Speed up submodule checkouts for the tidy job

Author: Kobzol

src/ci/github-actions/jobs.yml

@@ -128,6 +128,10 @@ pr:
     <<: *job-linux-4c
   - name: mingw-check-tidy
     continue_on_error: true
+    env:
+      # These submodules are expensive to checkout, and they should not be needed for
+      # tidy. This speeds up the PR CI job by ~2 minutes.
+      SKIP_SUBMODULES: src/llvm-project,src/gcc
     <<: *job-linux-4c
   - name: x86_64-gnu-llvm-19
     env:

src/ci/scripts/checkout-submodules.sh

@@ -37,7 +37,7 @@ function fetch_github_commit_archive {
 }
 
 #included="src/llvm-project src/doc/book src/doc/rust-by-example"
-included=""
+included="src/llvm-project src/gcc"
 modules="$(git config --file .gitmodules --get-regexp '\.path$' | cut -d' ' -f2)"
 modules=($modules)
 use_git=""
@@ -55,7 +55,11 @@ for i in ${!modules[@]}; do
         bg_pids[${i}]=$!
         continue
     else
+      # Submodule paths contained in SKIP_SUBMODULES (comma-separated list) will not be
+      # checked out.
+      if [ -z "${SKIP_SUBMODULES:-}" ] || [[ ! ",$SKIP_SUBMODULES," = *",$module,"* ]]; then
         use_git="$use_git $module"
+      fi
     fi
 done
 retry sh -c "git submodule deinit -f $use_git && \