test ABI compatibility for some unsized types as well

[RalfJung]

and test for what DispatchFromDyn needs.

Also I ran this on a whole bunch of targets via Miri and added enough cfg to make it all work, as documentation for what does and doesn't currently work. (Most of those targets do not have their tests run on CI anyway.)

Here's the shell rune I used for that:

for TARGET in x86_64-unknown-linux-gnu x86_64-pc-windows-gnu aarch64-unknown-linux-gnu s390x-unknown-linux-gnu mips64-unknown-linux-gnuabi64 sparc64-unknown-linux-gnu  powerpc64-unknown-linux-gnu powerpc64le-unknown-linux-gnu riscv64gc-unknown-linux-gnu loongarch64-unknown-linux-gnu wasm32-unknown-unknown; do
   BOOTSTRAP_SKIP_TARGET_SANITY=1 ./x.py run miri --stage 0 --args tests/ui/abi/compatibility.rs --target $TARGET;
done

[rustbot]

r? @petrochenkov

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[petrochenkov]

@bors r+

[bors]

📌 Commit 6f2c051 has been approved by petrochenkov

It is now in the queue for this repository.

[bors]

⌛ Testing commit 6f2c051 with merge deb708a...

[bors]

☀️ Test successful - checks-actions
Approved by: petrochenkov
Pushing deb708a to master...

[rust-timer]

Finished benchmarking commit (deb708a): comparison URL.

Overall result: no relevant changes - no action needed

@rustbot label: -perf-regression

Instruction count

This benchmark run did not return any relevant results for this metric.

Max RSS (memory usage)

Results

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	3.1%	[3.1%, 3.1%]	1
Regressions ❌ (secondary)	2.6%	[1.2%, 4.0%]	2
Improvements ✅ (primary)	-2.8%	[-2.8%, -2.8%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.2%	[-2.8%, 3.1%]	2

Cycles

This benchmark run did not return any relevant results for this metric.

Binary size

This benchmark run did not return any relevant results for this metric.

Bootstrap: 630.656s -> 631.075s (0.07%)
Artifact size: 317.84 MiB -> 317.84 MiB (-0.00%)