[WIP] changes for next release 3.11.1

[nlohmann]

This thread collects all changes made since the 3.11.0 (#3639) release.

Summary

Version 3.11.0 moved the user-defined string literals (UDL) into namespace nlohmann::literals::json_literals (see documentation). Unfortunately, this namespace was not imported to the global namespace by default which broke code. This release fixes this bug.

All changes are backward-compatible. See release notes of version 3.11.0 for more information on other features.

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🐛 Bug fixes

• Set default value of JSON_USE_GLOBAL_UDLS and the CMake options JSON_GlobalUDLs to 1 to import the user-defined string literals from the nlohmann::literals::json_literals namespace into the global namespace by default.
  • _json operator""()  #3644
  • Regression: no matching literal operator for call to 'operator""_json' #3645
  • Fix global UDLs #3646

[falbrechtskirchinger]

Set default value of JSON_GLOBAL_UDLS to 1 to import the nlohmann::literals::json_literals namespace to the global namespace by default.

The macro is named JSON_USE_GLOBAL_UDLS and the CMake options JSON_GlobalUDLs (following precedent).

Technically, it'd be more accurate to say: ... to import the user-defined string literals from the nlohmann::literals::json_literals namespace into the global namespace ...
Not too important of a distinction for users, but if we ever add another literal, it has to be added explicitly.