Add build step for ICPC

[nlohmann]

This PR adds a CI build step for the Intel C++ Compiler

[coveralls]

Coverage remained the same at 100.0% when pulling f9dfd63 on icpc into b21c345 on develop.

[nlohmann]

ICPC fails to build the test suite.

• https://github.com/nlohmann/json/runs/4665922491?check_suite_focus=true failed with

/__w/json/json/test/src/unit-regression2.cpp(810): error: more than one instance of constructor "std::filesystem::__cxx11::path::path" matches the argument list:
            function "std::filesystem::__cxx11::path::path(std::filesystem::__cxx11::path &&) noexcept"
            function "std::filesystem::__cxx11::path::path(std::filesystem::__cxx11::path::string_type &&, std::filesystem::__cxx11::path::format)"
            argument types are: (json)
          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);
          ^
/usr/include/c++/9/bits/fs_path.h(473): note: this candidate was rejected because mismatch in count of arguments
      path(basic_string_view<value_type> __str, _Type __type)
      ^
/usr/include/c++/9/bits/fs_path.h(213): note: this candidate was rejected because mismatch in count of arguments
        path(_InputIterator __first, _InputIterator __last, const locale& __loc,
        ^
/usr/include/c++/9/bits/fs_path.h(205): note: this candidate was rejected because mismatch in count of arguments
        path(_Source const& __source, const locale& __loc, format = auto_format)
        ^
/usr/include/c++/9/bits/fs_path.h(198): note: this candidate was rejected because mismatch in count of arguments
        path(_InputIterator __first, _InputIterator __last, format = auto_format)
        ^
/usr/include/c++/9/bits/fs_path.h(191): note: this candidate was rejected because at least one template argument could not be deduced
        path(_Source const& __source, format = auto_format)
        ^

• Switching off std::filesystem tests with -DCMAKE_CXX_FLAGS="-DJSON_HAS_FILESYSTEM=0 -DJSON_HAS_EXPERIMENTAL_FILESYSTEM=0" fails (https://github.com/nlohmann/json/runs/4666752017?check_suite_focus=true) with

In file included from /__w/json/json/test/src/unit-algorithms.cpp(32):
/__w/json/json/single_include/nlohmann/json.hpp(3821): error: this operator is not allowed in a constant expression
  #elif JSON_HAS_FILESYSTEM
        ^

In file included from /__w/json/json/test/src/unit-algorithms.cpp(32):
/__w/json/json/single_include/nlohmann/json.hpp(4254): error: this operator is not allowed in a constant expression
  #if JSON_HAS_FILESYSTEM || JSON_HAS_EXPERIMENTAL_FILESYSTEM
      ^

In file included from /__w/json/json/test/src/unit-algorithms.cpp(32):
/__w/json/json/single_include/nlohmann/json.hpp(4507): error: this operator is not allowed in a constant expression
  #elif JSON_HAS_FILESYSTEM
        ^

In file included from /__w/json/json/test/src/unit-algorithms.cpp(32):
/__w/json/json/single_include/nlohmann/json.hpp(4887): error: this operator is not allowed in a constant expression
  #if JSON_HAS_FILESYSTEM || JSON_HAS_EXPERIMENTAL_FILESYSTEM
      ^

[falbrechtskirchinger]

Have a look at #3377. I had to disable the CHECK_THROWS_WITH_AS in #3379.

[nlohmann]

Have a look at #3377. I had to disable the CHECK_THROWS_WITH_AS in #3379.

Thanks for pointing this out. I am now confused as well. If I would just comment out the test, I'm afraid that I would ignore something not working...

[falbrechtskirchinger]

Adding $<$<CXX_COMPILER_ID:Intel>:-diag-disable=2196> or $<$<CXX_COMPILER_ID:Intel>:-wd2196> (deprecated) should get rid of

warning #2196: routine is both "inline" and "noinline"

if that is still an issue with current doctest.

[falbrechtskirchinger]

I'd suggest using the literal style block scalar | over the flow style one > for multiline commands:

        run: |
          . /opt/intel/oneapi/setvars.sh
          cmake --build build --target ci_icpc

[falbrechtskirchinger]

This may need a version check. It's -wd2196 for older versions but I'm not familiar with ICPC, so I don't know since when the new flag is available. 🤷‍♂️

Also, 1786 to suppress deprecation warnings.

[falbrechtskirchinger]

I couldn't find a version number in the documentation.

[falbrechtskirchinger]

Appears as -DJSON_HAS_FILESYSTEM=0\ -DJSON_HAS_EXPERIMENTAL_FILESYSTEM=0 on the commandline and results in:

/__w/json/json/single_include/nlohmann/json.hpp(4116): error: this operator is not allowed in a constant expression
  #elif JSON_HAS_FILESYSTEM

Remove? Don't know why <filesystem> detection was an issue on ICPC but might have been fixed by now?
Edit: Remove. Works (almost; see below) without.

[falbrechtskirchinger]

Intel needs to be excluded here as well. :-(

#if JSON_HAS_FILESYSTEM || JSON_HAS_EXPERIMENTAL_FILESYSTEM
    // JSON_HAS_CPP_17 (do not remove; see note at top of file)
    SECTION("issue #3070 - Version 3.10.3 breaks backward-compatibility with 3.10.2 ")
    {
        nlohmann::detail::std_fs::path text_path("/tmp/text.txt");
        json j(text_path);

        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
        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
    }
#endif

Maybe this condition should just be changed to:

#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

Edit: We don't have JSON_HEDLEY_GNUC_VERSION_CHECK in the test suite. Fixed.
Edit 2: Condition was still not correct. Hopefully now.

[falbrechtskirchinger]

Another issue:

    SECTION("issue #1647 - compile error when deserializing enum if both non-default from_json and non-member operator== exists for other type")
    {
#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);
        json j = val;
    }

Test fails to compile on ICPC without the preprocessor guard when targeting C++20.

/__w/json/json/tests/src/unit-regression2.cpp(517): error: too many initializer values
              NonDefaultFromJsonStruct x(j);

These lines compile fine:

    auto x2 = j.get<NonDefaultFromJsonStruct>();
    auto x3 = j.operator NonDefaultFromJsonStruct();

Edit: First try #if condition didn't work.

[falbrechtskirchinger]

@nlohmann I'm still waiting for CI, so I don't know if anything else is needed. In any event, there are now a quite a few changes. You can either reference my branch here or I can open a PR, whichever you prefer.

[nlohmann]

@nlohmann I'm still waiting for CI, so I don't know if anything else is needed. In any event, there are now a quite a few changes. You can either reference my branch here or I can open a PR, whichever you prefer.

Please open a PR. You're already much deeper in this topic.

[falbrechtskirchinger]

Okay. Of course CI just failed so there's at least one more issue to solve...