Stop generating _d_eh_personality with -betterC

[kubo39]

Closes #3479

[kubo39]

Hmm, it seems ldc should not generate landing pads when --checkaction=halt was given.
Edit: Ahh, checkaction should affect assert/boundscheck/final-switch only..

[kinke]

Thx for tackling this. - The issue should be the same as reported in the forum a short while ago, and which I've redirected to https://issues.dlang.org/show_bug.cgi?id=20897, because I think the frontend should take care of not emitting any TryFinallyStatements in betterC mode (everything that can be handled there is to be preferred, so that we don't have these ugly special cases in each compiler backend). It generates this AST for the testcase:

int a = 5;
try
{
    create(0u, 1u, "2");
    return 0;
}
finally
    a = 6;

and expects each compiler to further lower this to:

int a = 5;
{
    create(0u, 1u, "2");
    return 0;
}
{
    a = 6;
}

which it trivially can and should do itself. Edit: And which it already does for manual try/finally written by the user.

[kinke]

Ouch, I've completely overlooked that return 0...

[kubo39]

Thanks for having a look, I agree with that so closing this.