Question

public void Foo(double d){
    // when called below, d == 2^32-1 
    ...
}
public void Bar(){
    uint ui = 1;
    Foo( 0 - ui );
}

I would expect both 0 and ui to be promoted to signed longs here.

True, with the 0 literal it is knowable at compile time that a cast to uint is safe,

but I suppose this all just seems wrong. At least a warning should be issued.

Thanks!

Does the language spec cover a semi-ambiguous case like this?

Answer 1

It’s the int that is being cast to uint to perform substraction from 0 (which is implicitly interpreted by the compiler as uint). Note that int to uint is an implicit conversion hence no warning. There is nothing wrong with your code… except that uint is not CLS-compilant. You can read why here. More info on CLS-compilant code on MSDN