Make all public API functions dispatchable from a single .td definition. (#906)

Default arguments were lost through the dispatch function pointer
indirection, requiring ~245 DFLT_* macro workarounds across the test
suite. 47 public functions were not dispatchable at all. Function
signatures in the dispatch table could drift from CppInterOp.h
because the two were maintained independently.

Author: vgvassilev

.github/actions/Build_and_Test_CppInterOp/action.yml

@@ -177,6 +177,22 @@ runs:
           CPLUS_INCLUDE_PATH="${LLVM_DIR}/llvm/include:${LLVM_DIR}/clang/include:${LLVM_BUILD_DIR}/include:${LLVM_BUILD_DIR}/tools/clang/include:$PWD/include"
         fi
 
+        # Build native cppinterop-tblgen for .inc file generation.
+        # Use the native LLVM build (not the Emscripten cross-build) since
+        # cppinterop-tblgen only needs libLLVMTableGen and libLLVMSupport.
+        NATIVE_LLVM_BUILD_DIR="$(pwd)/llvm-project/native_build"
+        mkdir -p native_cppinterop_build && pushd native_cppinterop_build
+        cmake -DCMAKE_BUILD_TYPE=Release \
+              -DLLVM_DIR=$NATIVE_LLVM_BUILD_DIR/lib/cmake/llvm \
+              -DCPPINTEROP_ENABLE_TESTING=OFF \
+              -DCPPINTEROP_BUILD_TABLEGEN_ONLY=ON \
+              ../
+        cmake --build . --target cppinterop-tblgen -j ${{ env.ncpus }}
+        export CPPINTEROP_TBLGEN_EXE=$(find $PWD -name cppinterop-tblgen -type f | head -1)
+        echo "Found cppinterop-tblgen at: $CPPINTEROP_TBLGEN_EXE"
+        echo "CPPINTEROP_TBLGEN_EXE=$CPPINTEROP_TBLGEN_EXE" >> $GITHUB_ENV
+        popd
+
         # Build CppInterOp next to cling and llvm-project.
         mkdir build
         cd build
@@ -195,6 +211,7 @@ runs:
                 -DCMAKE_FIND_ROOT_PATH_MODE_PACKAGE=ON            \
                 -DLLVM_ENABLE_WERROR=On                      \
                 -DSYSROOT_PATH=$SYSROOT_PATH               \
+                -DCPPINTEROP_TABLEGEN_EXE=$CPPINTEROP_TBLGEN_EXE \
                 ../
         else
           emcmake cmake -DCMAKE_BUILD_TYPE=${{ env.BUILD_TYPE }}    \
@@ -208,6 +225,7 @@ runs:
                 -DCMAKE_FIND_ROOT_PATH_MODE_PACKAGE=ON            \
                 -DLLVM_ENABLE_WERROR=On                      \
                 -DSYSROOT_PATH=$SYSROOT_PATH                     \
+                -DCPPINTEROP_TABLEGEN_EXE=$CPPINTEROP_TBLGEN_EXE \
                 ../
         fi
         emmake make -j ${{ env.ncpus }} check-cppinterop
@@ -353,6 +371,7 @@ runs:
                 -DCMAKE_FIND_ROOT_PATH_MODE_PACKAGE=ON            \
                 -DLLVM_ENABLE_WERROR=On                      \
                 -DSYSROOT_PATH=${{ env.SYSROOT_PATH }}              \
+                -DCPPINTEROP_TABLEGEN_EXE=$CPPINTEROP_TBLGEN_EXE \
                 ../
         else
           emcmake cmake -DCMAKE_BUILD_TYPE=${{ env.BUILD_TYPE }}    \
@@ -365,6 +384,7 @@ runs:
                 -DCMAKE_FIND_ROOT_PATH_MODE_PACKAGE=ON            \
                 -DLLVM_ENABLE_WERROR=On                      \
                 -DSYSROOT_PATH=${{ env.SYSROOT_PATH }}                  \
+                -DCPPINTEROP_TABLEGEN_EXE=$CPPINTEROP_TBLGEN_EXE \
                 ../
         fi
         os="${{ matrix.os }}"
@@ -461,6 +481,21 @@ runs:
           echo "CPLUS_INCLUDE_PATH=$env:CPLUS_INCLUDE_PATH" >> $env:GITHUB_ENV
         }
 
