JSON_HAS_RANGES

#define JSON_HAS_RANGES /* value */

This macro indicates whether the standard library has any support for ranges. Implies support for concepts. Possible values are 1 when supported or 0 when unsupported.

Default definition

The default value is detected based on the preprocessor macro __cpp_lib_ranges.

When the macro is not defined, the library will define it to its default value.

Known compiler/stdlib exclusions

Even when the feature-test macro __cpp_lib_ranges indicates ranges support is available, the library disables it on the following incomplete or broken toolchains:

  • GCC 11.1.0 — disabled (the shipped <ranges> header has a syntax error; issue #4440)
  • libstdc++ < 11 — disabled (incomplete C++20 ranges support; issue #4440)
  • Clang < 16 with libstdc++ — disabled (incomplete ranges support; issue #4440)
  • libc++ < 160000 — disabled (incomplete C++20 ranges support; issue #4440)
  • nvcc (CUDA) 12.0.x and 12.1.x — disabled (the enable_borrowed_range variable-template syntax triggers a parse error under these two toolkit versions; fixed in CUDA 12.2; issue #3907)

If JSON_HAS_RANGES is 0 despite __cpp_lib_ranges being defined, one of the exclusions above likely applies to your toolchain.

Examples

Example

The code below forces the library to enable support for ranges:

#define JSON_HAS_RANGES 1
#include <nlohmann/json.hpp>

...

Version history

  • Added in version 3.11.0.