gh-128446: Skip Windows CI for configure/Makefile changes

Author: srinivasreddy

.github/workflows/build.yml

@@ -151,7 +151,7 @@ jobs:
       Windows
       ${{ fromJSON(matrix.free-threading) && '(free-threading)' || '' }}
     needs: check_source
-    if: fromJSON(needs.check_source.outputs.run_tests)
+    if: fromJSON(needs.check_source.outputs.run_tests) && fromJSON(needs.check_source.outputs.run-windows)
     strategy:
       fail-fast: false
       matrix:
@@ -182,7 +182,7 @@ jobs:
     name: >-  # ${{ '' } is a hack to nest jobs under the same sidebar category
       Windows MSI${{ '' }}
     needs: check_source
-    if: fromJSON(needs.check_source.outputs.run-win-msi)
+    if: fromJSON(needs.check_source.outputs.run-win-msi) && fromJSON(needs.check_source.outputs.run-windows)
     strategy:
       matrix:
         arch:

.github/workflows/reusable-change-detection.yml

@@ -36,6 +36,10 @@ on:  # yamllint disable-line rule:truthy
         description: Whether to run the MSI installer smoke tests
         value: >-  # bool
           ${{ jobs.compute-changes.outputs.run-win-msi || false }}
+      run-windows:
+        description: Whether to run the Windows CI
+        value: >-  # bool
+          ${{ jobs.compute-changes.outputs.run-windows || false }}
       run_hypothesis:
         description: Whether to run the Hypothesis tests
         value: >-  # bool
@@ -57,6 +61,7 @@ jobs:
       run-hypothesis: ${{ steps.check.outputs.run-hypothesis }}
       run-tests: ${{ steps.check.outputs.run-tests }}
       run-win-msi: ${{ steps.win-msi-changes.outputs.run-win-msi }}
+      run-windows: ${{ steps.check.outputs.run-windows }}
     steps:
     - run: >-
         echo '${{ github.event_name }}'
@@ -111,6 +116,23 @@ jobs:
           echo "Branch too old for CIFuzz tests; or no C files were changed"
           echo "run-cifuzz=false" >> "$GITHUB_OUTPUT"
         fi
+
+        # Check if changes are Windows-specific
+        if [ -z "$GITHUB_BASE_REF" ]; then
+          echo "run-windows=true" >> "$GITHUB_OUTPUT"
+        else
+          # Get changed files
+          CHANGED_FILES=$(git diff --name-only "origin/$GITHUB_BASE_REF..")
+
+          # Check if changes are only in configure/Makefile files
+          if echo "$CHANGED_FILES" | grep -qvE '^(configure.*|Makefile.*|.*\.m4)$'; then
+            # Other files changed, run Windows CI
+            echo "run-windows=true" >> "$GITHUB_OUTPUT"
+          else
+            # Only configure/Makefile files changed, skip Windows CI
+            echo "run-windows=false" >> "$GITHUB_OUTPUT"
+          fi
+        fi
     - name: Compute hash for config cache key
       id: config-hash
       run: |