can use bundled Boost.CallableTraits only if don't have real Boost an…

…d TTG_FETCH_BOOST is not set

CMakeLists.txt

@@ -58,7 +58,7 @@ option(TTG_EXAMPLES "Whether to build examples" OFF)
 option(TTG_ENABLE_ASAN "Whether to enable address sanitizer" OFF)
 
 option(TTG_FETCH_BOOST "Whether to fetch+build Boost, if missing" OFF)
-option(TTG_IGNORE_BUNDLED_EXTERNALS "Whether to skip installation and use of bundled external depenedencies (Boost.CallableTraits)" OFF)
+option(TTG_IGNORE_BUNDLED_EXTERNALS "Whether to skip installation and use of bundled external dependencies (Boost.CallableTraits)" OFF)
 option(TTG_ENABLE_TRACE "Whether to enable ttg::trace() output" OFF)
 # See https://medium.com/@alasher/colored-c-compiler-output-with-ninja-clang-gcc-10bfe7f2b949
 option (FORCE_COLORED_OUTPUT "Always produce ANSI-colored output (GNU/Clang only)." TRUE)

cmake/modules/ExternalDependenciesVersions.cmake

@@ -3,7 +3,7 @@
 
 # need Boost.CallableTraits (header only, part of Boost 1.66 released in Dec 2017) for wrap.h to work
 set(TTG_TRACKED_BOOST_VERSION 1.66)
-set(TTG_TRACKED_VG_CMAKE_KIT_TAG d5c0a6f9ff6dc97cbb5132912733e1eb1cf73f1e)  # used to provide "real" FindOrFetchBoost
+set(TTG_TRACKED_VG_CMAKE_KIT_TAG 7ea2d4d3f8854b9e417f297fd74d6fc49aa13fd5)  # used to provide "real" FindOrFetchBoost
 set(TTG_TRACKED_CATCH2_VERSION 3.5.0)
 set(TTG_TRACKED_CEREAL_VERSION 1.3.0)
 set(TTG_TRACKED_MADNESS_TAG 8788aea9758bfe6479cc23d39e6c77b7528009db)

cmake/modules/FindOrFetchBoost.cmake

@@ -1,24 +1,38 @@
 # Boost can be discovered by every (sub)package but only the top package can *build* it ...
-# in either case must declare the components used by TA
+# in either case must declare the components used by TTG
 set(required_components
         headers
         callable_traits
 )
+set(optional_components
+)
 if (TTG_PARSEC_USE_BOOST_SERIALIZATION)
-    list(APPEND required_components
+    list(APPEND optional_components
             serialization
             iostreams
     )
 endif()
+
+# if not allowed to fetch Boost make all Boost optional
+if (NOT DEFINED Boost_FETCH_IF_MISSING AND TTG_FETCH_BOOST)
+    set(Boost_FETCH_IF_MISSING 1)
+endif()
+if (NOT Boost_FETCH_IF_MISSING)
+    foreach(__component IN LISTS required_components)
+    list(APPEND optional_components
+            ${__component}
+    )
+    endforeach()
+    set(required_components )
+endif()
+
 if (DEFINED Boost_REQUIRED_COMPONENTS)
     list(APPEND Boost_REQUIRED_COMPONENTS
             ${required_components})
     list(REMOVE_DUPLICATES Boost_REQUIRED_COMPONENTS)
 else()
     set(Boost_REQUIRED_COMPONENTS "${required_components}" CACHE STRING "Components of Boost to discovered or built")
 endif()
-set(optional_components
-)
 if (DEFINED Boost_OPTIONAL_COMPONENTS)
     list(APPEND Boost_OPTIONAL_COMPONENTS
             ${optional_components}
@@ -28,10 +42,6 @@ else()
     set(Boost_OPTIONAL_COMPONENTS "${optional_components}" CACHE STRING "Optional components of Boost to discovered or built")
 endif()
 
