Be explicit about not using C++ modules

Only files that CMake knows won't interact with C++ modules are eligible
for becoming part of unity builds. Hence, being explicit about this can
speed up builds.

Additionally, this avoids the need for the actual module scanning steps
as well as generation of module binary files.

Author: Krzmbrzl

CMakeLists.txt

@@ -86,6 +86,7 @@ include(compiler)
 macro(sequant_add_library _module)
     add_library(SeQuant-${_module} ${ARGN})
     set_target_properties(SeQuant-${_module} PROPERTIES EXPORT_NAME ${_module})
+    set_target_properties(SeQuant-${_module} PROPERTIES CXX_SCAN_FOR_MODULES OFF)
     add_library(SeQuant::${_module} ALIAS SeQuant-${_module})
     get_target_property(_type SeQuant-${_module} TYPE)
     if (NOT _type STREQUAL "INTERFACE_LIBRARY")

benchmarks/CMakeLists.txt

@@ -11,6 +11,8 @@ add_executable(sequant_benchmarks
         "wick.cpp"
 )
 
+set_target_properties(sequant_benchmarks PROPERTIES CXX_SCAN_FOR_MODULES OFF)
+
 # The benchmark implementations contain a bunch of same-name symbol definition that
 # ought to be local to the individual translation unit. Hence, we must not combine
 # all of them into a single translation unit.

doc/examples/CMakeLists.txt

@@ -34,6 +34,7 @@ foreach(current IN LISTS EXAMPLE_CODES)
     endif()
 
     target_link_libraries(${current_name} PRIVATE SeQuant)
+    set_target_properties(${current_name} PROPERTIES CXX_SCAN_FOR_MODULES OFF)
 
     # Make sure the user sees as little from these as possible
     set_target_properties(${current_name}

tests/integration/CMakeLists.txt

@@ -42,6 +42,7 @@ foreach(current IN LISTS TEST_CASES)
     string(REGEX REPLACE "\\.cpp$" "" test_name "${test_source}")
 
     add_executable(${test_name} ${BUILD_BY_DEFAULT} ${test_source})
+    set_target_properties(${test_name} PROPERTIES CXX_SCAN_FOR_MODULES OFF)
     target_link_libraries(${test_name} PRIVATE SeQuant)
 
     if (SEQUANT_INTERNAL_SKIP_LONG_TESTS)

tests/integration/eval/CMakeLists.txt

@@ -11,6 +11,7 @@ add_library(eval_shared STATIC EXCLUDE_FROM_ALL
         "scf.hpp"
         "scf.cpp"
 )
+set_target_properties(eval_shared PROPERTIES CXX_SCAN_FOR_MODULES OFF)
 target_link_libraries(eval_shared PUBLIC SeQuant)
 target_include_directories(eval_shared PUBLIC "${CMAKE_CURRENT_SOURCE_DIR}")
 
@@ -20,6 +21,7 @@ if (SEQUANT_HAS_TILEDARRAY)
             "ta/scf_ta.hpp"
             "ta/main.cpp"
     )
+    set_target_properties(eval_ta PROPERTIES CXX_SCAN_FOR_MODULES OFF)
     target_link_libraries(eval_ta PRIVATE eval_shared tiledarray)
 
     set(test_name "sequant/integration/eval_ta")
@@ -38,6 +40,7 @@ if (SEQUANT_HAS_BTAS)
             "btas/scf_btas.hpp"
             "btas/main.cpp"
     )
+    set_target_properties(eval_btas PROPERTIES CXX_SCAN_FOR_MODULES OFF)
     target_link_libraries(eval_btas PRIVATE eval_shared BTAS::BTAS)
 
     set(test_name "sequant/integration/eval_btas")
@@ -56,6 +59,7 @@ if (SEQUANT_HAS_TAPP)
             "tapp/scf_tapp.hpp"
             "tapp/main.cpp"
     )
+    set_target_properties(eval_tapp PROPERTIES CXX_SCAN_FOR_MODULES OFF)
     target_link_libraries(eval_tapp PRIVATE eval_shared tapp::reference)
 
     set(test_name "sequant/integration/eval_tapp")

tests/unit/CMakeLists.txt

@@ -28,6 +28,7 @@ set(symb_test_sources
 )
 
