Fix MLIR lit test configuration for multi-config generators and enable C++ tests for MLIR changes

.github/workflows/ci.yml

@@ -19,7 +19,7 @@ jobs:
   cpp-tests-ubuntu:
     name: 🇨‌ Test 🐧
     needs: change-detection
-    if: fromJSON(needs.change-detection.outputs.run-cpp-tests) && !contains(github.event.pull_request.labels.*.name, 'extensive-cpp-ci')
+    if: (fromJSON(needs.change-detection.outputs.run-cpp-tests) || fromJSON(needs.change-detection.outputs.run-mlir)) && !contains(github.event.pull_request.labels.*.name, 'extensive-cpp-ci')
     strategy:
       fail-fast: false
       matrix:
@@ -39,7 +39,7 @@ jobs:
   cpp-tests-macos:
     name: 🇨‌ Test 🍎
     needs: change-detection
-    if: fromJSON(needs.change-detection.outputs.run-cpp-tests) && !contains(github.event.pull_request.labels.*.name, 'extensive-cpp-ci')
+    if: (fromJSON(needs.change-detection.outputs.run-cpp-tests) || fromJSON(needs.change-detection.outputs.run-mlir)) && !contains(github.event.pull_request.labels.*.name, 'extensive-cpp-ci')
     strategy:
       fail-fast: false
       matrix:
@@ -60,7 +60,7 @@ jobs:
   cpp-tests-windows:
     name: 🇨‌ Test 🏁
     needs: change-detection
-    if: fromJSON(needs.change-detection.outputs.run-cpp-tests) && !contains(github.event.pull_request.labels.*.name, 'extensive-cpp-ci')
+    if: (fromJSON(needs.change-detection.outputs.run-cpp-tests) || fromJSON(needs.change-detection.outputs.run-mlir)) && !contains(github.event.pull_request.labels.*.name, 'extensive-cpp-ci')
     strategy:
       fail-fast: false
       matrix:
@@ -81,7 +81,7 @@ jobs:
   cpp-tests-extensive-ubuntu:
     name: 🇨‌ Test (Extensive) 🐧
     needs: change-detection
-    if: fromJSON(needs.change-detection.outputs.run-cpp-tests) && github.event_name == 'pull_request' && contains(github.event.pull_request.labels.*.name, 'extensive-cpp-ci')
+    if: (fromJSON(needs.change-detection.outputs.run-cpp-tests) || fromJSON(needs.change-detection.outputs.run-mlir)) && github.event_name == 'pull_request' && contains(github.event.pull_request.labels.*.name, 'extensive-cpp-ci')
     strategy:
       fail-fast: false
       matrix:
@@ -98,7 +98,7 @@ jobs:
   cpp-tests-extensive-macos:
     name: 🇨‌ Test (Extensive) 🍎
     needs: change-detection
-    if: fromJSON(needs.change-detection.outputs.run-cpp-tests) && github.event_name == 'pull_request' && contains(github.event.pull_request.labels.*.name, 'extensive-cpp-ci')
+    if: (fromJSON(needs.change-detection.outputs.run-cpp-tests) || fromJSON(needs.change-detection.outputs.run-mlir)) && github.event_name == 'pull_request' && contains(github.event.pull_request.labels.*.name, 'extensive-cpp-ci')
     strategy:
       fail-fast: false
       matrix:
@@ -116,7 +116,7 @@ jobs:
   cpp-tests-extensive-windows:
     name: 🇨‌ Test (Extensive) 🏁
     needs: change-detection
-    if: fromJSON(needs.change-detection.outputs.run-cpp-tests) && github.event_name == 'pull_request' && contains(github.event.pull_request.labels.*.name, 'extensive-cpp-ci')
+    if: (fromJSON(needs.change-detection.outputs.run-cpp-tests) || fromJSON(needs.change-detection.outputs.run-mlir)) && github.event_name == 'pull_request' && contains(github.event.pull_request.labels.*.name, 'extensive-cpp-ci')
     strategy:
       fail-fast: false
       matrix:
@@ -132,7 +132,7 @@ jobs:
   cpp-coverage:
     name: 🇨‌ Coverage
     needs: change-detection
-    if: fromJSON(needs.change-detection.outputs.run-cpp-tests)
+    if: fromJSON(needs.change-detection.outputs.run-cpp-tests) || fromJSON(needs.change-detection.outputs.run-mlir)
     uses: munich-quantum-toolkit/workflows/.github/workflows/reusable-cpp-coverage.yml@7f8eeed7a3dba08e1e9be54966e5722f5753d0df # v1.17.7
     permissions:
       contents: read
@@ -262,15 +262,15 @@ jobs:
         with:
           allowed-skips: >-
             ${{
-              fromJSON(needs.change-detection.outputs.run-cpp-tests) && !contains(github.event.pull_request.labels.*.name, 'extensive-cpp-ci')
+              (fromJSON(needs.change-detection.outputs.run-cpp-tests) || fromJSON(needs.change-detection.outputs.run-mlir)) && !contains(github.event.pull_request.labels.*.name, 'extensive-cpp-ci')
               && '' || 'cpp-tests-ubuntu,cpp-tests-macos,cpp-tests-windows,'
             }}
             ${{
-              fromJSON(needs.change-detection.outputs.run-cpp-tests) && github.event_name == 'pull_request' && contains(github.event.pull_request.labels.*.name, 'extensive-cpp-ci')
+              (fromJSON(needs.change-detection.outputs.run-cpp-tests) || fromJSON(needs.change-detection.outputs.run-mlir)) && github.event_name == 'pull_request' && contains(github.event.pull_request.labels.*.name, 'extensive-cpp-ci')
               && '' || 'cpp-tests-extensive-ubuntu,cpp-tests-extensive-macos,cpp-tests-extensive-windows,'
             }}
             ${{
-              fromJSON(needs.change-detection.outputs.run-cpp-tests)
+              (fromJSON(needs.change-detection.outputs.run-cpp-tests) || fromJSON(needs.change-detection.outputs.run-mlir))
               && '' || 'cpp-coverage,'
             }}
             ${{

