C++
gcc HEAD 10.0.0 20191015 (experimental)
$ g++ prog.cc -Wall -Wextra -std=c++2a -pedantic-errors
prog.cc: In instantiation of 'int foo() [with T = bool]': prog.cc:15:22: required from here prog.cc:5:10: error: use of an operand of type 'bool' in 'operator++' is forbidden in C++17 5 | i++; | ~^~