+        # Build native cppinterop-tblgen for .inc file generation.
+        mkdir native_cppinterop_build
+        pushd native_cppinterop_build
+        $env:NATIVE_LLVM_BUILD_DIR="$env:PWD_DIR\llvm-project\native_build"
+        cmake -DCMAKE_BUILD_TYPE=Release `
+              -DLLVM_DIR="$env:NATIVE_LLVM_BUILD_DIR\lib\cmake\llvm" `
+              -DCPPINTEROP_ENABLE_TESTING=OFF `
+              -DCPPINTEROP_BUILD_TABLEGEN_ONLY=ON `
+              ..\
+        cmake --build . --target cppinterop-tblgen -j ${{ env.ncpus }}
+        $env:CPPINTEROP_TBLGEN_EXE = (Get-ChildItem -Recurse -Filter "cppinterop-tblgen.exe" | Select-Object -First 1).FullName
+        echo "Found cppinterop-tblgen at: $env:CPPINTEROP_TBLGEN_EXE"
+        echo "CPPINTEROP_TBLGEN_EXE=$env:CPPINTEROP_TBLGEN_EXE" >> $env:GITHUB_ENV
+        popd
+
         # Build CppInterOp next to cling and llvm-project.
         mkdir build
         cd build
@@ -480,6 +515,7 @@ runs:
                 -DCMAKE_FIND_ROOT_PATH_MODE_PACKAGE=ON            `
                 -DLLVM_ENABLE_WERROR=On                      `
                 -DSYSROOT_PATH="$env:SYSROOT_PATH"              `
+                -DCPPINTEROP_TABLEGEN_EXE="$env:CPPINTEROP_TBLGEN_EXE" `
                 ..\
         }
         else
@@ -495,6 +531,7 @@ runs:
                 -DCMAKE_FIND_ROOT_PATH_MODE_PACKAGE=ON            `
                 -DLLVM_ENABLE_WERROR=On                      `
                 -DSYSROOT_PATH="$env:SYSROOT_PATH"                     `
+                -DCPPINTEROP_TABLEGEN_EXE="$env:CPPINTEROP_TBLGEN_EXE" `
                 ..\
         }
         function Error-OnFailure {
@@ -570,6 +607,7 @@ runs:
                 -DCMAKE_FIND_ROOT_PATH_MODE_PACKAGE=ON            `
                 -DLLVM_ENABLE_WERROR=On                      `
                 -DSYSROOT_PATH=${{ env.SYSROOT_PATH }}             `
+                -DCPPINTEROP_TABLEGEN_EXE="${{ env.CPPINTEROP_TBLGEN_EXE }}" `
                 ..\
         }
         else
@@ -584,6 +622,7 @@ runs:
                 -DCMAKE_FIND_ROOT_PATH_MODE_PACKAGE=ON            `
                 -DLLVM_ENABLE_WERROR=On                      `
                 -DSYSROOT_PATH=${{ env.SYSROOT_PATH }}                    `
+                -DCPPINTEROP_TABLEGEN_EXE="${{ env.CPPINTEROP_TBLGEN_EXE }}" `
                 ..\
         }
         Error-OnFailure { emmake make -j ${{ env.ncpus }} check-cppinterop }

