Windows/Visual Studio (through 2013) is unsupported

[smiley]

I was about to use this for a C++ project in Visual Studio 2013, but the header fails compilation entirely, thanks to a myriad of errors:

1>------ Build started: Project: jsondummy, Configuration: Debug Win32 ------
1>  main.cpp
1>d:\github\jsondummy\src\json.hpp(137): error C2061: syntax error : identifier 'iterator'
1>          d:\github\jsondummy\src\json.hpp(4893) : see reference to class template instantiation 'nlohmann::basic_json<ObjectType,ArrayType,StringType,BooleanType,NumberIntegerType,NumberFloatType,AllocatorType>' being compiled
1>d:\github\jsondummy\src\json.hpp(137): error C2238: unexpected token(s) preceding ';'
1>d:\github\jsondummy\src\json.hpp(143): error C2061: syntax error : identifier 'const_iterator'
1>d:\github\jsondummy\src\json.hpp(143): error C2238: unexpected token(s) preceding ';'
1>d:\github\jsondummy\src\json.hpp(149): error C2061: syntax error : identifier 'reverse_iterator'
1>d:\github\jsondummy\src\json.hpp(149): error C2238: unexpected token(s) preceding ';'
1>d:\github\jsondummy\src\json.hpp(155): error C2061: syntax error : identifier 'const_reverse_iterator'
1>d:\github\jsondummy\src\json.hpp(155): error C2238: unexpected token(s) preceding ';'
1>d:\github\jsondummy\src\json.hpp(382): error C3646: 'noexcept' : unknown override specifier
1>d:\github\jsondummy\src\json.hpp(385): error C3646: 'noexcept' : unknown override specifier
1>d:\github\jsondummy\src\json.hpp(402): warning C4346: 'std::is_constructible<ObjectType<StringType,nlohmann::basic_json<ObjectType,ArrayType,StringType,BooleanType,NumberIntegerType,NumberFloatType,AllocatorType>,>::key_type,V::key_type>::value' : dependent name is not a type
1>          prefix with 'typename' to indicate a type
1>d:\github\jsondummy\src\json.hpp(402): error C2146: syntax error : missing ',' before identifier 'and'
1>d:\github\jsondummy\src\json.hpp(402): error C2065: 'and' : undeclared identifier
1>d:\github\jsondummy\src\json.hpp(402): error C2143: syntax error : missing ',' before 'std::is_constructible<nlohmann::basic_json<ObjectType,ArrayType,StringType,BooleanType,NumberIntegerType,NumberFloatType,AllocatorType>,V::mapped_type>::value'
1>d:\github\jsondummy\src\json.hpp(402): error C2977: 'std::enable_if' : too many template arguments
1>          c:\program files (x86)\microsoft visual studio 12.0\vc\include\xtr1common(67) : see declaration of 'std::enable_if'
1>d:\github\jsondummy\src\json.hpp(403): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
1>d:\github\jsondummy\src\json.hpp(426): error C2065: 'not' : undeclared identifier
1>d:\github\jsondummy\src\json.hpp(426): warning C4346: 'nlohmann::basic_json<ObjectType,ArrayType,StringType,BooleanType,NumberIntegerType,NumberFloatType,AllocatorType>::iterator' : dependent name is not a type
1>          prefix with 'typename' to indicate a type
1>d:\github\jsondummy\src\json.hpp(426): error C2923: 'std::is_same' : 'nlohmann::basic_json<ObjectType,ArrayType,StringType,BooleanType,NumberIntegerType,NumberFloatType,AllocatorType>::iterator' is not a valid template type argument for parameter '_Ty2'
1>d:\github\jsondummy\src\json.hpp(426): error C2143: syntax error : missing ',' before 'std::integral_constant<bool,false>::value'
1>d:\github\jsondummy\src\json.hpp(427): error C2146: syntax error : missing ',' before identifier 'and'
1>d:\github\jsondummy\src\json.hpp(427): error C2065: 'and' : undeclared identifier
1>d:\github\jsondummy\src\json.hpp(427): error C2146: syntax error : missing ',' before identifier 'not'
1>d:\github\jsondummy\src\json.hpp(427): error C2065: 'not' : undeclared identifier
