Designated initializers are not valid in C++11

[guilhermeferreira]

In some test cases, there are some member initializations like this:

MQTTAsync_successData data = {
	.token = MESSAGE_ID,
};

This feature is called designated initializers. It is an addition to C99 but left out of C++11. According to The C++ Programming Language, 4th edition, section 44.3.3.2 (C Features Not Adopted by C++):

A few additions to C99 (compared with C89) were deliberately not adopted in C++:
[1] Variable-length arrays (VLAs); use vector or some form of dynamic array
[2] Designated initializers; use constructors

The C11 grammar has the designated initializers [ISO/IEC 9899:2011 N1570 Committee Draft - April 12, 2011]

6.7.9 Initialization

    initializer:
        assignment-expression
        { initializer-list }
        { initializer-list , }
    initializer-list:
        designation_opt initializer
        initializer-list , designationopt initializer
    designation:
        designator-list =
    designator-list:
        designator
        designator-list designator
    designator:
        [ constant-expression ]
        . identifier

However, the C++11 grammar does not have designated initializers [ISO/IEC 14882:2011 N3690 Committee Draft - May 15, 2013]

8.5 Initializers

    initializer:
        brace-or-equal-initializer
        ( expression-list )
    brace-or-equal-initializer:
        = initializer-clause
        braced-init-list
    initializer-clause:
        assignment-expression
        braced-init-list
    initializer-list:
        initializer-clause ...opt
        initializer-list , initializer-clause ...opt
    braced-init-list:
        { initializer-list ,opt }
        { }

[guilhermeferreira]

By the way, the error was caught by the AppVeyor during the unit testing compilation:

c:\projects\paho-mqtt-cpp\test\unit\token_test.h(146): error C2059: syntax error: '.'
c:\projects\paho-mqtt-cpp\test\unit\token_test.h(147): error C2143: syntax error: missing ';' before '}'
c:\projects\paho-mqtt-cpp\test\unit\token_test.h(149): error C2059: syntax error: 'switch'

[fpagliughi]

The unit tests will be totally rewritten in #169.