Include cxxbridge-cmd in Cargo.lock, check version consistency (#3712)

This adds cxxbridge-cmd to Cargo.lock per
https://github.com/dtolnay/cxx/issues/1407#issuecomment-2509136343

It adds an MSRV to `src/taskchampion-cpp/Cargo.toml` so that the
version of `Cargo.lock` is stil compatible with the MSRV.

It additionally adds a check of the Cargo metadata for all of the cxx*
versions agreeing, and for the MSRV's agreeing.

.github/workflows/checks.yml

@@ -64,3 +64,19 @@ jobs:
         with:
           command: fmt
           args: --all -- --check
+
+  cargo-metadata:
+    runs-on: ubuntu-latest
+    name: "Cargo Metadata"
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: actions-rs/toolchain@v1
+        with:
+          profile: minimal
+          components: rustfmt
+          toolchain: stable
+          override: true
+
+      - name: "Check metadata"
+        run: ".github/workflows/metadata-check.sh"

.github/workflows/metadata-check.sh

@@ -0,0 +1,73 @@
+#! /bin/bash
+
+# Check the 'cargo metadata' for various requirements
+
+set -e
+
+META=$(mktemp)
+trap 'rm -rf -- "${META}"' EXIT
+
+cargo metadata --locked --format-version 1 > "${META}"
+
+get_version() {
+  local package="${1}"
+  jq -r '.packages[] | select(.name == "'"${package}"'") | .version' "${META}"
+}
+
+get_msrv() {
+  local package="${1}"
+  jq -r '.packages[] | select(.name == "'"${package}"'") | .rust_version' "${META}"
+}
+
+# check that the cxx packages all have the same version
+check_cxx_versions() {
+  local cxx_version=$(get_version "cxx")
+  local cxx_build_version=$(get_version "cxx-build")
+  local cxxbridge_cmd_version=$(get_version "cxx-build")
+  local cxxbridge_flags_version=$(get_version "cxxbridge-flags")
+  local cxxbridge_macro_version=$(get_version "cxxbridge-macro")
+
+  ok=true
+  echo "Found cxx version ${cxx_version}"
+  if [ "${cxx_version}" != "${cxx_build_version}" ]; then
+    echo "Found differing cxx-build version ${cxx_build_version}"
+    ok = false
+  fi
+  if [ "${cxx_version}" != "${cxxbridge_cmd_version}" ]; then
+    echo "Found differing cxxbridge-cmd version ${cxxbridge_cmd_version}"
+    ok = false
+  fi
+  if [ "${cxx_version}" != "${cxxbridge_flags_version}" ]; then
+    echo "Found differing cxxbridge-flags version ${cxxbridge_flags_version}"
+    ok = false
+  fi
+  if [ "${cxx_version}" != "${cxxbridge_macro_version}" ]; then
+    echo "Found differing cxxbridge-macro version ${cxxbridge_macro_version}"
+    ok = false
+  fi
+
+  if ! $ok; then
+    echo "All cxx packages must be at the same version. Fix this in src/taskchampion-cpp/Cargo.toml."
+    exit 1
+  else
+    echo "✓ All cxx packages are at the same version."
+  fi
+}
+
+check_msrv() {
+  local taskchampion_msrv=$(get_msrv taskchampion)
+  local taskchampion_lib_msrv=$(get_msrv taskchampion-lib)
+
+  echo "Found taskchampion MSRV ${taskchampion_msrv}"
+  echo "Found taskchampion-lib MSRV ${taskchampion_lib_msrv}"
+
+  if [ "${taskchampion_msrv}" != "${taskchampion_lib_msrv}" ]; then
+    echo "Those MSRVs should be the same (or taskchampion-lib should be greater, in which case adjust this script)"
+    exit 1
+  else
+    echo "✓ MSRVs are at the same version."
+  fi
+}
+
+check_cxx_versions
+check_msrv

.github/workflows/tests.yaml

@@ -118,6 +118,7 @@ jobs:
           # If this version is old enough to cause errors, or older than the
           # TaskChampion MSRV, bump it to the MSRV of the currently-required
           # TaskChampion package; if necessary, bump that version as well.
+          # This should match the MSRV in `src/taskchampion-cpp/Cargo.toml`.
           toolchain: "1.73.0" # MSRV
           override: true