if — CMake 3.23.0-rc3 Documentation
cmake.org › cmake › helpFalse if the constant is 0, OFF, NO, FALSE, N, IGNORE, NOTFOUND, the empty string, or ends in the suffix -NOTFOUND. Named boolean constants are case-insensitive. If the argument is not one of these specific constants, it is treated as a variable or string (see Variable Expansion further below) and one of the following two forms applies. if ...