Actions: Fix handling of paths-ignore in autobuild scripts

Always concatenate the default filters with the user-provided filters.
This ensures that when `paths-ignore` is provided,
we begin with the default path inclusions,
not all YAML files.
This makes the `paths-ignore-only` integration test variant
under `filters` pass.

The handling of `paths` is unchanged:
if provided, this overrides the default filters.

Author: adityasharad

actions/extractor/tools/autobuild-impl.ps1

@@ -1,21 +1,28 @@
-if (($null -ne $env:LGTM_INDEX_INCLUDE) -or ($null -ne $env:LGTM_INDEX_EXCLUDE) -or ($null -ne $env:LGTM_INDEX_FILTERS)) {
-    Write-Output 'Path filters set. Passing them through to the JavaScript extractor.' 
-} else {
-    Write-Output 'No path filters set. Using the default filters.'
-    # Note: We're adding the `reusable_workflows` subdirectories to proactively
-    # record workflows that were called cross-repo, check them out locally,
-    # and enable an interprocedural analysis across the workflow files.
-    # These workflows follow the convention `.github/reusable_workflows/<nwo>/*.ya?ml`
-    $DefaultPathFilters = @(
-        'exclude:**/*',
-        'include:.github/workflows/*.yml',
-        'include:.github/workflows/*.yaml',
-        'include:.github/reusable_workflows/**/*.yml',
-        'include:.github/reusable_workflows/**/*.yaml',
-        'include:**/action.yml',
-        'include:**/action.yaml'
-    )
+# Note: We're adding the `reusable_workflows` subdirectories to proactively
+# record workflows that were called cross-repo, check them out locally,
+# and enable an interprocedural analysis across the workflow files.
+# These workflows follow the convention `.github/reusable_workflows/<nwo>/*.ya?ml`
+$DefaultPathFilters = @(
+    'exclude:**/*',
+    'include:.github/workflows/*.yml',
+    'include:.github/workflows/*.yaml',
+    'include:.github/reusable_workflows/**/*.yml',
+    'include:.github/reusable_workflows/**/*.yaml',
+    'include:**/action.yml',
+    'include:**/action.yaml'
+)
 
+if ($null -ne $env:LGTM_INDEX_FILTERS) {
+    Write-Output 'LGTM_INDEX_FILTERS set. Using the default filters together with the user-provided filters, and passing through to the JavaScript extractor.'
+    # Begin with the default path inclusions only,
+    # followed by the user-provided filters.
+    # If the user provided `paths`, those patterns override the default inclusions
+    # (because `LGTM_INDEX_FILTERS` will begin with `exclude:**/*`).
+    # If the user provided `paths-ignore`, those patterns are excluded.
+    $PathFilters = ($DefaultPathFilters -join "`n") + "`n" + $env:LGTM_INDEX_FILTERS
+    $env:LGTM_INDEX_FILTERS = $PathFilters
+} else {
+    Write-Output 'LGTM_INDEX_FILTERS not set. Using the default filters, and passing through to the JavaScript extractor.'
     $env:LGTM_INDEX_FILTERS = $DefaultPathFilters -join "`n"
 }
 

actions/extractor/tools/autobuild.sh

@@ -17,10 +17,22 @@ include:**/action.yaml
 END
 )
 
-if [ -n "${LGTM_INDEX_INCLUDE:-}" ] || [ -n "${LGTM_INDEX_EXCLUDE:-}" ] || [ -n "${LGTM_INDEX_FILTERS:-}" ] ; then
-    echo "Path filters set. Passing them through to the JavaScript extractor."
+if [ -n "${LGTM_INDEX_FILTERS:-}" ]; then
+    echo "LGTM_INDEX_FILTERS set. Using the default filters together with the user-provided filters, and passing through to the JavaScript extractor."
+    # Begin with the default path inclusions only,
+    # followed by the user-provided filters.
+    # If the user provided `paths`, those patterns override the default inclusions
+    # (because `LGTM_INDEX_FILTERS` will begin with `exclude:**/*`).
+    # If the user provided `paths-ignore`, those patterns are excluded.
+    PATH_FILTERS="$(cat << END
+${DEFAULT_PATH_FILTERS}
+${LGTM_INDEX_FILTERS}
+END
+)"
+    LGTM_INDEX_FILTERS="${PATH_FILTERS}"
+    export LGTM_INDEX_FILTERS
 else
-    echo "No path filters set. Using the default filters."
+    echo "LGTM_INDEX_FILTERS not set. Using the default filters, and passing through to the JavaScript extractor."
     LGTM_INDEX_FILTERS="${DEFAULT_PATH_FILTERS}"
     export LGTM_INDEX_FILTERS
 fi