Add build step for ICPC (with fixes)

.github/workflows/ubuntu.yml

@@ -112,3 +112,15 @@ jobs:
         run: cmake -S . -B build -DJSON_CI=On
       - name: build
         run: cmake --build build --target ci_cuda_example
+
+  ci_icpc:
+    runs-on: ubuntu-latest
+    container: ghcr.io/nlohmann/json-ci:v2.2.0
+    steps:
+      - uses: actions/checkout@v2
+      - name: cmake
+        run: cmake -S . -B build -DJSON_CI=On
+      - name: build
+        run: |
+          . /opt/intel/oneapi/setvars.sh
+          cmake --build build --target ci_icpc

README.md

@@ -1083,18 +1083,6 @@ The following compilers are currently used in continuous integration at [AppVeyo
 | Apple Clang 12.0.0 (clang-1200.0.32.27); Xcode 12.2                                                    | macOS 10.15.7      | GitHub Actions |
 | Apple Clang 12.0.0 (clang-1200.0.32.28); Xcode 12.3                                                    | macOS 10.15.7      | GitHub Actions |
 | Apple Clang 12.0.0 (clang-1200.0.32.29); Xcode 12.4                                                    | macOS 10.15.7      | GitHub Actions |
-| GCC 4.8.5 (Ubuntu 4.8.5-4ubuntu2)                                                                      | Ubuntu 20.04.3 LTS | GitHub Actions |
-| GCC 4.9.3 (Ubuntu 4.9.3-13ubuntu2)                                                                     | Ubuntu 20.04.3 LTS | GitHub Actions |
-| GCC 5.4.0 (Ubuntu 5.4.0-6ubuntu1~16.04.12)                                                             | Ubuntu 20.04.3 LTS | GitHub Actions |
-| GCC 6.4.0 (Ubuntu 6.4.0-17ubuntu1)                                                                     | Ubuntu 20.04.3 LTS | GitHub Actions |
-| GCC 7.5.0 (Ubuntu 7.5.0-6ubuntu2)                                                                      | Ubuntu 20.04.3 LTS | GitHub Actions |
-| GCC 8.1.0 (x86_64-posix-seh-rev0, Built by MinGW-W64 project)                                          | Windows-10.0.17763 | GitHub Actions |
-| GCC 8.1.0 (i686-posix-dwarf-rev0, Built by MinGW-W64 project)                                          | Windows-10.0.17763 | GitHub Actions |
-| GCC 8.4.0 (Ubuntu 8.4.0-3ubuntu2)                                                                      | Ubuntu 20.04.3 LTS | GitHub Actions |
-| GCC 9.3.0 (Ubuntu 9.3.0-17ubuntu1~20.04)                                                               | Ubuntu 20.04.3 LTS | GitHub Actions |
-| GCC 10.2.0 (Ubuntu 10.2.0-5ubuntu1~20.04)                                                              | Ubuntu 20.04.3 LTS | GitHub Actions |
-| GCC 11.1.0                                                                                             | Ubuntu (aarch64)   | Drone CI       |
-| GCC 12.0.0 20211219 (experimental)                                                                     | Ubuntu 20.04.3 LTS | GitHub Actions |
 | Clang 3.5.2 (3.5.2-3ubuntu1)                                                                           | Ubuntu 20.04.3 LTS | GitHub Actions |
 | Clang 3.6.2 (3.6.2-3ubuntu2)                                                                           | Ubuntu 20.04.3 LTS | GitHub Actions |
