Is this a bug?
Is it possible to store different generic types? via Digitalmars-d
digitalmars-d at puremagic.com
Sat Dec 10 00:16:48 PST 2016
On Saturday, 10 December 2016 at 08:09:00 UTC, Is it possible to
store different generic types? wrote:
> I'm pretty sure the following code should work, but it doesn't.
>
> ```
> bool intersect(ptrdiff_t targetX, ptrdiff_t targetY, size_t
> targetWidth, size_t targetHeight, ptrdiff_t x, ptrdiff_t y,
> size_t width, size_t height)
> {
> return targetX < x + width &&
> x < targetX + targetWidth &&
> targetY < y + height &&
> y < targetY + targetHeight;
> }
>
> void main() {
> import std.stdio;
> writeln(intersect(0,0,800,600, 0,150,148,148));
> writeln(intersect(0,0,800,600, -10,150,148,148));
> }
> ```
>
> It outputs:
> ```
> true
> false
> ```
>
> On the contrary if you write the same piece of code in other
> languages ex. C#
>
> (Ran it through Linqpad)
> ```
> bool intersect(int targetX, int targetY, uint targetWidth, uint
> targetHeight, int x, int y, uint width, uint height)
> {
> return targetX < x + width &&
> x < targetX + targetWidth &&
> targetY < y + height &&
> y < targetY + targetHeight;
> }
>
> void Main() {
> intersect(0,0,800,600, 0,150,148,148).Dump();
> intersect(0,0,800,600, -10,150,148,148).Dump();
> }
> ```
>
> Then it outputs:
> ```
> true
> true
> ```
>
> Is it a bug or is it intended behavior?
Okay the issue seem to be that D casts the left-hand argument to
the same type as the right-hand argument.
So when ex. doing "targetX < x + width" then it actually does
"targetX < cast(width_type)x + width"
Where as I'd believe the behavior should have been "targetX < x +
cast(x_type)width"
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