Install rustc-dev

Author: lnicola

.github/workflows/ci.yaml

@@ -48,6 +48,7 @@ jobs:
       CC: deny_c
       RUST_CHANNEL: "${{ needs.changes.outputs.proc_macros == 'true' && 'nightly' || 'stable' }}"
       USE_SYSROOT_ABI: "${{ needs.changes.outputs.proc_macros == 'true' && '--features sysroot-abi' || '' }}"
+      RUSTUP_RUSTC_DEV: "${{ needs.changes.outputs.proc_macros == 'true' && 'rustc-dev' || '' }}"
 
     strategy:
       fail-fast: false
@@ -63,7 +64,7 @@ jobs:
       - name: Install Rust toolchain
         run: |
           rustup update --no-self-update ${{ env.RUST_CHANNEL }}
-          rustup component add --toolchain ${{ env.RUST_CHANNEL }} rustfmt rust-src
+          rustup component add --toolchain ${{ env.RUST_CHANNEL }} rustfmt rust-src ${{ env.RUSTUP_RUSTC_DEV }}
           rustup default ${{ env.RUST_CHANNEL }}
 
       - name: Cache Dependencies