From: Nick Desaulniers > Sent: 24 January 2020 17:20 ... > > > Good thing it's the variable being modified was not declared const; I > > > get spooked when I see -Wdiscarded-qualifiers because of Section > > > 6.7.3.6 of the ISO C11 draft spec: > > > > > > ``` > > > If an attempt is made to modify an object defined with a const-qualified > > > type through use of an lvalue with non-const-qualified type, > > > the behavior is undefined. Well some old systems had small integer constants at fixes addresses. So 'const int one = 1;' would be a reference to the global constant. An assignment like '*(int *)&one = 2;' would change the value of the system-wide 'one' constant'. Pretty much 'undefined'. But no excuse for the compiler just discarding the code. I suspect that the code to remove 'const' needs to 'launder' the value through a suitable integer type. David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)
