merge stable

[MartinNowak]

• Fix Issue 15909 - Duplicate case error reports characters as numbers
• Fix Issue 21282 - mixin of AliasSeq "cannot alias an expression" (Fix Issue 21282 - mixin of AliasSeq "cannot alias an expression" #11814)
• Fix Issue 21283 - [C++] Wrong mangling for ref of parameter pack
• bump VERSION to v2.094.1-beta.1

[dlang-bot]

Thanks for your pull request, @MartinNowak!

Bugzilla references

Auto-close	Bugzilla	Severity	Description
✓	15909	trivial	Duplicate case error reports characters as numbers
✓	21282	regression	mixin of AliasSeq "cannot alias an expression"
✓	21283	major	[C++] Wrong mangling for ref of parameter pack

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#11845"

[Geod24]

What's up with the Azure pipelines (Windows_LDC_MinGW win32-ldc) failure ? We're seeing it on other PRs as well, aren't we ?
CC @wilzbach @MoonlightSentinel

[thewilsonator]

We are.

[thewilsonator]

@BorisCarvajal there is a merge conflict in one of your PRs here. Please advise how it should be resolved.

[BorisCarvajal]

It seems there's a new errorRet() instead of t = Type.terror;, here:

    ds.error("cannot alias an expression `%s`", e.toChars());
    t = Type.terror;