OpenAI Codex up to date rust environment, and download packages.

rust_env.sh

#!/usr/bin/env bash

set -euo pipefail

CARGO_TOML="Cargo.toml"

PROFILE_CHUNK=$(cat <<'EOF'

[profile.dev]
opt-level = 0
debug = 0
incremental = true
codegen-units = 256
panic = "unwind"
lto = false
overflow-checks = false

[profile.test]
inherits = "dev"
EOF
)

# Check if profile.dev already exists
if grep -q "^\[profile\.dev\]" "$CARGO_TOML"; then
    echo "Cargo.toml already contains [profile.dev], skipping patch."
else
    echo "Appending dev/test profiles to $CARGO_TOML"
    echo "$PROFILE_CHUNK" >> "$CARGO_TOML"
fi

rustup update
cargo fetch
cargo install --path .  --profile dev

The 'dev' profile is an attempt to faster compilation.