next-solver: "expected generic lifetime parameter, found '_"

I tried to switch to next-solver, because of an ICE similar to this: #145482

This function fails to compile with:

error[E0792]: expected generic lifetime parameter, found `'_`
   --> /home/darksome/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/alloy-sol-macro-expander-1.3.0/src/expand/mod.rs:567:54
    |
530 | impl<'ast> ExpCtxt<'ast> {
    |      ---- this generic parameter must be used with a generic lifetime parameter
...
567 |         move |ty| self.custom_type(ty).is_value_type(self.custom_is_value_type())
    |

It works on stable and nightly without -Znext-solver

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rustc --version --verbose:

rustc 1.91.0-nightly (3672a55b7 2025-08-13)
binary: rustc
commit-hash: 3672a55b7cfd0a12e7097197b6242872473ffaa7
commit-date: 2025-08-13
host: x86_64-unknown-linux-gnu
release: 1.91.0-nightly
LLVM version: 21.1.0

pub fn f(_: &()) -> impl Fn() + '_ {
    || {
        let _ = f(&());
    }
}

godbolt

(this error has changed since #145244 landed yesterday: on nightly-2025-08-21 you get the OP, while on nightly-2025-08-22 it's an error: non-defining use of `impl Fn()` in the defining scope)

Rollup merge of rust-lang#149824 - ShoyuVanilla:issue-145748, r=Kivooeo

Unrolled build for #149824

Rollup merge of #149824 - ShoyuVanilla:issue-145748, r=Kivooeo

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next-solver: "expected generic lifetime parameter, found `'_`" #145748

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next-solver: "expected generic lifetime parameter, found '_" #145748

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lqd commented on Aug 22, 2025

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next-solver: "expected generic lifetime parameter, found `'_`" #145748