DIP 1015--Deprecation of Implicit Conversion of Int. & Char. Literals to bool--Formal Assement

[Neia Neutuladh]

On Mon, 12 Nov 2018 14:07:39 -0800, Walter Bright wrote:
>      <implicit conversion> <exact>               => <implicit
>      conversion>
>      <implicit conversion> <implicit conversion> => <implicit
>      conversion>

One confusion is from value range propagation / constant folding reaching 
past the static type information to yield a different result from what 
static typing alone would suggest. My intuition was that the compiler 
should prefer the declared type of the symbol when it's got a symbol with 
a declared type.

Like, A implicitly converts to int, and int doesn't implicitly convert to 
short, so an expression of type A shouldn't implicitly convert to short. 
And this is *generally* true, but when the compiler can use constant 
folding to get a literal value out of the expression, it does things I 
don't expect.

And this doesn't happen with structs with alias this, but I can't tell if 
that's an oversight or not, and there's no doubt some nuanced explanation 
of how things work, and it probably solves some edge cases to have it work 
differently...