Avoid non reproducible cache generation at codcov (#10926)

Author: oech3

.github/workflows/CICD.yml

@@ -1116,26 +1116,22 @@ jobs:
       SCCACHE_GHA_ENABLED: "true"
       RUSTC_WRAPPER: "sccache"
       CARGO_INCREMENTAL: 0
+      RUSTC_BOOTSTRAP: 1
     strategy:
       fail-fast: false
       matrix:
         job:
-          - { os: ubuntu-latest  , features: unix, toolchain: nightly }
+          - { os: ubuntu-latest  , features: unix }
           # FIXME: Re-enable macos code coverage
-          # - { os: macos-latest   , features: macos, toolchain: nightly }
+          # - { os: macos-latest   , features: macos }
           # FIXME: Re-enable Code Coverage on windows, which currently fails due to "profiler_builtins". See #6686.
-          # - { os: windows-latest , features: windows, toolchain: nightly-x86_64-pc-windows-gnu }
+          # - { os: windows-latest , features: windows, toolchain: stable-x86_64-pc-windows-gnu }
     steps:
     - uses: actions/checkout@v6
-    - uses: dtolnay/rust-toolchain@master
-      with:
-        toolchain: ${{ matrix.job.toolchain }}
-        components: rustfmt
     - uses: taiki-e/install-action@v2
       with:
         tool: nextest,grcov@0.8.24
     - uses: Swatinem/rust-cache@v2
-
     - name: Run sccache-cache
       uses: mozilla-actions/sccache-action@v0.0.9
 
@@ -1149,9 +1145,6 @@ jobs:
         ## VARs setup
         outputs() { step_id="${{ github.action }}"; for var in "$@" ; do echo steps.${step_id}.outputs.${var}="${!var}"; echo "${var}=${!var}" >> $GITHUB_OUTPUT; done; }
 
-        # toolchain
-        TOOLCHAIN="nightly" ## default to "nightly" toolchain (required for certain required unstable compiler flags) ## !maint: refactor when stable channel has needed support
-
         # * specify gnu-type TOOLCHAIN for windows; `grcov` requires gnu-style code coverage data files
         case ${{ matrix.job.os }} in windows-*) TOOLCHAIN="$TOOLCHAIN-x86_64-pc-windows-gnu" ;; esac;
 

util/build-run-test-coverage-linux.sh

@@ -41,10 +41,10 @@ REPO_main_dir="$(dirname -- "${ME_dir}")"
 FEATURES_OPTION=${FEATURES_OPTION:-"--features=feat_os_unix"}
 COVERAGE_DIR=${COVERAGE_DIR:-"${REPO_main_dir}/coverage"}
 
-# Find llvm-profdata in the nightly toolchain (which is used for coverage builds)
-LLVM_PROFDATA="$(find "$(RUSTUP_TOOLCHAIN=nightly-gnu rustc --print sysroot)" -name llvm-profdata)"
+# Find llvm-profdata (which is used for coverage builds)
+LLVM_PROFDATA="$(find "$(rustc --print sysroot)" -name llvm-profdata)"
 if [ -z "${LLVM_PROFDATA}" ]; then
-    echo "Error: llvm-profdata not found. Install it with: rustup +nightly-gnu component add llvm-tools"
+    echo "Error: llvm-profdata not found. Install it with: rustup component add llvm-tools"
     exit 1
 fi
 
@@ -60,10 +60,10 @@ rm -rf "${REPORT_DIR}" && mkdir -p "${REPORT_DIR}"
 #shellcheck disable=SC2086
 UTIL_LIST=$("${ME_dir}"/show-utils.sh ${FEATURES_OPTION})
 
+export RUSTC_BOOTSTRAP=1
 export CARGO_INCREMENTAL=0
 export RUSTFLAGS="-Cinstrument-coverage -Ccodegen-units=1 -Copt-level=0 -Clink-dead-code -Coverflow-checks=off -Zpanic_abort_tests -Cpanic=abort"
 export RUSTDOCFLAGS="-Cpanic=abort"
-export RUSTUP_TOOLCHAIN="nightly-gnu"
 export LLVM_PROFILE_FILE="${PROFRAW_DIR}/coverage-%4m.profraw"
 
 # Disable expanded command printing for the rest of the program