Use nightly for miri (#3268)

* miri nightly

* actually add miri

* ??

* clp cache new

.github/workflows/build_and_test.yml

@@ -104,11 +104,15 @@ jobs:
     runs-on: ubuntu-24.04
     if: contains( github.event.pull_request.labels.*.name, 'pre-release')
     steps:
-      - name: Add miri
-        run: rustup toolchain install --component miri --allow-downgrade
       - uses: actions/checkout@v4
       - uses: ./.github/workflows/ubuntu-prepare
+        with:
+          use_nightly: 'true'
+      - name: Add miri
+        run: rustup +nightly component add miri
       - uses: Swatinem/rust-cache@v2
+        with:
+          shared-key: ubuntu-miri
       # --- miri undefined behavior test --
       - name: Run miri tests
         run: RUST_BACKTRACE=1 MIRIFLAGS="-Zmiri-disable-isolation" cargo miri test
@@ -145,7 +149,8 @@ jobs:
       - uses: actions/checkout@v4
       - uses: ./.github/workflows/ubuntu-prepare
       - uses: Swatinem/rust-cache@v2
-        with: { shared-key: "ubuntu" }
+        with:
+          shared-key: "ubuntu-clippy"
       - name: Run clippy
         run: LLVM_CONFIG=llvm-config-${{env.MAIN_LLVM_VERSION}} ./scripts/clippy.sh
     # --- test embedding the libafl_libfuzzer_runtime library

.github/workflows/ubuntu-prepare/action.yml

@@ -1,25 +1,51 @@
 name: Setup Rust Environment
-description: Sets up the Rust environment for the CI workflow
+description: Sets up the Rust environment for the CI workflow and optionally installs nightly
+
+# ---------- new section ----------
+inputs:
+  use_nightly:
+    description: "If true, install the Rust nightly toolchain instead of stable"
+    required: false
+    default: "false"
+# ---------------------------------
+
 runs:
   using: composite
   steps:
-    - name: Uninstall all currently installed rust
+    - name: Uninstall all currently installed Rust
       shell: bash
       run: |
         sudo apt purge -y 'cargo*' 'rust*'
+
     - name: Install and cache deps
       shell: bash
       run: |
         sudo apt-get update
-        sudo apt-get install -y curl lsb-release wget software-properties-common gnupg shellcheck pax-utils libsqlite3-dev libpixman-1-dev libc6-dev gcc g++ build-essential libglib2.0-dev
+        sudo apt-get install -y \
-    - uses: dtolnay/rust-toolchain@stable
+          curl lsb-release wget software-properties-common gnupg shellcheck pax-utils \
+          libsqlite3-dev libpixman-1-dev libc6-dev gcc g++ build-essential libglib2.0-dev
+
+    # ---------- toolchain selection ----------
+    - name: Install Rust (stable)
+      if: ${{ inputs.use_nightly == 'false' }}
+      uses: dtolnay/rust-toolchain@stable
       with:
         components: clippy, rustfmt
-    - name: install just
+
+    - name: Install Rust (nightly)
+      if: ${{ inputs.use_nightly == 'true' }}
+      uses: dtolnay/rust-toolchain@nightly
+      with:
+        components: clippy, rustfmt
+    # -----------------------------------------
+
+    - name: Install just
       uses: extractions/setup-just@v2
       with:
         just-version: '1.40.0'
+
     - uses: taiki-e/install-action@cargo-hack
+
     - name: Install LLVM
       shell: bash
       run: |
@@ -27,6 +53,7 @@ runs:
         chmod +x llvm.sh
         sudo ./llvm.sh ${{ env.MAIN_LLVM_VERSION }} all
         sudo update-alternatives --install /usr/bin/clang clang /usr/bin/clang-${{ env.MAIN_LLVM_VERSION }} 200
-    - name: Symlink Headers
+
+    - name: Symlink headers
       shell: bash
       run: sudo ln -s /usr/include/asm-generic /usr/include/asm