Rebase onto current rust-lang/rust master

[futile]

Hi, I went ahead and did a rebase against rust's current master.

x test tidy and x check both pass.

Since the first two commits are no longer compatible with master (some new types that don't have Hash), but the last commit removes Hash again anyway, I marked those two commits as "does not compile". But the final state (with all three commits) compiles again (and passes tidy & check).

There are two new failures when running x test tests/ui, but also more tests in total, so that makes sense.

Failures from the PR CI: https://github.com/rust-lang/rust/actions/runs/9232104911/job/25402877228?pr=125356

Failures with this rebase:

$ x test tests/ui

[...]

failures:
    [ui] tests/ui/array-slice-vec/vec-macro-with-comma-only.rs
    [ui] tests/ui/const-generics/min_const_generics/macro-fail.rs
    [ui] tests/ui/editions/edition-keywords-2015-2015-parsing.rs
    [ui] tests/ui/editions/edition-keywords-2015-2018-parsing.rs
    [ui] tests/ui/editions/edition-keywords-2018-2015-parsing.rs
    [ui] tests/ui/editions/edition-keywords-2018-2018-parsing.rs
    [ui] tests/ui/empty/empty-comment.rs
    [ui] tests/ui/fail-simple.rs
    [ui] tests/ui/issues/issue-7970a.rs
    [ui] tests/ui/macros/assert-trailing-junk.rs#with-generic-asset
    [ui] tests/ui/macros/assert-trailing-junk.rs#without-generic-asset
    [ui] tests/ui/macros/best-failure.rs
    [ui] tests/ui/macros/expr_2021_inline_const.rs#edi2021
    [ui] tests/ui/macros/expr_2024_underscore_expr.rs#edi2021
    [ui] tests/ui/macros/expr_2021_inline_const.rs#edi2024
    [ui] tests/ui/macros/expr_2024_underscore_expr.rs#edi2024
    [ui] tests/ui/macros/issue-103529.rs
    [ui] tests/ui/macros/local-ambiguity-multiple-parsing-options.rs
    [ui] tests/ui/macros/macro-at-most-once-rep-2015.rs
    [ui] tests/ui/macros/macro-at-most-once-rep-2018.rs
    [ui] tests/ui/macros/macro-match-nonterminal.rs
    [ui] tests/ui/macros/macro-missing-fragment-deduplication.rs
    [ui] tests/ui/macros/macro-missing-fragment.rs#e2015
    [ui] tests/ui/macros/macro-missing-fragment.rs#e2024
    [ui] tests/ui/macros/macro-non-lifetime.rs
    [ui] tests/ui/macros/missing-comma.rs
    [ui] tests/ui/macros/nonterminal-matching.rs
    [ui] tests/ui/macros/recovery-allowed.rs
    [ui] tests/ui/macros/trace_faulty_macros.rs
    [ui] tests/ui/offset-of/offset-of-arg-count.rs
    [ui] tests/ui/offset-of/offset-of-tuple.rs
    [ui] tests/ui/or-patterns/or-patterns-syntactic-fail-2018.rs
    [ui] tests/ui/parser/macro/issue-33569.rs
    [ui] tests/ui/parser/macro/macro-doc-comments-2.rs
    [ui] tests/ui/parser/macro/macro-doc-comments-1.rs
    [ui] tests/ui/rfcs/rfc-2294-if-let-guard/feature-gate.rs
    [ui] tests/ui/rfcs/rfc-2497-if-let-chains/feature-gate.rs
    [ui] tests/ui/underscore-ident-matcher.rs

test result: FAILED. 16849 passed; 38 failed; 542 ignored; 0 measured; 0 filtered out; finished in 196.44s

Some tests failed in compiletest suite=ui mode=ui host=x86_64-unknown-linux-gnu target=x86_64-unknown-linux-gnu

Is this helpful? Can you see something obvious I missed? Thanks! :)