[C++] Invalid state management in generated code with precedence checks.

[szymonwieloch]

After enabling precedence checks (sbe.enable.precedence.checks=true) part of the generated code does not work because of mistakes in the internal state management.

For example this will not work:

MessageType msg(buffer, len);
std::cout << msg;

Will throw an exception indicating incorrect use of attributes. What seems to be the root cause of the problem is initialization of the m_codedState variable inside the constructor. Because it is not set explicitly by the constructor(inside the operator << body), it's value becomes:

CodecState m_codecState = CodecState::NOT_WRAPPED;

Which is obviously invalid as the constructor wraps the underlying buffer. It seems that the root cause is not setting the correct value of the m_codecState in the wrapping constructors.

[ZachBray]

Thank you for this and the other reports. I've raised PR #1033 to address this issue.