ci: capture compiler warnings from all CI matrix builds

Enable self-hosted runners to collect warnings from nvfortran (Phoenix),
Cray ftn (Frontier), and AMD flang (Frontier AMD). Rebuild MFC targets
with -j1 in staging dirs to capture warnings with file/line context.
Skip dependency dirs (fftw, hdf5, silo, lapack).
Use find instead of ls to avoid ANSI color codes in filenames.
This CI change is temporary and will be reverted before merge.

Author: sbryngelson

.github/workflows/common/collect-warnings.sh

@@ -0,0 +1,28 @@
+#!/bin/bash
+# Rebuild each target with -j1 to capture compiler warnings with file/line info.
+# Runs inside a SLURM job after the main build completes.
+
+set -uo pipefail
+
+echo "=== Collecting compiler warnings ==="
+
+for staging_dir in build/staging/*/; do
+    [ -f "$staging_dir/CMakeCache.txt" ] || continue
+    # Skip dependency builds
+    case "$staging_dir" in *fftw*|*hdf5*|*silo*|*lapack*) continue ;; esac
+    target_dir=$(find "$staging_dir/CMakeFiles/" -maxdepth 1 -name '*.dir' -type d 2>/dev/null | head -1)
+    [ -z "$target_dir" ] && continue
+    target=$(basename "$target_dir" .dir)
+
+    echo ""
+    echo "=== Target: $target ==="
+    cd "$staging_dir"
+    # Touch all generated .f90 to force recompile
+    find fypp/ -name '*.f90' -exec touch {} + 2>/dev/null
+    # Rebuild single-threaded to get clean warning output with file/line context
+    make "$target" -j1 2>&1 | grep -E "Warning:|warning:" -B3 || echo "(no warnings)"
+    cd - > /dev/null
+done
+
+echo ""
+echo "=== Done collecting warnings ==="

.github/workflows/test.yml

@@ -261,6 +261,35 @@ jobs:
           TEST_ALL: ${{ matrix.mpi == 'mpi' && '--test-all' || '' }}
           PRECISION: ${{ matrix.precision != '' && format('--{0}', matrix.precision) || '' }}
 
+      - name: Collect Compiler Warnings
+        if: always()
+        run: |
+          echo "::group::Compiler warnings"
+          for staging_dir in build/staging/*/; do
+            [ -f "$staging_dir/CMakeCache.txt" ] || continue
+            # Skip dependency builds (fftw, hdf5, silo, lapack)
+            case "$staging_dir" in *fftw*|*hdf5*|*silo*|*lapack*) continue ;; esac
+            target=$(find "$staging_dir/CMakeFiles/" -maxdepth 1 -name '*.dir' -type d 2>/dev/null | head -1 | xargs basename 2>/dev/null | sed 's/\.dir//')
+            [ -z "$target" ] && continue
+            echo "=== Rebuilding $target for warnings ==="
+            cd "$staging_dir"
+            find fypp/ -name '*.f90' -exec touch {} + 2>/dev/null
+            make "$target" -j1 2>&1 | grep -E "Warning:|warning:" -B2 > /tmp/warnings_${target}.txt 2>&1 || true
+            count=$(grep -c "Warning:\|warning:" /tmp/warnings_${target}.txt 2>/dev/null || echo 0)
+            echo "--- $target: $count warnings ---"
+            cat /tmp/warnings_${target}.txt
+            cd - > /dev/null
+          done
+          echo "::endgroup::"
+
+      - name: Upload Warning Reports
+        if: always()
+        uses: actions/upload-artifact@v4
+        with:
+          name: warnings-${{ matrix.os }}-${{ matrix.mpi }}-${{ matrix.debug }}-intel-${{ matrix.intel }}
+          path: /tmp/warnings_*.txt
+          if-no-files-found: ignore
+
       - name: Test
         run:  |
           /bin/bash mfc.sh test -v --max-attempts 3 -j $(nproc) $ONLY_CHANGES $TEST_ALL $TEST_PCT
@@ -278,8 +307,7 @@ jobs:
       needs.file-changes.result == 'success' &&
       (needs.rebuild-cache.result == 'success' || needs.rebuild-cache.result == 'skipped') &&
       github.repository == 'MFlowCode/MFC' &&
-      needs.file-changes.outputs.checkall == 'true' &&
-      github.event.pull_request.draft != true
+      needs.file-changes.outputs.checkall == 'true'
     # Frontier CCE compiler is periodically broken by toolchain updates (e.g.
     # cpe/25.03 introduced an IPA SIGSEGV in CCE 19.0.0). Allow Frontier to
     # fail without blocking PR merges; Phoenix remains a hard gate.
@@ -408,6 +436,20 @@ jobs:
       - name: Build
         run:  bash .github/scripts/submit-slurm-job.sh .github/workflows/common/build.sh ${{ matrix.device }} ${{ matrix.interface }} ${{ matrix.cluster }} ${{ matrix.shard }}
 
+      - name: Collect Compiler Warnings
+        if: always()
+        run: |
+          bash .github/scripts/submit-slurm-job.sh .github/workflows/common/collect-warnings.sh ${{ matrix.device }} ${{ matrix.interface }} ${{ matrix.cluster }} ${{ matrix.shard }} || true
+
+      - name: Print Warnings
+        if: always()
+        run: |
+          echo "::group::Compiler warnings (${{ matrix.cluster_name }} ${{ matrix.device }}-${{ matrix.interface }})"
+          for f in collect-warnings-*.out; do
+            [ -f "$f" ] && cat "$f"
+          done
+          echo "::endgroup::"
+
       - name: Test
         run:  bash .github/scripts/submit-slurm-job.sh .github/workflows/common/test.sh ${{ matrix.device }} ${{ matrix.interface }} ${{ matrix.cluster }} ${{ matrix.shard }}