Release date: 2018-10-05

SHA-256: f1327bb60c58757a3dd2b0c9c45d49503d571337681d950ec621f8374bcc14d4 (json.hpp), 9588d63557333aaa485e92221ec38014a85a6134e7486fe3441e0541a5a89576 (include.zip)

This release adds support for **GCC 4.8**. Furthermore, it adds a function [**`get_to`**](http://nlohmann.github.io/json/classnlohmann_1_1basic__json_a8a3db7d78f74232d3a6fb8f1abf69709.html#a8a3db7d78f74232d3a6fb8f1abf69709) to write a JSON value to a passed reference. Another topic of this release was the **CMake support** which has been overworked and documented.

Besides, a lot of bugs have been fixed and slight improvements have been made. All changes are backward-compatible.

- The library can now also built with **GCC 4.8**. Though this compiler does not fully support C++11, it can successfully compile and run the test suite. Note that bug [57824](https://gcc.gnu.org/bugzilla/show_bug.cgi?id=57824) in GCC 4.8 still forbids to use multiline raw strings in arguments to macros. #1257
- Added new function [**`get_to`**](http://nlohmann.github.io/json/classnlohmann_1_1basic__json_a8a3db7d78f74232d3a6fb8f1abf69709.html#a8a3db7d78f74232d3a6fb8f1abf69709) to write a JSON value to a passed reference. The destination type is automatically derived which allows more succinct code compared to the `get` function. #1227 #1231

- Fixed a bug in the CMake file that made `target_link_libraries` to not properly include `nlohmann_json`. #1243 #1245 #1260
- Fixed a warning in MSVC 2017 complaining about a constexpr if. #1204 #1268 #1272
- Fixed a bug that prevented compilation with ICPC. #755 #1222
- Improved the SFINAE correctness to fix a bug in the conversion operator. #1237 #1238
- Fixed a `-Wctor-dtor-privacy` warning. #1224
- Fixed a warning on a lambda in unevaluated context. #1225 #1230
- Fixed a bug introduced in version 3.2.0 where defining `JSON_CATCH_USER` led to duplicate macro definition of `JSON_INTERNAL_CATCH`. #1213 #1214
- Fixed a bug that prevented compilation with Clang 3.4.2 in RHEL 7. #1179 #1249

- Added [documentation on CMake integration](https://github.com/nlohmann/json#cmake) of the library. #1270
- Changed the CMake file to use `find_package(nlohmann_json)` without installing the library. #1202
- Improved error messages in case `operator[]` is used with the wrong combination (json.exception.type_error.305) of JSON container type and argument type. Example: "cannot use operator[] with a string argument". #1220 #1221
- Added a license and version information to the Meson build file. #1252
- Removed static assertions to indicated missing `to_json` or `from_json` functions as such assertions do not play well with SFINAE. These assertions also led to problems with GMock. #960 #1212 #1228
- The test suite now does not wait forever if run in a wrong directory and input files are not found. #1262
- The test suite does not show deprecation warnings for deprecated functions which frequently led to confusion. #1271

- GCC 4.8 and Xcode 10 were added to the [continuous integration suite](https://travis-ci.org/nlohmann/json) at Travis.
- Added [lgtm](https://lgtm.com/projects/g/nlohmann/json/context:cpp) checks to pull requests.
- Added tests for CMake integration. #1260

This release does not deprecate any functions. As an overview, 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`](http://nlohmann.github.io/json/classnlohmann_1_1basic__json_af1592a06bc63811886ade4f9d965045e.html#af1592a06bc63811886ade4f9d965045e) are deprecated. Please use the member function [`items()`](http://nlohmann.github.io/json/classnlohmann_1_1basic__json_afe3e137ace692efa08590d8df40f58dd.html#afe3e137ace692efa08590d8df40f58dd) instead.
- Functions [`friend std::istream& operator<<(basic_json&, std::istream&)`](http://nlohmann.github.io/json/classnlohmann_1_1basic__json_ab7285a92514fcdbe6de505ebaba92ea3.html#ab7285a92514fcdbe6de505ebaba92ea3) and [`friend std::ostream& operator>>(const basic_json&, std::ostream&)`](http://nlohmann.github.io/json/classnlohmann_1_1basic__json_a9e06deabe69262c3ffc5533d32856983.html#a9e06deabe69262c3ffc5533d32856983) are deprecated. Please use [`friend std::istream&  operator>>(std::istream&, basic_json&)`](http://nlohmann.github.io/json/classnlohmann_1_1basic__json_aaf363408931d76472ded14017e59c9e8.html#aaf363408931d76472ded14017e59c9e8) and [`friend operator<<(std::ostream&, const basic_json&)`](http://nlohmann.github.io/json/classnlohmann_1_1basic__json_a5e34c5435e557d0bf666bd7311211405.html#a5e34c5435e557d0bf666bd7311211405) instead.