is there any way to get error from speculative execution (`__traits( compiles, ...)`)? would be useful in tests; If not currently how hard would that be to implement? eg:
```
struct Status{bool ok; string msg;}
Status status = __traits(compilesReportError, {string b=10;})
assert(!status.ok);
assert(status.msg==`main.d(15) Error: cannot implicitly convert
expression 10 of type int to string`);
```
