On 2013-05-04 18:33:10 +0000, Walter Bright <newshou...@digitalmars.com> said:
Runtime Detection
There are still a few cases that the compiler cannot statically detect.
For these a runtime check is inserted, which compares the returned ref
pointer to see if it lies within the stack frame of the exiting
function, and if it does, halts the program. The cost will be a couple
of CMP instructions and an LEA. These checks would be omitted if the
-noboundscheck compiler switch was provided.
I just want to note that this has the effect of making any kind of heap
allocation not done by the GC unsafe. For instance, if you have a
container struct that allocates using malloc/realloc and that container
gives access to its elements by reference then you're screwed (it can't
be detected).
The obvious answer is to not make @trusted the function returning a
reference or a slice to malloced memory. But I remember Andrei wanting
to make standard containers of this sort at one point, so I think it's
important to note this limitation.
--
Michel Fortin
michel.for...@michelf.ca
http://michelf.ca/
