Build errors (clang 11.0.0) on macOS 10.15.2

[zac-garby]

The library fails to build when running the unit tests or building it in part of another project.

I'm using clang (Apple clang version 11.0.0 (clang-1100.0.33.16)) on macOS Catalina 10.15.2.

I'm using a release version of json.

Here are some of the errors. I'll put the whole lot if you want.

/Users/zacgarby/code/c++/json/test/thirdparty/doctest/doctest.h:395:18: error: use of undeclared identifier
      'nullptr'
typedef decltype(nullptr) nullptr_t;
                 ^
/Users/zacgarby/code/c++/json/test/thirdparty/doctest/doctest.h:402:45: error: a space is required between
      consecutive right angle brackets (use '> >')
typedef basic_ostream<char, char_traits<char>> ostream;
                                            ^~
                                            > >
/Users/zacgarby/code/c++/json/test/thirdparty/doctest/doctest.h:993:6: error: expected expression
    [[noreturn]]
     ^

[nlohmann]

I cannot reproduce this on macOS 10.15.2 (19C57), Xcode Version 11.3 (11C29):

$ cmake .. -GXcode            
-- The CXX compiler identification is AppleClang 11.0.0.11000033
-- Check for working CXX compiler: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang++
-- Check for working CXX compiler: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Using the single-header code from /Users/niels/Documents/repositories/json/single_include/
-- Configuring done
-- Generating done
-- Build files have been written to: /Users/niels/Documents/repositories/json/build

$ cmake --build .

(a lot of output omitted)

Build all projects

** BUILD SUCCEEDED **

Could you please share the steps you took until you observed the issues?

[zac-garby]

For the unit tests, it turns out I wasn't building properly. But, the problem is still there for another project I'm trying to build which uses json as a dependency.

Unfortunately I can't show you the code, it's private and not my own repository.

I'm still getting the same errors, for example:

/Users/zacgarby/code/c++/melkor-ii/thirdparty/json.hpp:711:60: error: a space is required between consecutive
      right angle brackets (use '> >')
    typename It::reference, typename It::iterator_category >>
                                                           ^~
                                                           > >

Which makes me thing the problem is in our build setup, not the library (i.e. we're probably using the wrong language version or some pedantic error flags). So, I'll close this for now.

Thanks!

[AprilPolubiec]

I had the same issue on macOS 10.14.6, clang 11.0.0. Just had to add

set(CMAKE_CXX_STANDARD 11)
set(CMAKE_CXX_STANDARD_REQUIRED ON)

to my CMakeLists.txt.