On 7/12/17 5:24 PM, Johan Engelen wrote:
On Wednesday, 12 July 2017 at 20:12:03 UTC, Steven Schveighoffer wrote:
...
Which means this may cause a bunch of nuisance errors.
It's a trade-off between nuisance in some cases (the Phobos ones can be
solved with val = abs(val), or with static if), and possibly catching
bugs in other cases.
We can compare this with negation of a bool and subtracting a bool:
```
bool b;
auto x = 1 - b; // allowed
auto y = -b; // not allowed
```
My only point is with Andrei's assertion that it "exposed two bugs in
Phobos".
In terms of the trade-off, it looks like this is just a straight bug
that should be fixed. If the behavior goes back to being like C, is it
still so bad that it needs an error?
My testing:
import std.stdio;
void main()
{
ubyte x = 5;
int y = -x;
writeln(y);
uint t = 0;
t += x;
writeln(t);
t += y;
writeln(t);
}
outputs:
251
5
256
In C:
#include <stdio.h>
int main()
{
unsigned char x = 5;
int y = -x;
printf("%d\n", y);
unsigned int t = 0;
t += x;
printf("%u\n", t);
t += y;
printf("%u\n", t);
return 0;
}
outputs:
-5
5
0
The C behavior seems fine to me.
-Steve
