From cf2a896bcda378f90dd0f70b7b89fa3305513adb Mon Sep 17 00:00:00 2001
From: Niels Lohmann <mail@nlohmann.me>
Date: Wed, 20 Oct 2021 13:03:08 +0200
Subject: [PATCH] :alembic: add C++17 copies of the test binaries

---
 test/CMakeLists.txt | 55 ++++++++++++++++++++++++++-------------------
 1 file changed, 32 insertions(+), 23 deletions(-)

diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index 9342faace..76af0f1f8 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -52,6 +52,13 @@ endif()
 # one executable for each unit test file
 #############################################################################
 
+# check if compiler supports C++17
+foreach(feature ${CMAKE_CXX_COMPILE_FEATURES})
+    if (${feature} STREQUAL cxx_std_17)
+        set(compiler_supports_cpp_17 TRUE)
+    endif()
+endforeach()
+
 file(GLOB files src/unit-*.cpp)
 
 foreach(file ${files})
@@ -69,30 +76,32 @@ foreach(file ${files})
     target_link_libraries(${testcase} PRIVATE ${NLOHMANN_JSON_TARGET_NAME})
 
     # add a copy with C++17 compilation
-    file(READ ${file} FILE_CONTENT)
-    string(FIND "${FILE_CONTENT}" "JSON_HAS_CPP_17" CPP_17_FOUND)
-    if(NOT ${CPP_17_FOUND} EQUAL -1)
-        add_executable(${testcase}_cpp17 $<TARGET_OBJECTS:doctest_main> ${file})
-        target_compile_definitions(${testcase}_cpp17 PRIVATE DOCTEST_CONFIG_SUPER_FAST_ASSERTS)
-        target_compile_options(${testcase}_cpp17 PRIVATE
-            $<$<CXX_COMPILER_ID:MSVC>:/EHsc;$<$<CONFIG:Release>:/Od>>
-            $<$<NOT:$<CXX_COMPILER_ID:MSVC>>:-Wno-deprecated;-Wno-float-equal>
-            $<$<CXX_COMPILER_ID:GNU>:-Wno-deprecated-declarations>
-        )
-        target_include_directories(${testcase}_cpp17 PRIVATE ${CMAKE_BINARY_DIR}/include thirdparty/doctest thirdparty/fifo_map)
-        target_link_libraries(${testcase}_cpp17 PRIVATE ${NLOHMANN_JSON_TARGET_NAME})
-        set_target_properties(${testcase}_cpp17 PROPERTIES CXX_STANDARD 17)
+    if (compiler_supports_cpp_17)
+        file(READ ${file} FILE_CONTENT)
+        string(FIND "${FILE_CONTENT}" "JSON_HAS_CPP_17" CPP_17_FOUND)
+        if(NOT ${CPP_17_FOUND} EQUAL -1)
+            add_executable(${testcase}_cpp17 $<TARGET_OBJECTS:doctest_main> ${file})
+            target_compile_definitions(${testcase}_cpp17 PRIVATE DOCTEST_CONFIG_SUPER_FAST_ASSERTS)
+            target_compile_options(${testcase}_cpp17 PRIVATE
+                $<$<CXX_COMPILER_ID:MSVC>:/EHsc;$<$<CONFIG:Release>:/Od>>
+                $<$<NOT:$<CXX_COMPILER_ID:MSVC>>:-Wno-deprecated;-Wno-float-equal>
+                $<$<CXX_COMPILER_ID:GNU>:-Wno-deprecated-declarations>
+            )
+            target_include_directories(${testcase}_cpp17 PRIVATE ${CMAKE_BINARY_DIR}/include thirdparty/doctest thirdparty/fifo_map)
+            target_link_libraries(${testcase}_cpp17 PRIVATE ${NLOHMANN_JSON_TARGET_NAME})
+            target_compile_features(${testcase}_cpp17 PRIVATE cxx_std_17)
 
-        if (JSON_FastTests)
-            add_test(NAME "${testcase}_cpp17"
-                COMMAND ${testcase}_cpp17 ${DOCTEST_TEST_FILTER}
-                WORKING_DIRECTORY ${CMAKE_SOURCE_DIR}
-            )
-        else()
-            add_test(NAME "${testcase}_cpp17"
-                COMMAND ${testcase}_cpp17 ${DOCTEST_TEST_FILTER} --no-skip
-                WORKING_DIRECTORY ${CMAKE_SOURCE_DIR}
-            )
+            if (JSON_FastTests)
+                add_test(NAME "${testcase}_cpp17"
+                    COMMAND ${testcase}_cpp17 ${DOCTEST_TEST_FILTER}
+                    WORKING_DIRECTORY ${CMAKE_SOURCE_DIR}
+                )
+            else()
+                add_test(NAME "${testcase}_cpp17"
+                    COMMAND ${testcase}_cpp17 ${DOCTEST_TEST_FILTER} --no-skip
+                    WORKING_DIRECTORY ${CMAKE_SOURCE_DIR}
+                )
+            endif()
         endif()
     endif()