shared - i need it to be useful

[Timon Gehr]

On 21.10.18 17:54, Nicholas Wilson wrote:
> 
>> As soon as that is done, you've got a data race with the other 
>> existing unshared aliases.
> 
> You're in @trusted code, that is the whole point. The onus is on the 
> programmer to make that correct, same with regular @safe/@trusted at system 
> code.

Not all of the parties that participate in the data race are in @trusted 
code. The point of @trusted is modularity: you manually check @trusted 
code according to some set of restrictions and then you are sure that 
there is no memory corruption.

Note that you are not allowed to look at any of the @safe code while 
checking your @trusted code. You will only see an opaque interface to 
the @safe code that you call and all you know is that all the @safe code 
type checks according to @safe rules. Note that there might be an 
arbitrary number of @safe functions and methods that you do not see.

Think about it this way: you first write all the @trusted and @system 
code, and some evil guy who does not like you comes in after you looks 
at your code and writes all the @safe code. If there is any memory 
corruption, it will be your fault and you will face harsh consequences. 
Now, design the @safe type checking rules. It won't be MP!

Note that there may well be a good way to get the good properties of MP 
without breaking the type system, but MP itself is not good because it 
breaks @safe.