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Niels Lohmann
ecff144b3a
PR #5248 added a 5th JSON_HAS_RANGES exclusion branch to macro_scope.hpp (nvcc CUDA 12.0.x/12.1.x, fixed in 12.2, issue #3907) shortly after #5252 added the "Known compiler/stdlib exclusions" list to json_has_ranges.md, so the new branch was missing from the just-added doc section. Bring the list back to parity with the code (5 exclusion branches, 5 documented). Signed-off-by: Niels Lohmann <mail@nlohmann.me>
1.8 KiB
1.8 KiB
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 __cpp_lib_ranges.
When the macro is not defined, the library will define it to its default value.
!!! info "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](https://github.com/nlohmann/json/issues/4440))
- **libstdc++ < 11** — disabled (incomplete C++20 ranges support; [issue #4440](https://github.com/nlohmann/json/issues/4440))
- **Clang < 16 with libstdc++** — disabled (incomplete ranges support; [issue #4440](https://github.com/nlohmann/json/issues/4440))
- **libc++ < 160000** — disabled (incomplete C++20 ranges support; [issue #4440](https://github.com/nlohmann/json/issues/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](https://github.com/nlohmann/json/issues/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:
```cpp
#define JSON_HAS_RANGES 1
#include <nlohmann/json.hpp>
...
```
Version history
- Added in version 3.11.0.