 | Clang 3.7.1 (3.7.1-2ubuntu2)                                                                           | Ubuntu 20.04.3 LTS | GitHub Actions |
@@ -1115,6 +1103,19 @@ The following compilers are currently used in continuous integration at [AppVeyo
 | Clang 13.0.1 (13.0.1-++20211015123032+cf15ccdeb6d5-1exp120211015003613.5)                              | Ubuntu 20.04.3 LTS | GitHub Actions |
 | Clang 14.0.0 (14.0.0-++20211221052852+55c71c9eac9b-1exp120211221172954.95)                             | Ubuntu 20.04.3 LTS | GitHub Actions |
 | Clang 15.0.0 (15.0.0-++20220403052648+896770c9a92e-1~exp1~20220403172744.209)                          | Ubuntu 20.04.3 LTS | GitHub Actions |
+| GCC 4.8.5 (Ubuntu 4.8.5-4ubuntu2)                                                                      | Ubuntu 20.04.3 LTS | GitHub Actions |
+| GCC 4.9.3 (Ubuntu 4.9.3-13ubuntu2)                                                                     | Ubuntu 20.04.3 LTS | GitHub Actions |
+| GCC 5.4.0 (Ubuntu 5.4.0-6ubuntu1~16.04.12)                                                             | Ubuntu 20.04.3 LTS | GitHub Actions |
+| GCC 6.4.0 (Ubuntu 6.4.0-17ubuntu1)                                                                     | Ubuntu 20.04.3 LTS | GitHub Actions |
+| GCC 7.5.0 (Ubuntu 7.5.0-6ubuntu2)                                                                      | Ubuntu 20.04.3 LTS | GitHub Actions |
+| GCC 8.1.0 (i686-posix-dwarf-rev0, Built by MinGW-W64 project)                                          | Windows-10.0.17763 | GitHub Actions |
+| GCC 8.1.0 (x86_64-posix-seh-rev0, Built by MinGW-W64 project)                                          | Windows-10.0.17763 | GitHub Actions |
+| GCC 8.4.0 (Ubuntu 8.4.0-3ubuntu2)                                                                      | Ubuntu 20.04.3 LTS | GitHub Actions |
+| GCC 9.3.0 (Ubuntu 9.3.0-17ubuntu1~20.04)                                                               | Ubuntu 20.04.3 LTS | GitHub Actions |
+| GCC 10.2.0 (Ubuntu 10.2.0-5ubuntu1~20.04)                                                              | Ubuntu 20.04.3 LTS | GitHub Actions |
+| GCC 11.1.0                                                                                             | Ubuntu (aarch64)   | Drone CI       |
+| GCC 12.0.0 20211219 (experimental)                                                                     | Ubuntu 20.04.3 LTS | GitHub Actions |
+| Intel C++ Compiler 2021.5.0.20211109                                                                   | Ubuntu 20.04.3 LTS | GitHub Actions |
 | NVCC 11.0.221                                                                                          | Ubuntu 20.04.3 LTS | GitHub Actions |
 | Visual Studio 14 2015 MSVC 19.0.24241.7 (Build Engine version 14.0.25420.1)                            | Windows-6.3.9600   | AppVeyor       |
 | Visual Studio 15 2017 MSVC 19.16.27035.0 (Build Engine version 15.9.21+g9802d43bc3 for .NET Framework) | Windows-10.0.14393 | AppVeyor       |

