dmd.root.array: Add sort method, wrapping qsort

[Geod24]

This makes it way more user-friendly to work with.
Unfortunately I cannot use it in the backend because it is using -betterC.
Will be useful when implementing GNU ABI Tags too.

[dlang-bot]

Thanks for your pull request, @Geod24!

Bugzilla references

Your PR doesn't reference any Bugzilla issue.

If your PR contains non-trivial changes, please reference a Bugzilla issue or create a manual changelog.

Testing this PR locally

If you don't have a local development environment setup, you can use Digger to test this PR:

dub run digger -- build "master + dmd#10896"

[thewilsonator]

ERROR: dmd/root/array.d(319): Error: function `core.stdc.stdlib.qsort` is not `nothrow`
dmd/root/array.d(314): Error: `nothrow` function `dmd.root.array.Array!(CaseStatement).Array.sort!(sort_compare).sort` may throw
dmd/statementsem.d(2721): Error: template instance `dmd.root.array.Array!(CaseStatement).Array.sort!(sort_compare)` error instantiating

[thewilsonator]

dmd\libmscoff.d(517): Error: template instance `sort!((ppe1, ppe2) => (**ppe1).opCmp(**ppe2))` cannot use local `__lambda3` as parameter to non-global template `sort(alias pred)()

[ibuclaw]

You just couldn't help yourself? :-)

[Geod24]

Uh dscanner complains about unused variable here...

[thewilsonator]

Hmm maybe use

static assert (!is(typeof((){Array!OtherStruct arr2; arr2.sort()}();)));
``

[Geod24]

Satisfied the style checker.

[ibuclaw]

It would appear that this line triggers a silent forward reference bug when compiling frontend modules separately. The early forced semantic of typeof(this.data[0]) (a ClassDeclaration when compiling mtype.d) messes up the vtable calculation, and the offset is wrong (when calling isBaseOf).

This happens in at least the dmd-cxx implementation, a suitable reduction and testing 2.066 will need to be done as well.

[ibuclaw]

Reduced, any compiler older than 2.085.1 runs the risk of producing a corrupted compiler if you are using incremental/one module at a time compilation strategy (2.085.0 is the last broken release).

FYI @kinke, or ping any other LDC devs so you don't repeat the time I spent looking at this issue. I've already committed a fix to dmd-cxx branch, see the cross-referenced merged PR.

[Geod24]

@ibuclaw :
Could you check if using a template constraint would work around the problem ? And if not, we can move the static assert in the body.

[ibuclaw]

I think template constraints would work just fine. The reduced test I added reports the correct offset at least...

[ibuclaw]

However, on further testing even if we fix the problematic static if, you cannot actually use this function anyway, as it relies on dual-context pointers, which is neither implemented in gdc nor ldc.

[Geod24]

I don't see where it does ? Let's move the discussion to #10930 though.