A debug class has started

WebFreak001 d.forum at webfreak.org
Mon Dec 13 12:06:53 UTC 2021

On Monday, 13 December 2021 at 11:09:18 UTC, drug wrote:
> On 13.12.2021 13:49, forkit wrote:
>> On Monday, 13 December 2021 at 09:49:05 UTC, forkit wrote:
>>> ....
>> char* w = cast(char*)str.toStringz; // this seems to be the 
>> solution
>> class has ended ;-)
> That's because `str` is initialized by a literal and you can 
> not change it by definition. When you call `toStringz` it 
> duplicates that literal (adding terminating zero at the end) 
> and the duplicate is mutable. I would recommend do not use 
> `toStringz` and just make duplicate of the literal - 
> https://run.dlang.io/is/vaosW0

important: toStringz _may_ do a copy with the current 
implementation but nothing in the docs states it actually does 
so. In fact there is commented out code where it [in the 
past](https://github.com/dlang/phobos/commit/bc412e7c3fa3f124d7f2785223318b45edd4b3e6#diff-b94766ba288f9b4b05ef1a4874e26724750e614afdcddaf4c2071d0f19d91595L217) just dereferenced the memory after the string and checked if it was 0.

You should really use `.dup` if you want to mutate your string. 
(You would need to duplicate anyway if you don't want an unsafe 

pro-tip for bugs like this: just slap `@safe:` at the start of 
every file, the compiler will tell you everything that is risky 
and the bug will 9/10 times just sort itself out by fixing what 
the compiler complains about. (just recently helped someone with 
this again, was a 3 minute fix for a big code-base where manually 
searching the issue would have taken much longer)

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