3.6.0: warning: missing initializer for member 'std::array<char, 9ul>::_M_elems' [-Wmissing-field-initializers]

[ibc]

• What is the issue you have?

In file included from ../src/xxxxx.hpp:5:0,
../include/json.hpp: In instantiation of 'std::string nlohmann::detail::lexer<BasicJsonType>::get_token_string() const [with BasicJsonType = nlohmann::basic_json<>; std::string = std::basic_string<char>]':
../include/json.hpp:7107:17:   required from 'void nlohmann::detail::parser<BasicJsonType>::parse(bool, BasicJsonType&) [with BasicJsonType = nlohmann::basic_json<>]'
../include/json.hpp:18993:9:   required from 'static nlohmann::basic_json<ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer> nlohmann::basic_json<ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer>::parse(IteratorType, IteratorType, nlohmann::basic_json<ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer>::parser_callback_t, bool) [with IteratorType = const char*; typename std::enable_if<std::is_base_of<std::random_access_iterator_tag, typename std::iterator_traits<_InputIterator>::iterator_category>::value, int>::type <anonymous> = 0; ObjectType = std::map; ArrayType = std::vector; StringType = std::basic_string<char>; BooleanType = bool; NumberIntegerType = long int; NumberUnsignedType = long unsigned int; NumberFloatType = double; AllocatorType = std::allocator; JSONSerializer = nlohmann::adl_serializer; nlohmann::basic_json<ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer>::parser_callback_t = std::function<bool(int, nlohmann::detail::parser<nlohmann::basic_json<> >::parse_event_t, nlohmann::basic_json<>&)>]'
../include/json.hpp:20793:42:   required from here
../include/json.hpp:6861:40: warning: missing initializer for member 'std::array<char, 9ul>::_M_elems' [-Wmissing-field-initializers]
                 std::array<char, 9> cs{};
                                        ^

• Please describe the steps to reproduce the issue. Can you provide a small but working code example?

Just include single_include/nlohmann/json.hpp into a C++ project and compile it in Linux.

• Which compiler and operating system are you using? Is it a supported compiler?

Debian 8.11
gcc version 4.9.2 (Debian 4.9.2-10+deb8u1)

• Did you use a released version of the library or the version from the develop branch?

3.6.0 git tag

[ibc]

I think it may use {{}} as json.hpp already does in line 12811 and others:

/// a (hopefully) large enough character buffer
std::array<char, 64> number_buffer{{}};

This avoids the warning.

[nlohmann]

Strange: I compiled with GCC 9 and -Wmissing-field-initializers which did not trigger a warning. I'll check with GCC 4.9.

[nlohmann]

@ibc Could you please check if the issue is fixed with 7c55510?

[nlohmann]

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🔖 Release item

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Type

• ✨ New Feature
• 🐛 Bug Fix
• ⚡️ Improvement
• 🔨 Further Change
• 🔥 Deprecated function

Description

• Fixed a warning for missing field initializers. 3.6.0: warning: missing initializer for member 'std::array<char, 9ul>::_M_elems' [-Wmissing-field-initializers] #1527

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[ibc]

Hi, yes, by adding double {{}} the warning does not happen. I already tested it yesterday :)

[nlohmann]

Cool, thanks!