1>d:\github\jsondummy\src\json.hpp(427): warning C4346: 'nlohmann::basic_json<ObjectType,ArrayType,StringType,BooleanType,NumberIntegerType,NumberFloatType,AllocatorType>::const_iterator' : dependent name is not a type
1>          prefix with 'typename' to indicate a type
1>d:\github\jsondummy\src\json.hpp(427): error C2923: 'std::is_same' : 'nlohmann::basic_json<ObjectType,ArrayType,StringType,BooleanType,NumberIntegerType,NumberFloatType,AllocatorType>::const_iterator' is not a valid template type argument for parameter '_Ty2'
1>d:\github\jsondummy\src\json.hpp(427): error C2143: syntax error : missing ',' before 'std::integral_constant<bool,false>::value'
1>d:\github\jsondummy\src\json.hpp(428): error C2146: syntax error : missing ',' before identifier 'and'
1>d:\github\jsondummy\src\json.hpp(428): error C2065: 'and' : undeclared identifier
1>d:\github\jsondummy\src\json.hpp(428): error C2146: syntax error : missing ',' before identifier 'not'
1>d:\github\jsondummy\src\json.hpp(428): error C2065: 'not' : undeclared identifier
1>d:\github\jsondummy\src\json.hpp(428): warning C4346: 'nlohmann::basic_json<ObjectType,ArrayType,StringType,BooleanType,NumberIntegerType,NumberFloatType,AllocatorType>::reverse_iterator' : dependent name is not a type
1>          prefix with 'typename' to indicate a type
1>d:\github\jsondummy\src\json.hpp(428): error C2923: 'std::is_same' : 'nlohmann::basic_json<ObjectType,ArrayType,StringType,BooleanType,NumberIntegerType,NumberFloatType,AllocatorType>::reverse_iterator' is not a valid template type argument for parameter '_Ty2'
1>d:\github\jsondummy\src\json.hpp(428): error C2143: syntax error : missing ',' before 'std::integral_constant<bool,false>::value'
1>d:\github\jsondummy\src\json.hpp(429): error C2146: syntax error : missing ',' before identifier 'and'
1>d:\github\jsondummy\src\json.hpp(429): error C2065: 'and' : undeclared identifier
1>d:\github\jsondummy\src\json.hpp(429): error C2146: syntax error : missing ',' before identifier 'not'
1>d:\github\jsondummy\src\json.hpp(429): error C2065: 'not' : undeclared identifier
1>d:\github\jsondummy\src\json.hpp(429): warning C4346: 'nlohmann::basic_json<ObjectType,ArrayType,StringType,BooleanType,NumberIntegerType,NumberFloatType,AllocatorType>::const_reverse_iterator' : dependent name is not a type
1>          prefix with 'typename' to indicate a type
1>d:\github\jsondummy\src\json.hpp(429): error C2923: 'std::is_same' : 'nlohmann::basic_json<ObjectType,ArrayType,StringType,BooleanType,NumberIntegerType,NumberFloatType,AllocatorType>::const_reverse_iterator' is not a valid template type argument for parameter '_Ty2'
1>d:\github\jsondummy\src\json.hpp(429): error C2143: syntax error : missing ',' before 'std::integral_constant<bool,false>::value'
1>d:\github\jsondummy\src\json.hpp(430): error C2146: syntax error : missing ',' before identifier 'and'
1>d:\github\jsondummy\src\json.hpp(430): error C2065: 'and' : undeclared identifier
1>d:\github\jsondummy\src\json.hpp(430): error C2146: syntax error : missing ',' before identifier 'not'
1>d:\github\jsondummy\src\json.hpp(430): error C2065: 'not' : undeclared identifier
1>d:\github\jsondummy\src\json.hpp(430): error C2143: syntax error : missing ',' before 'std::is_same<V,ArrayType<nlohmann::basic_json<ObjectType,ArrayType,StringType,BooleanType,NumberIntegerType,NumberFloatType,AllocatorType>,>::iterator>::value'
1>d:\github\jsondummy\src\json.hpp(431): warning C4346: 'std::is_same<V,ArrayType<nlohmann::basic_json<ObjectType,ArrayType,StringType,BooleanType,NumberIntegerType,NumberFloatType,AllocatorType>,>::iterator>::value' : dependent name is not a type
1>          prefix with 'typename' to indicate a type
1>d:\github\jsondummy\src\json.hpp(431): error C2146: syntax error : missing ',' before identifier 'and'
