1ec554820c1551dce2
+  path: src
+build:
+  sharedlibrary: true
+  script: |
+    source $HOME/.cargo/env
+    rustup update nightly
+    rustup component add rust-src --toolchain nightly-x86_64-unknown-linux-gnu
+    export EMSCRIPTEN_LINKING_RUST=1
+    export RUSTFLAGS="\
+      -C relocation-model=pic\
+      -C target-feature=+mutable-globals\
+      -C link-arg=-s\
+      -C link-arg=SIDE_MODULE=1\
+    "
+    export PYO3_CONFIG_FILE=$PYODIDE_ROOT/packages/pyo3_samples/pyo3_config.ini
+    cargo +nightly -Z build-std build --target=wasm32-unknown-emscripten --release
+    echo "hi?"
+    mkdir -p dist
+    cp target/wasm32-unknown-emscripten/release/pyo3_samples.wasm dist/pyo3_samples.so
+
+test:
+  imports:
+    - pyo3_samples

packages/pyo3_samples/pyo3_config.ini

@@ -0,0 +1,9 @@
+implementation=CPython
+version=3.9
+shared=true
+abi3=false
+lib_name=python3.9
+lib_dir=/home/hood/Documents/programming/pyodide/cpython/installs/python-3.9.5/lib/
+pointer_width=32
+build_flags=WITH_THREAD
+suppress_build_script_link_lines=false