Depend on Boost using FetchContent instead of relying on system-provi…

…ded Boost.

CMakeLists.txt

@@ -152,10 +152,6 @@ if(STATIC_BUILD_WITH_DYNAMIC_GLIBC OR STATIC_BUILD_WITH_DYNAMIC_STDLIB)
   endif()
   set(BUILD_SHARED_LIBS OFF)
   set(CMAKE_FIND_LIBRARY_SUFFIXES .a)
-  # Link Boost statically
-  # See https://cmake.org/cmake/help/latest/module/FindBoost.html for details
-  set(Boost_USE_STATIC_LIBS ON)
-  set(Boost_USE_STATIC_RUNTIME OFF)
   # Set the static variable
   set(P4C_STATIC_BUILD STATIC)
   # TODO: We can not use -static here because of compilation and portability problems:
@@ -203,20 +199,13 @@ include(Abseil)
 p4c_obtain_abseil()
 include(Protobuf)
 p4c_obtain_protobuf()
+include(Boost)
+p4c_obtain_boost()
 
 # We require -pthread to make std::call_once work, even if we're not using threads...
 set(THREADS_PREFER_PTHREAD_FLAG ON)
 find_package(Threads REQUIRED)
 
-# The boost graph headers are optional and only required by the graphs back end.
-find_package (Boost QUIET COMPONENTS graph)
-if (Boost_FOUND)
-  set (HAVE_LIBBOOST_GRAPH 1)
-else ()
-  message (WARNING "Boost graph headers not found, will not build 'graphs' backend")
-endif ()
-find_package (Boost REQUIRED COMPONENTS iostreams)
-
 # Compile with the Boehm garbage collector (https://github.com/ivmai/bdwgc), if requested.
 # One can disable the GC, e.g., to run under Valgrind, by editing config.h.
 if (ENABLE_GC)
@@ -227,10 +216,7 @@ if (ENABLE_MULTITHREAD)
   add_definitions(-DMULTITHREAD)
 endif()
 list (APPEND P4C_LIB_DEPS ${CMAKE_THREAD_LIBS_INIT})
-include_directories(SYSTEM ${Boost_INCLUDE_DIRS})
-include_directories(SYSTEM ${PROTOBUF_INCLUDE_DIRS})
-set (HAVE_LIBBOOST_IOSTREAMS 1)
-list (APPEND P4C_LIB_DEPS ${Boost_LIBRARIES})
+include_directories(BEFORE SYSTEM ${PROTOBUF_INCLUDE_DIRS})
 if (ENABLE_GC)
   list (APPEND P4C_LIB_DEPS ${LIBGC_LIBRARIES})
 endif ()