.github/workflows/clang-tidy-review.yml

@@ -35,17 +35,34 @@ jobs:
         id: review
         with:
           build_dir: build
-          apt_packages: cmake,libxml2,libxml2-dev,libtinfo-dev,zlib1g-dev,libzstd-dev
+          # llvm-dev provides linkable libLLVMTableGen.a for building
+          # cppinterop-tblgen. The KyleMayes binary LLVM distribution has
+          # incompatible .a files. The system LLVM version doesn't need to
+          # match CppInterOp's minimum (19) since the TableGen library API
+          # is stable — only the tblgen binary is built against it. The
+          # real CppInterOp analysis uses the KyleMayes LLVM via LLVM_DIR.
+          apt_packages: cmake,libxml2,libxml2-dev,libtinfo-dev,zlib1g-dev,libzstd-dev,llvm-dev
           split_workflow: true
           config_file: .clang-tidy
+          # Two-stage cmake: (1) build cppinterop-tblgen against system
+          # LLVM, (2) configure CppInterOp against KyleMayes LLVM with the
+          # native tblgen binary, then generate .inc files.
           cmake_command: >
+            SYSTEM_LLVM_DIR=$(find /usr/lib/llvm-* -path '*/cmake/llvm/LLVMConfig.cmake' -printf '%h' -quit 2>/dev/null || echo "/usr/lib/llvm-18/lib/cmake/llvm") &&
+            cmake . -B tblgen_build -DCMAKE_BUILD_TYPE=Release
+            -DLLVM_DIR=$SYSTEM_LLVM_DIR
+            -DCPPINTEROP_BUILD_TABLEGEN_ONLY=ON &&
+            cmake --build tblgen_build --target cppinterop-tblgen --parallel $(nproc --all) &&
+            TBLGEN_EXE=$(find $(pwd)/tblgen_build -name cppinterop-tblgen -type f | head -1) &&
             cmake . -B build -DCMAKE_BUILD_TYPE="Release"
             -DCMAKE_C_COMPILER="$GITHUB_WORKSPACE/llvm/bin/clang"
             -DCMAKE_CXX_COMPILER="$GITHUB_WORKSPACE/llvm/bin/clang++"
             -DLLVM_DIR="$GITHUB_WORKSPACE/llvm"
             -DBUILD_SHARED_LIBS=ON
-            -DCMAKE_EXPORT_COMPILE_COMMANDS=ON &&
+            -DCMAKE_EXPORT_COMPILE_COMMANDS=ON
+            -DCPPINTEROP_TABLEGEN_EXE=$TBLGEN_EXE &&
             cd build &&
+            cmake --build . --target CppInterOpTableGen --parallel $(nproc --all) &&
             cmake --build . --target googletest --parallel $(nproc --all)
 
       - name: Upload artifacts

CMakeLists.txt

@@ -12,6 +12,7 @@ set(CMAKE_CXX_EXTENSIONS NO)
 option(CPPINTEROP_USE_CLING "Use Cling as backend" OFF)
 option(CPPINTEROP_USE_REPL "Use clang-repl as backend" ON)
 option(CPPINTEROP_ENABLE_TESTING "Enable the CppInterOp testing infrastructure." ON)
+option(CPPINTEROP_BUILD_TABLEGEN_ONLY "Only build cppinterop-tblgen (for cross-compilation)" OFF)
 if(EMSCRIPTEN)
   set(CPPINTEROP_EXTRA_WASM_FLAGS "-fwasm-exceptions" CACHE STRING "Extra flags for wasm")
 endif()
@@ -24,6 +25,19 @@ endif()
 if( CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR )
   project(CppInterOp)
 
+  # When only building cppinterop-tblgen for cross-compilation, skip
+  # all find_package calls and library/test subdirectories. Only needs
+  # LLVM_DIR pointing to a native LLVM build with libLLVMTableGen.
+  if(CPPINTEROP_BUILD_TABLEGEN_ONLY)
+    find_package(LLVM REQUIRED CONFIG)
+    include_directories(${LLVM_INCLUDE_DIRS})
+    include(AddLLVM)
+    include(HandleLLVMOptions)
+    include(TableGen)
+    add_subdirectory(utils/TableGen)
+    return()
+  endif()
+
   if (NOT CMAKE_BUILD_TYPE AND NOT CMAKE_CONFIGURATION_TYPES)
     message(WARNING "No build type selected. Defaulted CMAKE_BUILD_TYPE=Release.\n"
       "Valid options are: None, Debug, Release, RelWithDebInfo, MinSizeRel.")
@@ -300,10 +314,14 @@ endif()
 
   include(AddLLVM)
   include(HandleLLVMOptions)
+  include(TableGen)
 endif()
 
 set(CMAKE_INCLUDE_CURRENT_DIR ON)
 
+# Generated .inc files from cppinterop-tblgen live under the build tree.
+include_directories(${CMAKE_BINARY_DIR}/include)
+
 # In rare cases we might want to have clang installed in a different place
 # than llvm and the header files should be found first (even though the
 # LLVM_INCLUDE_DIRS) contain clang headers, too.
@@ -443,6 +461,7 @@ install(DIRECTORY include/
   FILES_MATCHING
   PATTERN "*.def"
   PATTERN "*.h"
+  PATTERN "*.inc"
   PATTERN ".svn" EXCLUDE
   )
 
