Providing implicit conversion of

[Siarhei Siamashka]

On Monday, 22 January 2024 at 01:14:06 UTC, Steven Schveighoffer 
wrote:
> On Sunday, 21 January 2024 at 16:05:40 UTC, Gavin Gray wrote:
>> The following code:
>>
>>   ulong charlie = 11;
>>   long johnstone = std.algorithm.comparison.max(0, -charlie);
>>   writeln(format!"johnstone %s"(johnstone));
>>
>> Results in (without any warning(s)):
>> johnstone -11
>>
>> However you choose to look at it, this means -11 > 0 
>> (regardless of all arguments concerning implicit conversions, 
>> 1's and 2's complements, being efficient, etc).
>>
>> The language should not allow unary unsigned anything.
>
> This is unlikely to get fixed, just due to the nature of D's 
> philosophy when it comes to C compatibility.

There's a hope that OpenD may try to improve the current 
situation. A related discussion can be found here: 
https://github.com/orgs/opendlang/discussions/4

> It would also break a lot of existing code.

How did you estimate that it's *a lot* of existing code? As an 
experiment, I tried to patch Druntime and Phobos to avoid signed 
overflows roughly a year ago: 
https://github.com/ssvb/gcc/commits/gdc-ftrapv-phobos-20220209/

And there were not too many places in the code that actually 
needed any fixes. Additionally taking care of unsigned overflows 
would surely require more changes, but I doubt that they are 
going to be big. In most cases encountering an arithmetic 
overflow is unexpected and undesired, it's typically the symptom 
of a bug in the code. Some clever bit-tricks relying on two's 
complement wrap-around exist, but they are: 1) not very common 2) 
can be easily debugged if arithmetic overflows are trapped at 
runtime 3) can be easily patched up. The two's complement 
wraparound behavior mandated by the D language spec is a 
non-technical political decision, intended to make life easier 
for the DMD compiler developers, but ignoring the needs of the 
users.