JSON for Modern C++ version 3.10.5

[nlohmann]

Release date: 2022-01-03
SHA-256: e832d339d9e0c042e7dff807754769d778cf5d6ae9730ce21eed56de99cb5e86 (json.hpp), b94997df68856753b72f0d7a3703b7d484d4745c567f3584ef97c96c25a5798e (include.zip)

Summary

The previous version 3.10.4 introduced support to convert std::filesystem objects to JSON and vice versa. Unfortunately, we made the assumption that any compiler supporting C++17 would also have proper filesystem support. This was a mistake. This release introduces preprocessor checks (and means to override them) to make sure that the conversion support is only compiled if the compiler is detected to support it.

All changes are backward-compatible.

💰 Note you can support this project via GitHub sponsors or PayPal.

🐛 Bug fixes

• Make sure C++17 filesystem conversions are only used if the compiler supports it. Furthermore, add defines JSON_HAS_FILESYSTEM and JSON_HAS_EXPERIMENTAL_FILESYSTEM which can be set to 0 to avoid using filesystem support altogether.std::filesystem. GCC 7.5.0 with --std=c++17: filesystem: No such file or directory #3090 Apple build failed with json/single_include/nlohmann/json.hpp:4384:57: 'path' is unavailable #3097 Add C++17 copies of the test binaries #3101 std::filesystem unavailable on macOS lower deployment targets #3156 #include <filesystem> doesn't work with gcc-7 when -std=c++17 is specified. #3203
• Fix a compilation error with Nvidia CUDA Compiler (NVCC). ordered_json::reset() compile error with nvcc #3013 Fix compilation error with NVCC #3234

Warnings

• Fix a warning for shadowed variables. Warning for shadowed variables #3188 Fix: Warning for shadowed variables (#3188) #3193
• Fix a warning on a pointless comparison. Add build step for NVCC and fix a warning #3227 Compiler warning with Intel compiler, same as #755 #2712 Compiler warnings with NVCC 11.2 #2676 some static analysis warning at line 11317 #1390 Compiling with icpc #755

⚡ Improvements

• Add a parameter to the update function to recursively merge objects with common keys. deep copy (or merge?) #3006 Add recursive update function #3069
• Extend std::hash and std::swap to work on any nlohmann::basic_json specializations rather than just nlohmann::json. Extend std specializations #3121

🔨 Further Changes

Tests and CI

• Update CI to use Clang 14, GCC 6, and Clang-Tidy 14. Update CI #3088
• Update cpplint. Update cpplint #3225
• Add build step for the Nvidia CUDA Compiler (NVCC). Add build step for NVCC and fix a warning #3227
• Remove Travis CI. Drop Travis CI #3087 Remove Travis CI #3233
• Compile and execute the test suite with C++17. Add C++17 copies of the test binaries #3101

Documentation

• The mkdocs-based documentation in doc/mkdocs has been totally overworked. It now has a unified structure, more examples, and contains all information from the previous Doxygen-based documentation. The single source of truth is now the documentation on https://json.nlohmann.me and in particular the API Documentation. Consolidate documentation #3071
• Removed Wandbox online examples. Consolidate documentation #3071
• Fix typos, links, and parameter names in the documentation. Fix typos in operator[] documentation #3102 Fix spelling #3125 fix typos in documentation #3140 Docs: Update skip_comments to ignore_comments #3145 Fix FAQ hyperlink typo in readme #3148
• Add more examples. Consolidate documentation #3071 Add examples for parsing from iterator pair #3100

🔥 Deprecated functions

Passing iterator pairs or pointer/length pairs to parsing functions (basic_json::parse, basic_json::accept, basic_json::sax_parse, basic_json::from_cbor, basic_json::from_msgpack, basic_json::from_ubjson, basic_json::from_bson) via initializer lists is deprecated. Instead, pass two iterators; for instance, call basic_json::from_cbor(ptr, ptr+len) instead of basic_json::from_cbor({ptr, len}).

The following functions have been deprecated in earlier versions and will be removed in the next major version (i.e., 4.0.0):

• Function iterator_wrapper are deprecated. Please use the member function items() instead.
• Functions friend std::istream& operator<<(basic_json&, std::istream&) and friend std::ostream& operator>>(const basic_json&, std::ostream&) are deprecated. Please use friend std::istream& operator>>(std::istream&, basic_json&) and friend operator<<(std::ostream&, const basic_json&) instead.

All deprecations are annotated with HEDLEY_DEPRECATED_FOR to report which function to use instead.

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This discussion was created from the release JSON for Modern C++ version 3.10.5.

[nmoreaud]

Could you release a version 3.10.6, which fixes parsing of json from iterator?
It is interesting to have a "stable" release.

(Re-add value_type detection to distinguish string types (was broken in releases 3.10.4, and 3.10.5). #3204, #3333, #3604, #3602, #3629)

[nlohmann]

I hope to have a new version out this month. I just fixed the CI and merged several ready MRs. Now I wait to have some more MRs rebased and conflict free.

[nmoreaud]

There is still a bug in version 3.10.5 which is shipped by multiple linux distributions

[nlohmann]

What do you propose?