dmain uses Throwable.toString to print an exception/error

[Dav1dde]

This allows to actually override Throwable.toString and have a custom exception body, it also removes the code duplictation of printing the stacktrace.

[alexrp]

This change may seem harmless, but there's a gotcha: Throwable.toString() uses the GC due to the way it concatenates strings, while the code here doesn't. I'm not sure if this is a problem in practice (but I think it can be if an OutOfMemoryError has been thrown).

[Dav1dde]

Like here?

Maybe branch of, if it's an OutOfMemoryError or any kind of Error and use the old way of printing the stacktrace? (There is this cast to Error anyways).

Pseudo:

auto e = cast(Error)t;
if(e is null) {
    // it's an exception
    console(t.toString());
} else {
   // do it the old way
}

[alexrp]

@dawgfoto I think you know these mechanics of the runtime better than I do, can you weigh in? What's the best way we could do this such that all non-OOME errors use Throwable.toString()?

[complexmath]

Switching to toString is fine as far as OutOfMemoryError is concerned--OOME overrides toString anyway. However, the reason for the current exception display approach is consistency. I'd originally used toString, and people complained that if they overrode toString they lost the formatting provided to built-in exceptions. The proper approach may be to change printMsgLine to print t.toString instead of t.msg and leave the rest in place.

[alexrp]

@Dav1dde ping

[alexrp]

Closing this. @Dav1dde feel free to open a new pull request with the aforementioned changes.