1>d:\github\jsondummy\src\json.hpp(431): error C2065: 'and' : undeclared identifier
1>d:\github\jsondummy\src\json.hpp(431): error C2146: syntax error : missing ',' before identifier 'not'
1>d:\github\jsondummy\src\json.hpp(431): error C2065: 'not' : undeclared identifier
1>d:\github\jsondummy\src\json.hpp(431): error C2143: syntax error : missing ',' before 'std::is_same<V,ArrayType<nlohmann::basic_json<ObjectType,ArrayType,StringType,BooleanType,NumberIntegerType,NumberFloatType,AllocatorType>,>::const_iterator>::value'
1>d:\github\jsondummy\src\json.hpp(432): warning C4346: 'std::is_same<V,ArrayType<nlohmann::basic_json<ObjectType,ArrayType,StringType,BooleanType,NumberIntegerType,NumberFloatType,AllocatorType>,>::const_iterator>::value' : dependent name is not a type
1>          prefix with 'typename' to indicate a type
1>d:\github\jsondummy\src\json.hpp(432): error C2146: syntax error : missing ',' before identifier 'and'
1>d:\github\jsondummy\src\json.hpp(432): error C2065: 'and' : undeclared identifier
1>d:\github\jsondummy\src\json.hpp(432): error C2143: syntax error : missing ',' before 'std::is_constructible<nlohmann::basic_json<ObjectType,ArrayType,StringType,BooleanType,NumberIntegerType,NumberFloatType,AllocatorType>,V::value_type>::value'
1>d:\github\jsondummy\src\json.hpp(432): error C2977: 'std::enable_if' : too many template arguments
1>          c:\program files (x86)\microsoft visual studio 12.0\vc\include\xtr1common(67) : see declaration of 'std::enable_if'
1>d:\github\jsondummy\src\json.hpp(433): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
1>d:\github\jsondummy\src\json.hpp(434): error C2535: 'nlohmann::basic_json<ObjectType,ArrayType,StringType,BooleanType,NumberIntegerType,NumberFloatType,AllocatorType>::basic_json(const V &)' : member function already defined or declared
1>          d:\github\jsondummy\src\json.hpp(404) : see declaration of 'nlohmann::basic_json<ObjectType,ArrayType,StringType,BooleanType,NumberIntegerType,NumberFloatType,AllocatorType>::basic_json'
1>d:\github\jsondummy\src\json.hpp(485): warning C4346: 'std::is_constructible<NumberIntegerType,T>::value' : dependent name is not a type
1>          prefix with 'typename' to indicate a type
1>d:\github\jsondummy\src\json.hpp(485): error C2146: syntax error : missing ',' before identifier 'and'
1>d:\github\jsondummy\src\json.hpp(485): error C2065: 'and' : undeclared identifier
1>d:\github\jsondummy\src\json.hpp(485): error C2143: syntax error : missing ',' before 'std::numeric_limits<T>::is_integer'
1>d:\github\jsondummy\src\json.hpp(485): error C2977: 'std::enable_if' : too many template arguments
1>          c:\program files (x86)\microsoft visual studio 12.0\vc\include\xtr1common(67) : see declaration of 'std::enable_if'
1>d:\github\jsondummy\src\json.hpp(486): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
1>d:\github\jsondummy\src\json.hpp(487): warning C4346: 'std::numeric_limits<T>::is_integer' : dependent name is not a type
1>          prefix with 'typename' to indicate a type
1>d:\github\jsondummy\src\json.hpp(487): error C3646: 'noexcept' : unknown override specifier
1>d:\github\jsondummy\src\json.hpp(502): error C3646: 'noexcept' : unknown override specifier
1>d:\github\jsondummy\src\json.hpp(594): warning C4346: 'nlohmann::basic_json<ObjectType,ArrayType,StringType,BooleanType,NumberIntegerType,NumberFloatType,AllocatorType>::iterator' : dependent name is not a type
1>          prefix with 'typename' to indicate a type
1>d:\github\jsondummy\src\json.hpp(594): error C2923: 'std::is_same' : 'nlohmann::basic_json<ObjectType,ArrayType,StringType,BooleanType,NumberIntegerType,NumberFloatType,AllocatorType>::iterator' is not a valid template type argument for parameter '_Ty2'
