Reserved identifiers
INTERNATIONAL STANDARD ISO/IEC 14882:2020(E) Programming languages — C++ Sixth edition 2020-12-ISO (2020)
5.10 Identifiers [lex.name]
3 In addition, some identifiers are reserved for use by C++ implementations and shall not be used otherwise; no diagnostic is required.
3.1 Each identifier that contains a double underscore __ or begins with an underscore followed by an uppercase letter is reserved to the implementation for any use.
3.2 Each identifier that begins with an underscore is reserved to the implementation for use as a name in the global namespace.
Recommendation: rename variables containing at least one underscore at the beginning of the name.
For example, in classes: field_ or m_field.
Thanks, I should do it.
It should be fixed with the last few commits.