cmake/ci.cmake

@@ -877,6 +877,21 @@ add_custom_target(ci_cuda_example
     COMMAND ${CMAKE_COMMAND} --build ${PROJECT_BINARY_DIR}/build_cuda_example
 )
 
+###############################################################################
+# Intel C++ Compiler
+###############################################################################
+
+add_custom_target(ci_icpc
+    COMMAND ${CMAKE_COMMAND}
+        -DCMAKE_BUILD_TYPE=Debug -GNinja
+        -DCMAKE_C_COMPILER=icc -DCMAKE_CXX_COMPILER=icpc
+        -DJSON_BuildTests=ON -DJSON_FastTests=ON
+        -S${PROJECT_SOURCE_DIR} -B${PROJECT_BINARY_DIR}/build_icpc
+    COMMAND ${CMAKE_COMMAND} --build ${PROJECT_BINARY_DIR}/build_icpc
+    COMMAND cd ${PROJECT_BINARY_DIR}/build_icpc && ${CMAKE_CTEST_COMMAND} --parallel ${N} --exclude-regex "test-unicode" --output-on-failure
+    COMMENT "Compile and test with ICPC"
+)
+
 ###############################################################################
 # Clean up all generated files.
 ###############################################################################

include/nlohmann/detail/meta/type_traits.hpp

@@ -347,8 +347,15 @@ struct is_compatible_string_type
 template<typename BasicJsonType, typename ConstructibleStringType>
 struct is_constructible_string_type
 {
+    // launder type through decltype() to fix compilation failure on ICPC
+#ifdef __INTEL_COMPILER
+    using laundered_type = decltype(std::declval<ConstructibleStringType>());
+#else
+    using laundered_type = ConstructibleStringType;
+#endif
+
     static constexpr auto value =
-        is_constructible<ConstructibleStringType,
+        is_constructible<laundered_type,
         typename BasicJsonType::string_t>::value;
 };
 

single_include/nlohmann/json.hpp

@@ -3482,8 +3482,15 @@ struct is_compatible_string_type
 template<typename BasicJsonType, typename ConstructibleStringType>
 struct is_constructible_string_type
 {
+    // launder type through decltype() to fix compilation failure on ICPC
+#ifdef __INTEL_COMPILER
+    using laundered_type = decltype(std::declval<ConstructibleStringType>());
+#else
+    using laundered_type = ConstructibleStringType;
+#endif
+
     static constexpr auto value =
-        is_constructible<ConstructibleStringType,
+        is_constructible<laundered_type,
         typename BasicJsonType::string_t>::value;
 };
 

tests/CMakeLists.txt

@@ -49,8 +49,12 @@ target_compile_options(test_main PUBLIC
     # https://github.com/nlohmann/json/issues/1114
     $<$<CXX_COMPILER_ID:MSVC>:/bigobj> $<$<BOOL:${MINGW}>:-Wa,-mbig-obj>
 
+    # https://github.com/nlohmann/json/pull/3229
+    $<$<CXX_COMPILER_ID:Intel>:-diag-disable=2196>
+
     $<$<NOT:$<CXX_COMPILER_ID:MSVC>>:-Wno-deprecated;-Wno-float-equal>
     $<$<CXX_COMPILER_ID:GNU>:-Wno-deprecated-declarations>
+    $<$<CXX_COMPILER_ID:Intel>:-diag-disable=1786>
 )
 target_include_directories(test_main PUBLIC
     thirdparty/doctest

tests/src/unit-regression2.cpp

@@ -512,12 +512,15 @@ TEST_CASE("regression tests 2")
 
     SECTION("issue #1647 - compile error when deserializing enum if both non-default from_json and non-member operator== exists for other type")
     {
+        // does not compile on ICPC when targeting C++20
+#if !(defined(__INTEL_COMPILER) && __cplusplus >= 202000)
         {
             json j;
             NonDefaultFromJsonStruct x(j);
             NonDefaultFromJsonStruct y;
             CHECK(x == y);
         }
+#endif
 
         auto val = nlohmann::json("one").get<for_1647>();
         CHECK(val == for_1647::one);
@@ -793,8 +796,8 @@ TEST_CASE("regression tests 2")
         const auto j_path = j.get<nlohmann::detail::std_fs::path>();
         CHECK(j_path == text_path);
 
-#if !defined(_MSC_VER) && !(defined(__GNUC__) && __GNUC__ == 8 && __GNUC_MINOR__ < 4)
-        // works everywhere but on MSVC and GCC <8.4
+#if defined(__clang__) || ((defined(__GNUC__) && !defined(__INTEL_COMPILER)) && (__GNUC__ > 8 || (__GNUC__ == 8 && __GNUC_MINOR__ >= 4)))
+        // only known to work on Clang and GCC >=8.4
         CHECK_THROWS_WITH_AS(nlohmann::detail::std_fs::path(json(1)), "[json.exception.type_error.302] type must be string, but is number", json::type_error);
 #endif
     }

tests/src/unit-wstring.cpp

@@ -32,6 +32,8 @@ SOFTWARE.
 #include <nlohmann/json.hpp>
 using nlohmann::json;
 
+// ICPC errors out on multibyte character sequences in source files
+#ifndef __INTEL_COMPILER
 namespace
 {
 bool wstring_is_utf16();
@@ -115,3 +117,4 @@ TEST_CASE("wide strings")
         }
     }
 }
+#endif