Make sure we have a recent enough rustc to build packages

.github/workflows/build-packages.yml

@@ -183,6 +183,19 @@ jobs:
       # Checkout here so we can easily use custom actions
       - uses: actions/checkout@v4
 
+      # We need a more recent rustc
+      - name: Install a more recent `rustc`
+        if: ${{ inputs.source == 'src' }}
+        uses: actions-rust-lang/setup-rust-toolchain@v1
+
+      - name: Set rust environment variables
+        if: ${{ inputs.source == 'src' }}
+        run: |
+          CARGO_HOME=${CARGO_HOME:-${HOME}/.cargo}
+          export CARGO_HOME
+          echo "CARGO_HOME=${CARGO_HOME}" | tee -a "${GITHUB_ENV}"
+          echo "${CARGO_HOME}/bin" | tee -a "${GITHUB_PATH}"
+
       # Checkout here for the build process
       - name: Checkout in build directory
         uses: actions/checkout@v4

tools/pkg/build.py

@@ -8,6 +8,7 @@ from __future__ import annotations
 import json
 import logging
 import os
+import os.path
 import pathlib
 import shutil
 import tarfile
@@ -90,6 +91,20 @@ def debian(
             os.environ[key] = value
             env_args.extend(["-e", key])
 
+        cargo_home = os.environ.get("CARGO_HOME")
+        user_cargo_bin = os.path.expanduser("~/.cargo/bin")
+        if os.path.exists(user_cargo_bin):
+            ctx.info(
+                f"The path '{user_cargo_bin}' exists so adding --prepend-path={user_cargo_bin}"
+            )
+            env_args.append(f"--prepend-path={user_cargo_bin}")
+        elif cargo_home is not None:
+            cargo_home_bin = os.path.join(cargo_home, "bin")
+            ctx.info(
+                f"The 'CARGO_HOME' environment variable is set, so adding --prepend-path={cargo_home_bin}"
+            )
+            env_args.append(f"--prepend-path={cargo_home_bin}")
+
     env = os.environ.copy()
     env["PIP_CONSTRAINT"] = str(
         tools.utils.REPO_ROOT / "requirements" / "constraints.txt"