I\'ve recently set up a MinGW + MSYS environment on my laptop to check how things are with Netbeans C/C++ support. Everything seems to work fine, however, during my testing
-Wall doesn't quite mean -Wall, -Wextra is already under fire for being a little overly pedantic.
As Christoph said, you are looking for -Wconversion. Its good to really dig in to what -Wall and -Wextra actually turn on, and just specify the -W flags you want in your make file, especially if treating warnings as errors.