Compiler could elide many more postblit constructor calls
TommiT
tommitissari at hotmail.com
Sat Jun 29 10:57:32 PDT 2013
On Saturday, 29 June 2013 at 13:47:36 UTC, TommiT wrote:
> [..]
>
> Example:
>
> ----
> struct S
> {
> int[] values;
>
> this(this)
> {
> values = values.dup;
> }
> }
>
> void foo(const S) { }
>
> void main()
> {
> const S s;
> foo(s); // No need to call postblit
> }
One important related detail:
If the compiler decides to elide the postblit of S on the call to
foo(s), then the destructor of S (if S happened to have one)
should not be called when the call to foo exits and the argument
passed to foo goes out of scope. The logic behind this is that
when we omit the postblit on the argument that's passed by value,
it is as-if we had passed the argument by const reference (except
that the argument is considered local to foo, i.e. not returnable
by reference and what not).
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