 add_library(unit_tests-sequant-symb-obj OBJECT ${symb_test_sources})
+set_target_properties(unit_tests-sequant-symb-obj PROPERTIES CXX_SCAN_FOR_MODULES OFF)
 target_link_libraries(unit_tests-sequant-symb-obj
     PUBLIC SeQuant::symb SeQuant::bliss
     PRIVATE Catch2::Catch2 dtl::dtl)
@@ -42,6 +43,7 @@ set(eval_test_sources
     "test_eval_node.cpp"
 )
 add_library(unit_tests-sequant-eval-obj OBJECT ${eval_test_sources})
+set_target_properties(unit_tests-sequant-eval-obj PROPERTIES CXX_SCAN_FOR_MODULES OFF)
 target_link_libraries(unit_tests-sequant-eval-obj
     PUBLIC SeQuant::eval
     PRIVATE Catch2::Catch2 dtl::dtl)
@@ -56,6 +58,7 @@ set(optimize_test_sources
     "test_optimize.cpp"
 )
 add_library(unit_tests-sequant-optimize-obj OBJECT ${optimize_test_sources})
+set_target_properties(unit_tests-sequant-optimize-obj PROPERTIES CXX_SCAN_FOR_MODULES OFF)
 target_link_libraries(unit_tests-sequant-optimize-obj
     PUBLIC SeQuant::optimize SeQuant::bliss
     PRIVATE Catch2::Catch2 dtl::dtl)
@@ -71,6 +74,7 @@ set(export_test_sources
     "test_export_python.cpp"
 )
 add_library(unit_tests-sequant-export-obj OBJECT ${export_test_sources})
+set_target_properties(unit_tests-sequant-export-obj PROPERTIES CXX_SCAN_FOR_MODULES OFF)
 target_link_libraries(unit_tests-sequant-export-obj
     PUBLIC SeQuant::export SeQuant::optimize
     PRIVATE Catch2::Catch2 dtl::dtl Eigen3::Eigen)
@@ -88,6 +92,7 @@ set(mbpt_test_sources
 )
 
 add_library(unit_tests-sequant-mbpt-obj OBJECT ${mbpt_test_sources})
+set_target_properties(unit_tests-sequant-mbpt-obj PROPERTIES CXX_SCAN_FOR_MODULES OFF)
 target_link_libraries(unit_tests-sequant-mbpt-obj
     PUBLIC SeQuant::mbpt
     PRIVATE Catch2::Catch2 dtl::dtl)
@@ -103,6 +108,7 @@ if (SEQUANT_HAS_TILEDARRAY)
         "test_cache_manager.cpp"
     )
     add_library(unit_tests-sequant-eval-ta-obj OBJECT ${eval_ta_test_sources})
+    set_target_properties(unit_tests-sequant-eval-ta-obj PROPERTIES CXX_SCAN_FOR_MODULES OFF)
     target_link_libraries(unit_tests-sequant-eval-ta-obj
         PUBLIC SeQuant::eval::ta SeQuant::mbpt
         PRIVATE Catch2::Catch2 dtl::dtl)
@@ -122,6 +128,7 @@ if (SEQUANT_HAS_BTAS)
         list(APPEND eval_btas_test_sources "test_cache_manager.cpp")
     endif()
     add_library(unit_tests-sequant-eval-btas-obj OBJECT ${eval_btas_test_sources})
+    set_target_properties(unit_tests-sequant-eval-btas-obj PROPERTIES CXX_SCAN_FOR_MODULES OFF)
     target_link_libraries(unit_tests-sequant-eval-btas-obj
         PUBLIC SeQuant::eval::btas SeQuant::mbpt
         PRIVATE Catch2::Catch2 dtl::dtl)
@@ -137,6 +144,7 @@ endif()
 if (SEQUANT_HAS_TAPP)
     set(eval_tapp_test_sources "test_eval_tapp.cpp")
     add_library(unit_tests-sequant-eval-tapp-obj OBJECT ${eval_tapp_test_sources})
+    set_target_properties(unit_tests-sequant-eval-tapp-obj PROPERTIES CXX_SCAN_FOR_MODULES OFF)
     target_link_libraries(unit_tests-sequant-eval-tapp-obj
         PUBLIC SeQuant::eval::tapp SeQuant::mbpt
         PRIVATE Catch2::Catch2 dtl::dtl)
@@ -155,6 +163,7 @@ endif()
 add_executable(unit_tests-sequant ${BUILD_BY_DEFAULT}
     "test_main.cpp"
 )
+set_target_properties(unit_tests-sequant PROPERTIES CXX_SCAN_FOR_MODULES OFF)
 target_link_libraries(unit_tests-sequant PRIVATE
     unit_tests-sequant-symb-obj
     unit_tests-sequant-eval-obj

utilities/CMakeLists.txt

@@ -5,6 +5,7 @@ set(EXECUTABLE_SOURCES
 foreach(current IN LISTS EXECUTABLE_SOURCES)
     string(REGEX REPLACE "\\.cpp$" "" name "${current}")
     add_executable(${name} ${current})
+    set_target_properties(${name} PROPERTIES CXX_SCAN_FOR_MODULES OFF)
     target_link_libraries(${name} SeQuant)
 
     target_set_warning_flags("${name}")

utilities/external-interface/CMakeLists.txt

@@ -9,6 +9,7 @@ add_executable(external_interface
     processing.cpp
     utils.cpp
 )
+set_target_properties(external_interface PROPERTIES CXX_SCAN_FOR_MODULES OFF)
 
 target_link_libraries(external_interface
     PRIVATE