CMakeLists.txt

cmake_minimum_required(VERSION 3.16)
project(PagurusClangPlugin C CXX)

# ── Locate LLVM / Clang ───────────────────────────────────────────────────────
# Supports Clang/LLVM 11 through 18.
# Tested with: llvm-11-dev through llvm-18-dev
# Install on Debian/Ubuntu:
#   sudo apt install libclang-18-dev llvm-18-dev
find_package(LLVM REQUIRED CONFIG)
find_package(Clang REQUIRED CONFIG)

message(STATUS "Found LLVM ${LLVM_PACKAGE_VERSION}")
message(STATUS "  LLVM_INCLUDE_DIRS : ${LLVM_INCLUDE_DIRS}")
message(STATUS "  LLVM_LIBRARY_DIRS : ${LLVM_LIBRARY_DIRS}")
message(STATUS "  Clang includes    : ${CLANG_INCLUDE_DIRS}")

# Require C++17 (needed for structured bindings, std::optional, inline variables).
set(CMAKE_CXX_STANDARD 17)
set(CMAKE_CXX_STANDARD_REQUIRED ON)
set(CMAKE_EXPORT_COMPILE_COMMANDS ON)

# ── Optional: LLVM IR pass ────────────────────────────────────────────────────
# The IR pass (-fpass-plugin=) provides deeper alias/MemorySSA analysis but
# requires llvm/IR and llvm/Analysis headers (included in llvm-18-dev).
# Disable to build the AST-only plugin with reduced header requirements.
#
# To disable: cmake -DPAGURUS_WITH_IR_PASS=OFF ..
option(PAGURUS_WITH_IR_PASS "Build the LLVM IR borrow-check pass (-fpass-plugin=)" ON)
if(NOT PAGURUS_WITH_IR_PASS)
    message(STATUS "LLVM IR pass disabled (PAGURUS_WITH_IR_PASS=OFF) — AST-only build")
endif()

# ── Optional: MLIR ────────────────────────────────────────────────────────────
# Requires mlir-dev (not part of standard llvm-dev on most distros).
# When MLIR is found, enables the memref-dialect borrow analysis pass.
#
# Install (Ubuntu 22.04 with LLVM PPA):
#   sudo apt install libmlir-18-dev mlir-18-tools
#
# To enable: cmake -DPAGURUS_WITH_MLIR=ON -DMLIR_DIR=<mlir-cmake-dir> ..
option(PAGURUS_WITH_MLIR "Build with MLIR memref dialect analysis" OFF)
if(PAGURUS_WITH_MLIR)
    find_package(MLIR CONFIG REQUIRED)
    message(STATUS "Found MLIR ${MLIR_PACKAGE_VERSION}")
    message(STATUS "  MLIR_INCLUDE_DIRS: ${MLIR_INCLUDE_DIRS}")
    add_compile_definitions(PAGURUS_WITH_MLIR=1)
endif()

# ── LLVM analysis libraries required for the IR pass ─────────────────────────
# The -fpass-plugin= entry point (PagurusIRPass) requires:
#   LLVMPasses    : PassBuilder, PassPlugin, FunctionPassManager
#   LLVMAnalysis  : AliasAnalysis, BasicAA, MemorySSA, DominatorTree, CallGraph
#   LLVMCore      : IR types (Function, BasicBlock, Instruction, …)
#   LLVMSupport   : raw_ostream, StringRef, SmallVector, …
#   LLVMTransformUtils : createModuleToFunctionPassAdaptor
# These are resolved against the SHARED LLVM DSO (libLLVM-<ver>.so) to avoid
# symbol conflicts when the same LLVM is linked into both clang and the plugin.
if(PAGURUS_WITH_IR_PASS)
    llvm_map_components_to_libnames(LLVM_IR_LIBS
        Passes Analysis Core Support TransformUtils
    )
endif()

# ── Clang libraries required for the AST plugin ───────────────────────────────
# clangAST / clangFrontend / clangAnalysis are NOT linked directly because
# a Clang frontend plugin is loaded into an already-running clang process and
# must not double-link Clang symbols.  The symbols are resolved at dlopen-time
# from the host clang executable.  Listing them here as INTERFACE dependencies
# ensures the compiler finds the headers but does not emit link entries.
# (clangBasic is the only one that may need static linking for diagnostics.)

# ── The pagurus_plugin shared library ────────────────────────────────────────
add_library(pagurus_plugin MODULE src/pagurus_plugin.cpp)

target_include_directories(pagurus_plugin PRIVATE
    ${LLVM_INCLUDE_DIRS}
    ${CLANG_INCLUDE_DIRS}
)

if(PAGURUS_WITH_MLIR)
    target_include_directories(pagurus_plugin PRIVATE ${MLIR_INCLUDE_DIRS})
    # Link the MLIR umbrella shared library (libMLIR.so).  Unlike LLVM and
    # Clang, MLIR is NOT embedded in the clang binary, so the plugin must carry
    # the symbols itself.  Using the shared library avoids the symbol-bloat and
    # double-registration issues that come with linking many static MLIR .a
    # archives.  The `MLIR` cmake target is the SHARED IMPORTED target set up
    # by find_package(MLIR).
    target_link_libraries(pagurus_plugin PRIVATE MLIR)
endif()

separate_arguments(LLVM_DEFINITIONS_LIST UNIX_COMMAND "${LLVM_DEFINITIONS}")
target_compile_definitions(pagurus_plugin PRIVATE ${LLVM_DEFINITIONS_LIST})

if(NOT PAGURUS_WITH_IR_PASS)
    target_compile_definitions(pagurus_plugin PRIVATE PAGURUS_NO_IR_PASS=1)
endif()

