From 0c929e1721cdf09f5445f04ca618c42b1c8a7198 Mon Sep 17 00:00:00 2001
From: Florian Albrechtskirchinger <falbrechtskirchinger@gmail.com>
Date: Mon, 25 Apr 2022 23:47:33 +0200
Subject: [PATCH] CI: add legacy discarded value comparison

---
 .github/workflows/ubuntu.yml |  2 +-
 CMakeLists.txt               | 24 +++++++++++++++---------
 cmake/ci.cmake               | 19 +++++++++++++++++--
 3 files changed, 33 insertions(+), 12 deletions(-)

diff --git a/.github/workflows/ubuntu.yml b/.github/workflows/ubuntu.yml
index 4d037e060..39098e4d7 100644
--- a/.github/workflows/ubuntu.yml
+++ b/.github/workflows/ubuntu.yml
@@ -48,7 +48,7 @@ jobs:
     container: ghcr.io/nlohmann/json-ci:v2.3.0
     strategy:
       matrix:
-        target: [ci_test_diagnostics, ci_test_noexceptions, ci_test_noimplicitconversions]
+        target: [ci_test_diagnostics, ci_test_noexceptions, ci_test_noimplicitconversions, ci_test_legacycomparison]
     steps:
       - uses: actions/checkout@v3
       - name: cmake
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 8f65d9a32..632e6dec2 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -37,13 +37,14 @@ if(${MAIN_PROJECT} AND (${CMAKE_VERSION} VERSION_EQUAL 3.13 OR ${CMAKE_VERSION}
 else()
     set(JSON_BuildTests_INIT OFF)
 endif()
-option(JSON_BuildTests          "Build the unit tests when BUILD_TESTING is enabled." ${JSON_BuildTests_INIT})
-option(JSON_CI                  "Enable CI build targets." OFF)
-option(JSON_Diagnostics         "Use extended diagnostic messages." OFF)
-option(JSON_ImplicitConversions "Enable implicit conversions." ON)
-option(JSON_Install             "Install CMake targets during install step." ${MAIN_PROJECT})
-option(JSON_MultipleHeaders     "Use non-amalgamated version of the library." OFF)
-option(JSON_SystemInclude       "Include as system headers (skip for clang-tidy)." OFF)
+option(JSON_BuildTests                     "Build the unit tests when BUILD_TESTING is enabled." ${JSON_BuildTests_INIT})
+option(JSON_CI                             "Enable CI build targets." OFF)
+option(JSON_Diagnostics                    "Use extended diagnostic messages." OFF)
+option(JSON_ImplicitConversions            "Enable implicit conversions." ON)
+option(JSON_LegacyDiscardedValueComparison "Enable legacy discarded value comparison." OFF)           
+option(JSON_Install                        "Install CMake targets during install step." ${MAIN_PROJECT})
+option(JSON_MultipleHeaders                "Use non-amalgamated version of the library." OFF)
+option(JSON_SystemInclude                  "Include as system headers (skip for clang-tidy)." OFF)
 
 if (JSON_CI)
     include(ci)
@@ -77,6 +78,10 @@ if (NOT JSON_ImplicitConversions)
     message(STATUS "Implicit conversions are disabled")
 endif()
 
+if (JSON_LegacyDiscardedValueComparison)
+    message(STATUS "Legacy discarded value comparison enabled")
+endif()
+
 if (JSON_Diagnostics)
     message(STATUS "Diagnostics enabled")
 endif()
@@ -100,8 +105,9 @@ endif()
 target_compile_definitions(
     ${NLOHMANN_JSON_TARGET_NAME}
     INTERFACE
-    JSON_USE_IMPLICIT_CONVERSIONS=$<BOOL:${JSON_ImplicitConversions}>
-    JSON_DIAGNOSTICS=$<BOOL:${JSON_Diagnostics}>
+    $<$<NOT:$<BOOL:${JSON_ImplicitConversions}>>:JSON_USE_IMPLICIT_CONVERSIONS=0>
+    $<$<BOOL:${JSON_Diagnostics}>:JSON_DIAGNOSTICS=1>
+    $<$<BOOL:${JSON_LegacyDiscardedValueComparison}>:JSON_USE_LEGACY_DISCARDED_VALUE_COMPARISON=1>
 )
 
 target_include_directories(
diff --git a/cmake/ci.cmake b/cmake/ci.cmake
index 56a80c066..ed26e02b5 100644
--- a/cmake/ci.cmake
+++ b/cmake/ci.cmake
@@ -498,6 +498,20 @@ add_custom_target(ci_test_diagnostics
     COMMENT "Compile and test with improved diagnostics enabled"
 )
 
+###############################################################################
+# Enable legacy discarded value comparison.
+###############################################################################
+
+add_custom_target(ci_test_legacycomparison
+    COMMAND CXX=${CLANG_TOOL} ${CMAKE_COMMAND}
+    -DCMAKE_BUILD_TYPE=Debug -GNinja
+    -DJSON_BuildTests=ON -DJSON_MultipleHeaders=ON -DJSON_LegacyDiscardedValueComparison=ON
+    -S${PROJECT_SOURCE_DIR} -B${PROJECT_BINARY_DIR}/build_legacycomparison
+    COMMAND ${CMAKE_COMMAND} --build ${PROJECT_BINARY_DIR}/build_legacycomparison
+    COMMAND cd ${PROJECT_BINARY_DIR}/build_legacycomparison && ${CMAKE_CTEST_COMMAND} --parallel ${N} --output-on-failure
+    COMMENT "Compile and test with legacy discarded value comparison enabled"
+)
+
 ###############################################################################
 # Coverage.
 ###############################################################################
@@ -797,8 +811,9 @@ endfunction()
 ci_get_cmake(3.1.0 CMAKE_3_1_0_BINARY)
 ci_get_cmake(3.13.0 CMAKE_3_13_0_BINARY)
 
-set(JSON_CMAKE_FLAGS_3_1_0 "JSON_Install;JSON_MultipleHeaders;JSON_ImplicitConversions;JSON_Valgrind;JSON_Diagnostics;JSON_SystemInclude")
-set(JSON_CMAKE_FLAGS_3_13_0 "JSON_BuildTests")
+set(JSON_CMAKE_FLAGS_3_1_0 JSON_Diagnostics JSON_ImplicitConversions JSON_LegacyDiscardedValueComparison 
+    JSON_Install JSON_MultipleHeaders JSON_SystemInclude JSON_Valgrind)
+set(JSON_CMAKE_FLAGS_3_13_0 JSON_BuildTests)
 
 function(ci_add_cmake_flags_targets flag min_version)
     string(TOLOWER "ci_cmake_flag_${flag}" flag_target)