@@ -548,6 +567,9 @@ if (CPPINTEROP_INCLUDE_DOCS)
   add_subdirectory(docs)
 endif()
 
+if(NOT EMSCRIPTEN AND NOT CPPINTEROP_TABLEGEN_EXE)
+  add_subdirectory(utils/TableGen)
+endif()
 add_subdirectory(lib)
 if (CPPINTEROP_ENABLE_TESTING)
   add_subdirectory(unittests)

docs/Emscripten-build-instructions.rst

@@ -208,7 +208,44 @@ and
    $env:CMAKE_PREFIX_PATH=$env:PREFIX
    $env:CMAKE_SYSTEM_PREFIX_PATH=$env:PREFIX
 
-on Windows. Now to build and test your Emscripten build of CppInterOp on Linux and osx execute the following
+on Windows. Before building the Emscripten version of CppInterOp, we need
+to build ``cppinterop-tblgen`` natively. This tool generates ``.inc`` files
+from ``.td`` definitions and must run on the host (not under Emscripten).
+We use the native LLVM build from the earlier step since it has the required
+``libLLVMTableGen`` library.
+
+On Linux and osx:
+
+.. code:: bash
+
+   cd ../CppInterOp/
+   NATIVE_LLVM_BUILD_DIR=$(pwd)/../llvm-project/native_build
+   mkdir -p native_cppinterop_build && cd native_cppinterop_build
+   cmake -DCMAKE_BUILD_TYPE=Release \
+         -DLLVM_DIR=$NATIVE_LLVM_BUILD_DIR/lib/cmake/llvm \
+         -DCPPINTEROP_BUILD_TABLEGEN_ONLY=ON \
+         ../
+   cmake --build . --target cppinterop-tblgen -j $(nproc --all)
+   export CPPINTEROP_TBLGEN_EXE=$(find $PWD -name cppinterop-tblgen -type f | head -1)
+   cd ..
+
+On Windows:
+
+.. code:: powershell
+
+   cd ..\CppInterOp\
+   $env:NATIVE_LLVM_BUILD_DIR="$env:PWD_DIR\llvm-project\native_build"
+   mkdir native_cppinterop_build
+   cd native_cppinterop_build
+   cmake -DCMAKE_BUILD_TYPE=Release `
+         -DLLVM_DIR="$env:NATIVE_LLVM_BUILD_DIR\lib\cmake\llvm" `
+         -DCPPINTEROP_BUILD_TABLEGEN_ONLY=ON `
+         ..\
+   cmake --build . --target cppinterop-tblgen -j $(nproc --all)
+   $env:CPPINTEROP_TBLGEN_EXE = (Get-ChildItem -Recurse -Filter "cppinterop-tblgen.exe" | Select-Object -First 1).FullName
+   cd ..
+
+Now to build and test your Emscripten build of CppInterOp on Linux and osx execute the following
 (BUILD_SHARED_LIBS=ON is only needed if building xeus-cpp, as CppInterOp can be built as an Emscripten static library)
 
 .. code:: bash
@@ -223,6 +260,7 @@ on Windows. Now to build and test your Emscripten build of CppInterOp on Linux a
                  -DCMAKE_FIND_ROOT_PATH_MODE_PACKAGE=ON            \
                  -DCMAKE_INSTALL_PREFIX=$PREFIX         \
                  -DSYSROOT_PATH=$SYSROOT_PATH                                   \
+                 -DCPPINTEROP_TABLEGEN_EXE=$CPPINTEROP_TBLGEN_EXE \
                  ../
    emmake make -j $(nproc --all) check-cppinterop
 
@@ -241,6 +279,7 @@ To build and test your Emscripten build of CppInterOp on Windows execute the fol
                 -DCMAKE_FIND_ROOT_PATH_MODE_PACKAGE=ON            `
                 -DLLVM_ENABLE_WERROR=On                      `
                 -DSYSROOT_PATH="$env:SYSROOT_PATH"                     `
+                -DCPPINTEROP_TABLEGEN_EXE="$env:CPPINTEROP_TBLGEN_EXE" `
                 ..\
    emmake make -j $(nproc --all) check-cppinterop