[dmd-internals] Most important patches before release of DMD2.047

[Walter Bright]

These are checked in now. Thanks!

Don Clugston wrote:
> There are a few more critical bugs which should be included in the
> next release if possible.
>
> (1) This wrong-code bug is subtle and disastrous. It affects even simple C code.
> 3398 Attributes inside a union screws data alignment
>
> (2) The new _error type should be a killer feature, but if the simple
> cases aren't dealt with, people will scream about it.
> Fixing these test cases will totally change the feel of the release.
> (This doesn't have a patch, since it's a pile of trivial, repetitive
> changes.  But I think the test case is quite useful).
> 4296 Reduce parasitic error messages
>
> (3) This one is not so critical, but quite embarrassing. It creates
> the impression that user-defined operators haven't been tested at all!
> 4231 Solitary opUnary Postincrement and Postdecrement user defined
> operators are broken.
>
> Less critical, but utterly trivial to fix are these missing line number bugs:
> 3662 Wrong compile error within struct constructor and C-style initializer
> 4270 Missing line number in 'can only catch class objects' error message
>
> Of course there are many other worthwhile patches, but I think these
> ones are the most urgent.
>
>