Compiler errors about const specifier in getter functions

[tonimueller]

A lot of getter functions are written like

const type getValue() const {return value;} 

where the compiler complains about the first const .
(https://stackoverflow.com/questions/21478342/c-const-in-getter
https://arne-mertz.de/2016/07/const-correctness/)
The correct way would be to write

type getValue() const {return value;} 

which does not alter the state of the object.