cmake/Boost.cmake

@@ -0,0 +1,95 @@
+macro(p4c_obtain_boost)
+  option(
+    P4C_USE_PREINSTALLED_BOOST
+    "Look for a preinstalled version of Boost in the system instead of installing the library using FetchContent."
+    OFF
+  )
+
+  set(P4C_BOOST_VERSION "1.85.0")
+
+  # If P4C_USE_PREINSTALLED_BOOST is ON just try to find a preinstalled version of Boost.
+  if(P4C_USE_PREINSTALLED_BOOST)
+    if(NOT BUILD_SHARED_LIBS)
+      # Link Boost statically
+      # See https://cmake.org/cmake/help/latest/module/FindBoost.html for details
+      set(Boost_USE_STATIC_LIBS ON)
+      set(Boost_USE_STATIC_RUNTIME OFF)
+    endif()
+
+    # The boost graph headers are optional and only required by the graphs back end.
+    find_package (Boost QUIET COMPONENTS graph)
+    if (Boost_FOUND)
+      set (HAVE_LIBBOOST_GRAPH 1)
+    else ()
+      message (WARNING "Boost graph headers not found, will not build 'graphs' backend")
+    endif ()
+    find_package (Boost REQUIRED COMPONENTS format multiprecision)
+    include_directories(BEFORE SYSTEM ${Boost_INCLUDE_DIRS})
+
+  else()
+    message(STATUS "Fetching Boost version ${P4C_BOOST_VERSION} for P4C...")
+    # Print out download state while setting up Boost.
+    set(FETCHCONTENT_QUIET_PREV ${FETCHCONTENT_QUIET})
+    set(FETCHCONTENT_QUIET OFF)
+    # Unity builds do not work for Abseil...
+    set(CMAKE_UNITY_BUILD_PREV ${CMAKE_UNITY_BUILD})
+    set(CMAKE_UNITY_BUILD OFF)
+
+
+    # Add boost library sources.
+    set(BOOST_INCLUDE_LIBRARIES graph format multiprecision iostreams)
+    set(BOOST_ENABLE_CMAKE ON)
+
+    if (ENABLE_P4C_GRAPHS)
+      set(HAVE_LIBBOOST_GRAPH 1)
+    endif()
+
+    # Always link Boost statically.
+    set(Boost_USE_STATIC_LIBS ON)
+    set(Boost_USE_STATIC_RUNTIME OFF)
+    # set(BOOST_MP_STANDALONE ON CACHE BOOL "Use Boost.Multiprecision in standalone mode")
+
+    # Download and extract the boost library from GitHub.
+    message(STATUS "Downloading and extracting boost library sources. This may take some time...")
+    FetchContent_Declare(
+        Boost
+        URL https://github.com/boostorg/boost/releases/download/boost-${P4C_BOOST_VERSION}/boost-${P4C_BOOST_VERSION}-cmake.tar.xz
+        USES_TERMINAL_DOWNLOAD TRUE
+        GIT_PROGRESS TRUE
+    )
+    FetchContent_MakeAvailable(Boost)
+
+    # Force inclusion of the correct Boost headers. This is necessary because users may have their own system boost headers which can be in conflict.
+    set (Boost_INCLUDE_DIRS ${Boost_BINARY_DIR}/include)
+    file(GLOB __boost_include_directories
+        ${Boost_SOURCE_DIR}/libs/**/include ${Boost_SOURCE_DIR}/libs/**/**/include
+    )
+    foreach(__boost_include_directory ${__boost_include_directories})
+      if(IS_DIRECTORY ${__boost_include_directory})
+        include_directories(BEFORE SYSTEM ${__boost_include_directory})
+      endif()
+    endforeach()
+    # Suppress warnings for all Boost targets.
+    get_all_targets(BOOST_BUILD_TARGETS ${Boost_SOURCE_DIR})
+    foreach(target in ${BOOST_BUILD_TARGETS})
+      if(target MATCHES "boost_*")
+        # Do not suppress warnings for Boost library targets that are aliased.
+        get_target_property(target_type ${target} TYPE)
+        if (NOT ${target_type} STREQUAL "INTERFACE_LIBRARY")
+          target_compile_options(${target} PRIVATE "-Wno-error" "-w")
+        endif()
+      endif()
+    endforeach()
+
+
+    # Reset temporary variable modifications.
+    set(CMAKE_UNITY_BUILD ${CMAKE_UNITY_BUILD_PREV})
+    set(FETCHCONTENT_QUIET ${FETCHCONTENT_QUIET_PREV})
+  endif()
+
+  set(HAVE_LIBBOOST_IOSTREAMS TRUE)
+  set (P4C_BOOST_LIBRARIES Boost::iostreams Boost::format Boost::multiprecision)
+  list(APPEND P4C_LIB_DEPS ${P4C_BOOST_LIBRARIES})
+
+  message(STATUS "Done with setting up Boost for P4C.")
+endmacro(p4c_obtain_boost)

tools/ci-build.sh

@@ -71,9 +71,6 @@ P4C_DEPS="bison \
           g++ \
           git \
           lld \
-          libboost-dev \
-          libboost-graph-dev \
-          libboost-iostreams-dev \
           libfl-dev \
           pkg-config \
           python3 \

tools/install_mac_deps.sh

@@ -37,21 +37,14 @@ HOMEBREW_PREFIX=$(brew --prefix)
 # Fetch the latest formulae
 brew update
 
-BOOST_LIB="[email protected]"
 REQUIRED_PACKAGES=(
     autoconf automake ccache cmake libtool
     openssl pkg-config coreutils bison grep ninja
-    ${BOOST_LIB}
 )
 for package in "${REQUIRED_PACKAGES[@]}"; do
   brew_install ${package}
 done
 
-# Check if linking is needed.
-if ! brew ls --linked --formula ${BOOST_LIB} > /dev/null 2>&1; then
-  brew link ${BOOST_LIB}
-fi
-
 # Check if PATH modification is needed.
 if ! grep -q "$(brew --prefix bison)/bin" ~/.bash_profile; then
   echo 'export PATH="$(brew --prefix bison)/bin:$PATH"' >> ~/.bash_profile