Should (p - q) be disallowed in @safe code?

[Walter Bright]

On 1/2/2026 11:20 AM, jmh530 wrote:
> On Thursday, 1 January 2026 at 06:15:09 UTC, Walter Bright wrote:
>> [snip]
>> So this would be valid, as the two pointers are known to point to the same 
>> memory object.
>> [snip]
> 
> To what extent can D know when pointers are known to point to the same object?

Some can be done trivially, such as (&c - &d). More can be discovered with DFA 
(Data Flow Analysis), but not really that much. Just like not many cases of null 
dereference can be unambiguously discovered with DFA.