Fix Issue 22717 - TypeInfo_Struct.equals swaps lhs and rhs parameters

[kinke]

Leading to a swapped rhs.opEquals(lhs) check if the opEquals method took its parameter by ref.

This depends on dlang/druntime#3718.

[dlang-bot]

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Bugzilla references

Auto-close	Bugzilla	Severity	Description
✓	22717	critical	object.TypeInfo_Struct.equals swaps lhs and rhs parameters

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#13593"

[kinke]

auto-tester failing is to be expected, as it doesn't support cloning same-named druntime/Phobos branches for PRs originating from the official repo. AFAIK, Azure and Cirrus already did support that; CircleCI newly does with an extra commit here. Buildkite needs something like dlang/ci#452; only LDC should fail.

[kinke]

I've changed the fix to only apply if the compiler is going to define __VERSION__ as 2099 - currently depending on whether there's a .git subdir in the DMD repo at build-time: if there is, git describe currently returns some v2.098.0-…, and __VERSION__ is going to be 2098; otherwise it's 2099 (from the fallback VERSION file).

[kinke]

Buildkite still needs to bump its LDC ref once it's prepared for the upcoming breaking change (ldc-developers/ldc#3910), then this PR is ready.

[kinke]

Ready now.

Note: all compilers with __VERSION__ >= 2099 are going to 'miscompile' all older DMD frontends, due to the unfortunate TemplateInstanceBox.opEquals() const-hack and according order-dependency.

[ibuclaw]

Well we never claimed that newer versions could build older - and, usually it's deprecations and import bugfixes that mean we can't go back more than a couple anyway without having to downgrade the host compiler. ;-)