String copying fails when output from assert

[David Zhang]

On Tuesday, 21 November 2017 at 19:05:21 UTC, Jonathan M Davis 
wrote:
> Well, the assertion is going to throw an AssertError, which 
> takes a string for its message. It doesn't copy the contents of 
> the string. It's just taking a slice just like whenever you 
> pass a string to any other function. So, it refers to the same 
> memory as what's passed in. So, if what it's passed is a string 
> that refers to memory on the stack, then when it goes to print 
> the message, it's going to be garbage, because the stack was 
> unwound, and the static array is gone.
>
> Honestly, I'd argue that it's a bug that it allows you provide 
> a message as a char[] instead of immutable(char)[]. It seems 
> that the compiler is implicitly converting char[] to 
> immutable(char)[] in this case, which is very bad. It would 
> matter less if you were giving the assertion a char[] that 
> referred to memory on the heap, but it still shouldn't be 
> allowed.
>
> You really should be giving assertions a value that is an 
> actual string that lives on the heap when providing a message, 
> not a char[], and definitely not a char[] that's a slice of a 
> static array.
>
> - Jonathan M Davis

Right. So a literal would work, because it's in the .data 
segment, or inlined. Basically, only strings from the heap, or 
that are compiled into the code are valid for assert messages.

What kind of behavior would an assert from stdc have (id, 
betterC)?