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"