1>d:\github\jsondummy\src\json.hpp(595): error C2146: syntax error : missing ',' before identifier 'or'
1>d:\github\jsondummy\src\json.hpp(595): error C2065: 'or' : undeclared identifier
1>d:\github\jsondummy\src\json.hpp(595): warning C4346: 'nlohmann::basic_json<ObjectType,ArrayType,StringType,BooleanType,NumberIntegerType,NumberFloatType,AllocatorType>::const_iterator' : dependent name is not a type
1>          prefix with 'typename' to indicate a type
1>d:\github\jsondummy\src\json.hpp(595): error C2923: 'std::is_same' : 'nlohmann::basic_json<ObjectType,ArrayType,StringType,BooleanType,NumberIntegerType,NumberFloatType,AllocatorType>::const_iterator' is not a valid template type argument for parameter '_Ty2'
1>d:\github\jsondummy\src\json.hpp(596): error C2143: syntax error : missing ',' before 'std::integral_constant<bool,false>::value'
1>d:\github\jsondummy\src\json.hpp(596): error C2977: 'std::enable_if' : too many template arguments
1>          c:\program files (x86)\microsoft visual studio 12.0\vc\include\xtr1common(67) : see declaration of 'std::enable_if'
1>d:\github\jsondummy\src\json.hpp(597): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
1>d:\github\jsondummy\src\json.hpp(748): error C3646: 'noexcept' : unknown override specifier
1>d:\github\jsondummy\src\json.hpp(761): error C3646: 'noexcept' : unknown override specifier
1>d:\github\jsondummy\src\json.hpp(762): warning C4346: 'std::is_nothrow_move_constructible<nlohmann::basic_json<ObjectType,ArrayType,StringType,BooleanType,NumberIntegerType,NumberFloatType,AllocatorType>::value_t>::value' : dependent name is not a type
1>          prefix with 'typename' to indicate a type
1>d:\github\jsondummy\src\json.hpp(762): error C2061: syntax error : identifier 'value'
1>d:\github\jsondummy\src\json.hpp(767): error C2091: function returns function
1>d:\github\jsondummy\src\json.hpp(779): error C3646: 'noexcept' : unknown override specifier
1>d:\github\jsondummy\src\json.hpp(838): error C3646: 'noexcept' : unknown override specifier
1>d:\github\jsondummy\src\json.hpp(851): error C3646: 'noexcept' : unknown override specifier
1>d:\github\jsondummy\src\json.hpp(857): error C3646: 'noexcept' : unknown override specifier
1>d:\github\jsondummy\src\json.hpp(863): error C3646: 'noexcept' : unknown override specifier
1>d:\github\jsondummy\src\json.hpp(869): error C3646: 'noexcept' : unknown override specifier
1>d:\github\jsondummy\src\json.hpp(875): error C3646: 'noexcept' : unknown override specifier
1>d:\github\jsondummy\src\json.hpp(881): error C3646: 'noexcept' : unknown override specifier
1>d:\github\jsondummy\src\json.hpp(887): error C3646: 'noexcept' : unknown override specifier
1>d:\github\jsondummy\src\json.hpp(893): error C3646: 'noexcept' : unknown override specifier
1>d:\github\jsondummy\src\json.hpp(906): warning C4346: 'std::is_convertible<ObjectType<StringType,nlohmann::basic_json<ObjectType,ArrayType,StringType,BooleanType,NumberIntegerType,NumberFloatType,AllocatorType>,>::key_type,T::key_type>::value' : dependent name is not a type
1>          prefix with 'typename' to indicate a type
1>d:\github\jsondummy\src\json.hpp(906): error C2146: syntax error : missing ',' before identifier 'and'
1>d:\github\jsondummy\src\json.hpp(906): error C2065: 'and' : undeclared identifier
1>d:\github\jsondummy\src\json.hpp(907): error C2143: syntax error : missing ',' before 'std::is_convertible<nlohmann::basic_json<ObjectType,ArrayType,StringType,BooleanType,NumberIntegerType,NumberFloatType,AllocatorType>,T::mapped_type>::value'
1>d:\github\jsondummy\src\json.hpp(907): error C2977: 'std::enable_if' : too many template arguments