-if (NOT DEFINED Boost_FETCH_IF_MISSING AND TTG_FETCH_BOOST)
-    set(Boost_FETCH_IF_MISSING 1)
-endif()
-
 # Bring ValeevGroup cmake toolkit, if not yet available
 if (NOT DEFINED vg_cmake_kit_SOURCE_DIR)
     include(FetchContent)
@@ -53,3 +63,6 @@ if (NOT DEFINED vg_cmake_kit_SOURCE_DIR)
 endif()
 include(${vg_cmake_kit_SOURCE_DIR}/modules/FindOrFetchBoost.cmake)
 
+if (TARGET Boost::headers)
+    set(TTG_HAS_BOOST 1)
+endif()

cmake/ttg-config.cmake.in

@@ -6,11 +6,10 @@ set(TTG_EXT_VERSION "@TTG_EXT_VERSION@")
 
 set(PaRSEC_CONFIG "@PaRSEC_CONFIG@")
 set(MADNESS_CONFIG "@MADNESS_CONFIG@")
-set(Boost_CONFIG "@Boost_CONFIG@")
 set(CXX_COROUTINE_COMPONENT "@CXX_COROUTINE_COMPONENT@")
 
 set(TTG_TRACKED_BOOST_VERSION "@TTG_TRACKED_BOOST_VERSION@")
-
+set(TTG_HAS_BOOST @TTG_HAS_BOOST@)
 set(TTG_IGNORE_BUNDLED_EXTERNALS @TTG_IGNORE_BUNDLED_EXTERNALS@)
 
 # make TTG CMake modules discoverable + load AddTTGExecutable by default
@@ -19,6 +18,10 @@ include(AddTTGExecutable)
 
 @PACKAGE_INIT@
 
+if (TTG_HAS_BOOST)
+@Boost_CONFIG_FILE_CONTENTS@
+endif(TTG_HAS_BOOST)
+
 if (NOT TARGET MADworld AND MADNESS_CONFIG)
   get_filename_component(MADNESS_CONFIG_DIR "${MADNESS_CONFIG}" DIRECTORY)
   find_package(MADNESS 0.10.1 CONFIG QUIET REQUIRED COMPONENTS world PATHS "${MADNESS_CONFIG_DIR}" NO_DEFAULT_PATH)
@@ -29,12 +32,6 @@ if (NOT TARGET PaRSEC::parsec AND PaRSEC_CONFIG)
   find_package(PaRSEC CONFIG QUIET REQUIRED COMPONENTS parsec PATHS "${PaRSEC_CONFIG_DIR}" NO_DEFAULT_PATH)
 endif()
 
-# if Boost was discovered and used at TTG configure time discover Boost at the same path
-if (NOT TARGET Boost::boost AND Boost_CONFIG)
-  get_filename_component(Boost_CONFIG_DIR "${Boost_CONFIG}" DIRECTORY)
-  find_package(Boost ${TTG_TRACKED_BOOST_VERSION} CONFIG QUIET REQUIRED OPTIONAL_COMPONENTS serialization PATHS "${Boost_CONFIG_DIR}" NO_DEFAULT_PATH)
-endif()
-
 # if C++ coroutines were used discover same version of them
 if (NOT TARGET std::coroutine AND CXX_COROUTINE_COMPONENT)
   find_package(CXXStdCoroutine MODULE QUIET REQUIRED COMPONENTS "${CXX_COROUTINE_COMPONENT}")
@@ -48,13 +45,4 @@ if(NOT TARGET ttg)
   endif()
 endif()
 
-# if don't have Boost, use bundled Boost.CallableTraits
-if (NOT TARGET Boost::boost)
-  if (TTG_IGNORE_BUNDLED_EXTERNALS)
-    find_package(Boost ${TTG_TRACKED_BOOST_VERSION} QUIET REQUIRED)
-  else()
-    target_compile_definitions(ttg INTERFACE TTG_USE_BUNDLED_BOOST_CALLABLE_TRAITS=1)
-  endif()
-endif()
-
 set(TTG_FOUND TRUE)