build fails in editor and mnttool with "error: reference to size is ambiguous"

[juanitotc]

Apparently:

The use of "using namespace std" and declaring a variable named "size"
leads to problems in C++17 mode and hence GCC 11. There is ambiguity
because C++17 has "std::size" in the standard library.

[clbr]

You can rename the var, or build with -std=gnu++11 or similar.

[juanitotc]

-std=gnu++11 works