⏪ re-add GCC 4.8

.github/workflows/ubuntu.yml

@@ -59,13 +59,12 @@ jobs:
 
   ci_cmake_options:
     runs-on: ubuntu-latest
+    container: ghcr.io/nlohmann/json-ci:v2.4.0
     strategy:
       matrix:
         target: [ci_test_diagnostics, ci_test_noexceptions, ci_test_noimplicitconversions, ci_test_legacycomparison, ci_test_noglobaludls]
     steps:
       - uses: actions/checkout@v3
-      - name: Get latest CMake and ninja
-        uses: lukka/get-cmake@latest
       - name: Run CMake
         run: cmake -S . -B build -DJSON_CI=On
       - name: Build
@@ -121,6 +120,19 @@ jobs:
       - name: Build
         run: cmake --build build --target ci_test_compiler_default
 
+  ci_test_compilers:
+    runs-on: ubuntu-latest
+    container: ghcr.io/nlohmann/json-ci:v2.4.0
+    strategy:
+      matrix:
+        compiler: [g++-4.8]
+    steps:
+      - uses: actions/checkout@v3
+      - name: Run CMake
+        run: cmake -S . -B build -DJSON_CI=On
+      - name: Build
+        run: cmake --build build --target ci_test_compiler_${{ matrix.compiler }}
+
   ci_test_standards:
     runs-on: ubuntu-latest
     container: ghcr.io/nlohmann/json-ci:v2.4.0

cmake/ci.cmake

@@ -905,6 +905,30 @@ add_custom_target(ci_cmake_flags
 # Use more installed compilers.
 ###############################################################################
 
+foreach(COMPILER g++-4.8 g++-4.9 g++-5 g++-6 g++-7 g++-8 g++-9 g++-10 g++-11 clang++-3.5 clang++-3.6 clang++-3.7 clang++-3.8 clang++-3.9 clang++-4.0 clang++-5.0 clang++-6.0 clang++-7 clang++-8 clang++-9 clang++-10 clang++-11 clang++-12 clang++-13 clang++-14)
+    find_program(COMPILER_TOOL NAMES ${COMPILER})
+    if (COMPILER_TOOL)
+        if ("${COMPILER}" STREQUAL "clang++-9")
+            # fix for https://github.com/nlohmann/json/pull/3101#issuecomment-998788786 / https://stackoverflow.com/a/64051725/266378
+            set(ADDITIONAL_FLAGS "-DCMAKE_CXX_FLAGS=--gcc-toolchain=/root/gcc/9")
+        else()
+            unset(ADDITIONAL_FLAGS)
+        endif()
+
+        add_custom_target(ci_test_compiler_${COMPILER}
+            COMMAND CXX=${COMPILER} ${CMAKE_COMMAND}
+                -DCMAKE_BUILD_TYPE=Debug -GNinja
+                -DJSON_BuildTests=ON -DJSON_FastTests=ON
+                -S${PROJECT_SOURCE_DIR} -B${PROJECT_BINARY_DIR}/build_compiler_${COMPILER}
+                ${ADDITIONAL_FLAGS}
+            COMMAND ${CMAKE_COMMAND} --build ${PROJECT_BINARY_DIR}/build_compiler_${COMPILER}
+            COMMAND cd ${PROJECT_BINARY_DIR}/build_compiler_${COMPILER} && ${CMAKE_CTEST_COMMAND} --parallel ${N} --exclude-regex "test-unicode" --output-on-failure
+            COMMENT "Compile and test with ${COMPILER}"
+        )
+    endif()
+    unset(COMPILER_TOOL CACHE)
+endforeach()
+
 add_custom_target(ci_test_compiler_default
     COMMAND ${CMAKE_COMMAND}
         -DCMAKE_BUILD_TYPE=Debug -GNinja