Fix ICE in label_fn_like for splatted args and add UI tests

[Ajay-singh1]

This PR builds on top of #153697 (teor's #[splat] implementation).

Bug Fix

While writing UI tests for the unhappy path of the overload-at-home example, I discovered an ICE when calling a splatted function with an argument combination that has no registered impl:

foo.method(42i32, 42i32); // no impl for (i32, i32)
// ICE: arg index 1 out of bounds for method with 1 inputs

The condition !tuple_arguments.is_splatted() in label_fn_like was inverted , the safe use_splat_fallback path ran for non-splatted functions, and the span_bug! fired for splatted ones. Fix is removing the !.

After the fix the compiler gives a clean error instead:

error[E0308]: mismatched types expected String, found i32

CC: @teor2345

[rustbot]

Some changes occurred in compiler/rustc_hir/src/attrs

cc @jdonszelmann, @JonathanBrouwer

Some changes occurred in compiler/rustc_attr_parsing

cc @jdonszelmann, @JonathanBrouwer

rust-analyzer is developed in its own repository. If possible, consider making this change to rust-lang/rust-analyzer instead.

cc @rust-lang/rust-analyzer

HIR ty lowering was modified

cc @fmease

Some changes occurred to the CTFE / Miri interpreter

cc @rust-lang/miri

The reflection data structures are tied exactly to the implementation
in the compiler. Make sure to also adjust rustc_const_eval/src/const_eval/type_info.rs

cc @oli-obk

Some changes occurred to the CTFE machinery

cc @RalfJung, @oli-obk, @lcnr

The Miri subtree was changed

cc @rust-lang/miri

This PR changes rustc_public

cc @oli-obk, @celinval, @ouz-a, @makai410

Some changes occurred in compiler/rustc_passes/src/check_attr.rs

cc @jdonszelmann, @JonathanBrouwer

The Cranelift subtree was changed

cc @bjorn3

[rustbot]

Failed to set assignee to teor2345: invalid assignee

Note: Only org members with at least the repository "read" role, users with write permissions, or people who have commented on the PR may be assigned.

[RalfJung]

I'd recommend opening such PRs as a draft until they are ready for review. That avoids pinging everyone. :)

[teor2345]

Looks good, just a few tweaks to improve the test coverage. Feel free to edit your existing commits and force-push, or add fixup commits.

(Normally we use fixup commits to make reviews easier when there are rebases, then squash when the PR is ready. But in this case it doesn't matter.)

View changes since this review

[teor2345]

This test looks good, but no need to repeat the file path at the top of the file. The comment describing the purpose of the test is enough.

(This comment applies to each test file.)

Suggested change

// tests/ui/splat/splat-generics-inside-tuple.rs

[teor2345]

Please add part of the error text here (and below), so we know if we accidentally change the error type

Suggested change

	//~^ ERROR
	//~^ ERROR method `method` has an incompatible type for trait

[teor2345]

r? teor2345