1>          c:\program files (x86)\microsoft visual studio 12.0\vc\include\xtr1common(67) : see declaration of 'std::enable_if'
1>d:\github\jsondummy\src\json.hpp(907): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
1>d:\github\jsondummy\src\json.hpp(943): warning C4346: 'std::is_convertible<nlohmann::basic_json<ObjectType,ArrayType,StringType,BooleanType,NumberIntegerType,NumberFloatType,AllocatorType>,T::value_type>::value' : dependent name is not a type
1>          prefix with 'typename' to indicate a type
1>d:\github\jsondummy\src\json.hpp(943): error C2146: syntax error : missing ',' before identifier 'and'
1>d:\github\jsondummy\src\json.hpp(943): error C2065: 'and' : undeclared identifier
1>d:\github\jsondummy\src\json.hpp(943): error C2146: syntax error : missing ',' before identifier 'not'
1>d:\github\jsondummy\src\json.hpp(943): error C2065: 'not' : undeclared identifier
1>d:\github\jsondummy\src\json.hpp(943): error C2143: syntax error : missing ',' before 'std::is_same<nlohmann::basic_json<ObjectType,ArrayType,StringType,BooleanType,NumberIntegerType,NumberFloatType,AllocatorType>,T::value_type>::value'
1>d:\github\jsondummy\src\json.hpp(944): warning C4346: 'std::is_same<nlohmann::basic_json<ObjectType,ArrayType,StringType,BooleanType,NumberIntegerType,NumberFloatType,AllocatorType>,T::value_type>::value' : dependent name is not a type
1>          prefix with 'typename' to indicate a type
1>d:\github\jsondummy\src\json.hpp(944): error C2146: syntax error : missing ',' before identifier 'and'
1>d:\github\jsondummy\src\json.hpp(944): error C2065: 'and' : undeclared identifier
1>d:\github\jsondummy\src\json.hpp(944): error C2146: syntax error : missing ',' before identifier 'not'
1>d:\github\jsondummy\src\json.hpp(944): error C2065: 'not' : undeclared identifier
1>d:\github\jsondummy\src\json.hpp(944): error C2143: syntax error : missing ',' before 'std::is_arithmetic<T>::value'
1>d:\github\jsondummy\src\json.hpp(945): warning C4346: 'std::is_arithmetic<T>::value' : dependent name is not a type
1>          prefix with 'typename' to indicate a type
1>d:\github\jsondummy\src\json.hpp(945): error C2146: syntax error : missing ',' before identifier 'and'
1>d:\github\jsondummy\src\json.hpp(945): error C2065: 'and' : undeclared identifier
1>d:\github\jsondummy\src\json.hpp(945): error C2146: syntax error : missing ',' before identifier 'not'
1>d:\github\jsondummy\src\json.hpp(945): error C2065: 'not' : undeclared identifier
1>d:\github\jsondummy\src\json.hpp(945): error C2143: syntax error : missing ',' before 'std::is_convertible<std::string,T>::value'
1>d:\github\jsondummy\src\json.hpp(946): warning C4346: 'std::is_convertible<std::string,T>::value' : dependent name is not a type
1>          prefix with 'typename' to indicate a type
1>d:\github\jsondummy\src\json.hpp(946): error C2146: syntax error : missing ',' before identifier 'and'
1>d:\github\jsondummy\src\json.hpp(946): error C2065: 'and' : undeclared identifier
1>d:\github\jsondummy\src\json.hpp(946): error C2146: syntax error : missing ',' before identifier 'not'
1>d:\github\jsondummy\src\json.hpp(946): error C2065: 'not' : undeclared identifier
1>d:\github\jsondummy\src\json.hpp(947): error C2143: syntax error : missing ',' before 'nlohmann::has_mapped_type<T>::value'
1>d:\github\jsondummy\src\json.hpp(947): error C2977: 'std::enable_if' : too many template arguments
1>          c:\program files (x86)\microsoft visual studio 12.0\vc\include\xtr1common(67) : see declaration of 'std::enable_if'
1>d:\github\jsondummy\src\json.hpp(947): fatal error C1003: error count exceeds 100; stopping compilation
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========

