The spec should warn against using copy constructors, not warn against using postblit constructors

[jmdavis]

Due to dlang/dmd#20970, any types with a copy constructor should not be used in a dynamic array or associative array, which realistically means that no one who isn't using -betterC should be using copy constructors.

However, the spec currently has a warning on postblit constructors, telling programmers to use copy constructors in new code instead. This might make sense if druntime supported copy constructors properly, but it doesn't. And until it does, IMHO, we really need to be warning programmers against using copy constructors and instead be telling them to use postblit constructors. Personally, I wasted a considerable amount of time because of this issue, because I did not realize that the support for copy constructors was not complete, and I'm one of the core contributors, and without the spec being correct with regards to the current state of things, plenty of other folks are going to make the same mistake.

[TurkeyMan]

I kinda feel like this is backwards; shouldn't the issue you describe be fixed instead of the spec being revised? That's a super-weird resolution to a bug. How do you arrive at the idea that revising the spec is the appropriate bug fix?

That said, I'm pretty horrified that copy constructors must have been added how many years ago, and you're saying they don't work? :/ .. This is just classic D! I mean, I did kinda know this because I've tried to use them and they did cause me problems, but I just assumed it was because I was doing something 'exotic'.

So, what do we do? It's almost impossible to do anything because everything is so fragile, nobody will ever do anything that addresses the overall brittle-ness, and then this hyper-conservative approach which leaves everything broken and never fix anything; it leads to people building around a broken ecosystem and depending on the quirks/bugs, and then people go "oh no, we can't fix anything because it'll break the code that was carefully adapted to the broken thing that we won't fix". Is this really where we want to be?

[rikkimax]

For AA's they'll be fixed once the implementation is converted to a template, since the compiler can kick in then. That is supposed to be done by @schveiguy this year hopefully.

I don't remember the status of dynamic array hooks being templated. @RazvanN7

[TurkeyMan]

Kinda feels like this is, like, maximum priority stuff? The language being in a state where you can't even successfully construct an object according to the spec is just, like, broken; in the most literal sense of the word.
It's like a "stop everything, all hands on deck until this is fixed" kinds thing... this situation shouldn't have persisted for a single day; how did this happen?

[dkorpel]

I think most D programmers are happily using plain structs / classes / base data types and don't care that much about postblits / copy constructors.

[TurkeyMan]

Mm. It's really un-fun to work without decent strings, dynamic arrays, maps, general collections, etc, though. It's been a gaping hole in the library forever.