# IMPORTANT: Do NOT link LLVM or Clang libraries statically into the plugin.
# A Clang frontend plugin (-fplugin=) is loaded into an already-running clang
# process that already has all LLVM/Clang symbols.  Linking them again causes
# double-registration of CommandLine options (fatal error at load time).
# Instead we use `--allow-shlib-undefined` so the linker accepts unresolved
# symbols that will be provided by the host clang at dlopen-time.
#
# For the IR pass (-fpass-plugin=), LLVM symbols are also resolved from the
# host clang/opt process, so no special linking is needed there either.
target_link_options(pagurus_plugin PRIVATE
    "-Wl,--allow-shlib-undefined"
    # Keep the plugin in memory after it's loaded (needed for static initializers).
    "-Wl,-z,nodelete"
)

# Plugin ABI flags: no SONAME prefix, hidden visibility for private symbols.
set_target_properties(pagurus_plugin PROPERTIES
    PREFIX ""
    SUFFIX ".so"
    CXX_VISIBILITY_PRESET hidden
    VISIBILITY_INLINES_HIDDEN ON
)

# Suppress -Wno-deprecated-declarations for FileEntry::getName() on Clang < 16.
target_compile_options(pagurus_plugin PRIVATE -Wno-deprecated-declarations)

# ── Install ───────────────────────────────────────────────────────────────────
install(TARGETS pagurus_plugin LIBRARY DESTINATION lib)

# ── CTest integration ─────────────────────────────────────────────────────────
# Enable CTest.  Each .c file in tests/ is registered as an individual
# test so that `ctest` (or `ctest -R pagurus_plugin`) gives per-test visibility.
#
# Build and test (replace 18 with 11–17 as needed):
#   cmake -DLLVM_DIR=$(llvm-config-18 --cmakedir) \
#         -DClang_DIR=/usr/lib/llvm-18/lib/cmake/clang ..
#   cmake --build .
#   ctest --output-on-failure
include(CTest)

if(BUILD_TESTING)
    # Locate the clang executable that matches the LLVM version we compiled with.
    find_program(CLANG_EXECUTABLE
        NAMES clang-${LLVM_VERSION_MAJOR} clang
        HINTS "${LLVM_TOOLS_BINARY_DIR}"
        DOC   "Clang executable used to run plugin tests"
    )

    if(CLANG_EXECUTABLE)
        set(PAGURUS_TEST_DIR    "${CMAKE_CURRENT_SOURCE_DIR}/tests")
        set(PAGURUS_TEST_RUNNER "${PAGURUS_TEST_DIR}/run_tests.sh")

        # Glob all .c test files so new ones are picked up automatically.
        # Exclude *.pagurus.c files — those are compile-mode output artefacts
        # produced by the plugin itself and are not test inputs.
        file(GLOB PAGURUS_TEST_SOURCES "${PAGURUS_TEST_DIR}/*.c")
        list(FILTER PAGURUS_TEST_SOURCES EXCLUDE REGEX "\\.pagurus\\.c$")

        foreach(test_src IN LISTS PAGURUS_TEST_SOURCES)
            get_filename_component(test_name "${test_src}" NAME_WE)
            add_test(
                NAME "pagurus_plugin_${test_name}"
                COMMAND bash "${PAGURUS_TEST_RUNNER}"
                             "$<TARGET_FILE:pagurus_plugin>"
                             "${test_src}"
            )
            set_tests_properties("pagurus_plugin_${test_name}" PROPERTIES
                ENVIRONMENT "CLANG=${CLANG_EXECUTABLE}"
            )
        endforeach()

        # ── Multi-file / whole-project integration tests ──────────────────────
        # Tests that verify pagurus-check and pagurus.mk work correctly across
        # a small multi-translation-unit project (tests/multifile/).
        set(PAGURUS_MULTIFILE_RUNNER "${PAGURUS_TEST_DIR}/run_multifile_tests.sh")
        set(PAGURUS_MULTIFILE_DIR    "${PAGURUS_TEST_DIR}/multifile")

        add_test(
            NAME "pagurus_multifile"
            COMMAND bash "${PAGURUS_MULTIFILE_RUNNER}"
                         "$<TARGET_FILE:pagurus_plugin>"
                         "${PAGURUS_MULTIFILE_DIR}"
        )
        set_tests_properties("pagurus_multifile" PROPERTIES
            ENVIRONMENT "CLANG=${CLANG_EXECUTABLE}"
        )

        message(STATUS
            "Plugin tests registered: ${CMAKE_CURRENT_BINARY_DIR} "
            "(run with: ctest --output-on-failure)")
    else()
        message(STATUS
            "Clang executable not found — plugin tests will not be registered. "
            "Set CLANG_EXECUTABLE or ensure clang is on PATH.")
    endif()
endif()