This is on VS2013, and as far as I know it supports 90% of the standard (but not some of what you're using here, like noexcept).

Are you planning to support Visual Studio/Windows some time later on?

[nlohmann]

Hi @smiley,

I already had several requests about MSVC support, but even the 2015 version still lacks full C++11 support (see #50). As one of the goals of this project is to embrace "Modern C++", I do not plan to remove those features that are not supported by MSVC, I'm sorry :-)

I'm happy to link to forks that support MSVC though ;-)

All the best
Niels

[smiley]

I understand that and you shouldn't remove features to support another compiler, but some of the uses don't seem to be necessary. If you remove them, or use simplified forms of them, you can support VS2015+ without sacrificing the clarity & cleanliness of the code.

For example, line 137 (the first error) makes a type-aliasing declaration with its own class name:

/*!
@brief an iterator for a basic_json container
@ingroup container
*/
using iterator = basic_json::iterator;

And to a forward-declaration of the same name:

class iterator;

// ...

public:
    /// a random access iterator for the basic_json class
    class iterator : public std::iterator<std::random_access_iterator_tag, basic_json>

Is there a difference between these two? Because the second one works perfectly in VS: (and pretty much solves the one remaining problem in #50)

template<class T>
class foo {

class bar;

// Option 1:
using foobar = foo::bar;
// Option 2:
using foobar = bar;

public:
    class bar : public std::bar<A, foo>

noexcept is supported from VS2015, so I'll leave it there.

In line 386 you use and instead of &&. I see that it's a legitimate extension of C++ that isn't implemented in VC++, can you include the relevant header (iso646.h) on Windows? It's already available in Visual Studio's headers.

And that's just a bunch of changes that significantly improve matters. By doing the above I managed to reduce the number of errors on VS2013 to 33 (from 100+) and the only remaining quirks are language matters (referencing my own template class without a template argument specifier), user-defined string literals and referencing template classes in the type specifier without their type specifiers. (I had to remove noexcept as I had VS2013 locally installed, but I considered it supported)

Of them, the following are implemented in VS2015:

• User-defined literals
• noexcept
• Using a template class in a type-deductive form (without type arguments)
• Referencing the same class mid-declaration without its template arguments.

The last two might be implemented, I just can't find them at all (not even in "unimplemented" state) on the C++11/14/17 page at MSDN.

(Sorry if I'm wrong about some of this, I'm still learning my through parts of C++11 and, apparently, C++14/17)

[nlohmann]

I addressed the issue with the (admittedly superfluous) type alias and also included <ciso646> for the operators. If there are other issues that can be fixed so easily, please let me know.

[nlohmann]

I added a CMake file and enabled AppVeyor again. Though I chose MSVC 2015, the build is still failing (see https://ci.appveyor.com/project/nlohmann/json/build/370). As I am neither an expert in MSVC nor CMake, I am clueless how to proceed. Maybe you have an idea. (This also affects issue #50).

[smiley]

It looks like it still uses Visual Studio 2013 (VS12 is 2013, VS13 is 2015).

How is the project (.vcxproj) configured? A project can still be run with a newer version of Visual Studio but compiled with an older one.

[nlohmann]

It is all configured through the appveyor.yml and CMakelists.txt files. Do you have an idea what needs to be changed?

[nlohmann]

I made a change and tried again: https://ci.appveyor.com/project/nlohmann/json/build/372. It now seems to use Microsoft Visual Studio 14.0. However, there are still 100s of errors. :-(

[nlohmann]

Appveyor now runs with 19.0.22609.0 (Visual Studio 2015 CTP 6). There are still 100s of errors, but maybe some of them can be fixed easily. Help would be greatly appreciated!

[smiley]

I'll look into it tonight, maybe I could resolve more of these.

[suy]

In case it's helpful: Microsoft has released VS 2015RC with a table of the C++ features supported. I don't have that much experience with heavy template use, so I haven't given a try yet. I will probably do, but is unlikely I can help much. :)