LLVM 16.0.6 issues warning for literal operators when Wdeprecated-literal-operator

[burcelee]

Description

This may not be a "bug", but it's a room for possible improvement. Basically as in the title. Issue appears of this commit to LLVM (https://reviews.llvm.org/rG5ce5e983f82c802e44faa8ed42d605d70c045ba9).

CPP ref also indicates the operator syntax used in json.hpp is deprecated:

https://en.cppreference.com/w/cpp/language/user_literal

Note: I already have a fix prepared in a fork, and can submit a PR. The change is entirely to whitespace.

Reproduction steps

I was able to reproduce the bug building a project with Emscripten (which has been upgraded to LLVM 16.0.6), but I imagine that's an unnessecary step.

Expected vs. actual results

Compile without warning.

Minimal code example

I have resolved the issue in my fork: https://github.com/burcelee/json. I'd be happy to open a PR, but was told to open an issue first by the contributors document.

Error messages

json.hpp:5176:35: error: identifier '_json' preceded by whitespace in a literal operator declaration is deprecated [-Werror,-Wdeprecated-literal-operator]
...

Compiler and operating system

LLVM 16.0.6, Ubuntu

Library version

latest

Validation

• The bug also occurs if the latest version from the develop branch is used.
• I can successfully compile and run the unit tests.

[dhentschel-truepic]

I just ran into this compile warning on my project this morning, and came here to see if had already been reported. Thank you @burcelee for being proactive and putting together a fix. I would love to see this integrated into a release ASAP.