mlir/test/lit.cfg.py

@@ -38,7 +38,47 @@
 # Define where to execute tests (and produce the output).
 config.test_exec_root = Path(config.mqt_core_mlir_test_dir)
 
-multi_config_path = Path(config.mqt_core_mlir_tools_dir) / config.cmake_build_type
-tool_dirs = [config.llvm_tools_dir, config.mqt_core_mlir_tools_dir, str(multi_config_path)]
+# Build tool search paths
+# LLVM tools (FileCheck, not) come from LLVM installation
+# quantum-opt comes from our build directory
+base_tool_dir = Path(config.mqt_core_mlir_tools_dir)
+
+# For multi-config generators, $<CONFIG> is expanded at build time by CMake
+# For single-config generators, the path is the actual directory
+# We need to check if the path contains a valid binary location
+tool_dirs = [config.llvm_tools_dir]
+
+# Check if base_tool_dir exists and contains quantum-opt
+if base_tool_dir.exists():
+    if (base_tool_dir / "quantum-opt").exists() or (base_tool_dir / "quantum-opt.exe").exists():
+        tool_dirs.append(str(base_tool_dir))
+    else:
+        # For multi-config generators, check if parent directory exists
+        # This handles cases where $<CONFIG> didn't expand properly
+        parent_dir = base_tool_dir.parent
+        if parent_dir.exists():
+            # Search for quantum-opt in parent or common config directories
+            found = False
+            for candidate in [parent_dir] + [parent_dir / cfg for cfg in ["Release", "Debug", "RelWithDebInfo", "MinSizeRel"]]:
+                if (candidate / "quantum-opt").exists() or (candidate / "quantum-opt.exe").exists():
+                    tool_dirs.append(str(candidate))
+                    found = True
+                    break
+            if not found:
+                # Fallback: add parent directory anyway
+                tool_dirs.append(str(parent_dir))
+else:
+    # Path doesn't exist - likely $<CONFIG> not expanded
+    # Try parent directory
+    parent_dir = base_tool_dir.parent
+    if parent_dir.exists():
+        tool_dirs.append(str(parent_dir))
+        # Also try common config subdirectories
+        for cfg in ["Release", "Debug", "RelWithDebInfo", "MinSizeRel"]:
+            candidate = parent_dir / cfg
+            if (candidate / "quantum-opt").exists() or (candidate / "quantum-opt.exe").exists():
+                tool_dirs.append(str(candidate))
+                break
+
 tools = ["not", "FileCheck", "quantum-opt"]
 llvm_config.add_tool_substitutions(tools, tool_dirs)

mlir/test/lit.site.cfg.py.in

@@ -10,7 +10,8 @@
 
 config.llvm_tools_dir = lit_config.substitute("@LLVM_TOOLS_DIR@")
 config.cmake_build_type = "@CMAKE_BUILD_TYPE@"
-config.mqt_core_mlir_tools_dir = "@PROJECT_BINARY_DIR@/mlir/tools/quantum-opt"
+# Use generator expression to handle multi-config generators
+config.mqt_core_mlir_tools_dir = "@PROJECT_BINARY_DIR@/mlir/tools/quantum-opt/$<CONFIG>"
 config.mqt_core_mlir_test_dir = "@PROJECT_BINARY_DIR@/mlir/test"
 
 import lit.llvm