Move trait prototype

[zannabianca1997]

Finishing the work started by @nia-e in #156018 :

Add a barebones implementation for Move (#149607), pending some diagnostics changes & tests.

TODO

• next solver currently errors when not enabling feature(move_trait)
• change printing of trait objects to not show Move
• change printing of opaque types to not show Move
• also make sure rustdoc handles move correctly
• valuable to look into why diesel regresses

r? lcnr

[rustbot]

Thanks for the pull request, and welcome! The Rust Project has assigned @lcnr (or someone else) to review your changes, you should hear from them (or someone else) within the next two weeks.

Please see the contribution instructions for more information.

[zannabianca1997]

A quick ./x.py test tests/ui locally to have a baseline

test result: FAILED. 9 passed; 206 failed; 21862 ignored; 0 measured; 0 filtered out; finished in 1.14s

[zannabianca1997]

test result: FAILED. 21801 passed; 32 failed; 244 ignored; 0 measured; 0 filtered out; finished in 168.70s

wow that were a lot of them. looks like the next batch is a bunch of fn that now has fn() + Move

[zannabianca1997]

looking at the errors, there is also a bunch of (dyn + 'static) printing.

Those are all checks going around the trait_alias feature, that created before empty trait object and now creates what are effectively dyn Move, that are being misprinted.

That sure raises a question - can we handle them now? ummm - putting this aside in favour of lower hanging fruits

[zannabianca1997]

@lcnr this last one (520bc2f)

it's better to break the ABI and accept all aymbol mangling containing Move or we have to decide a way to mangle ?Move? I know rust has no stable abi but to put it in all symbols seems a bit too much

[rust-log-analyzer]

The job x86_64-gnu-gcc-core-tests failed! Check out the build log: (web) (plain enhanced) (plain)

Click to see the possible cause of the failure (guessed by this bot)

   Compiling rand_xorshift v0.4.0
[RUSTC-TIMING] rand_core test:false 0.331
[RUSTC-TIMING] rand_xorshift test:false 0.194
[RUSTC-TIMING] rand test:false 0.646
error[E0080]: evaluation panicked: assertion failed: TypeId::of::<Garlic>().trait_info_of::<dyn Blah>().is_some()
    --> library/coretests/tests/mem/trait_info_of.rs:18:9
     |
  18 |         assert!(TypeId::of::<Garlic>().trait_info_of::<dyn Blah>().is_some());
     |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
     |         |
     |         evaluation of `mem::trait_info_of::test_implements_trait::{constant#0}` failed here
     |         in this macro invocation
     |
    ::: library/core/src/macros/mod.rs:1738:5
     |
1738 |     macro_rules! assert {
     |     ------------------- in this expansion of `assert!`

note: erroneous constant encountered
  --> library/coretests/tests/mem/trait_info_of.rs:17:5
   |
17 | /     const {
18 | |         assert!(TypeId::of::<Garlic>().trait_info_of::<dyn Blah>().is_some());
19 | |         assert!(TypeId::of::<Garlic>().trait_info_of::<dyn Blah + Send>().is_some());
20 | |         assert!(TypeId::of::<*const Box<Garlic>>().trait_info_of::<dyn Sync>().is_none());
21 | |         assert!(TypeId::of::<u8>().trait_info_of_trait_type_id(TypeId::of::<dyn Blah>()).is_none());
22 | |     }
   | |_____^

error[E0080]: evaluation panicked: called `Option::unwrap()` on a `None` value
  --> library/coretests/tests/mem/trait_info_of.rs:43:13
   |
43 | /             TypeId::of::<Garlic>()
44 | |             .trait_info_of_trait_type_id(TypeId::of::<dyn Blah>())
45 | |             .unwrap()
   | |_____________________^ evaluation of `mem::trait_info_of::test_dyn_creation::{constant#1}` failed here

note: erroneous constant encountered
  --> library/coretests/tests/mem/trait_info_of.rs:42:9
   |
42 | /         const {
43 | |             TypeId::of::<Garlic>()
44 | |             .trait_info_of_trait_type_id(TypeId::of::<dyn Blah>())
45 | |             .unwrap()
46 | |         }.get_vtable(),
   | |_________^

[RUSTC-TIMING] corebenches test:true 55.869
[RUSTC-TIMING] coretests test:true 62.663
rustc exited with signal: 6 (SIGABRT) (core dumped)
error: could not compile `coretests` (test "coretests") due to 2 previous errors

Caused by:
  process didn't exit successfully: `/checkout/obj/build/bootstrap/debug/rustc /checkout/obj/build/bootstrap/debug/rustc --crate-name coretests --edition=2024 library/coretests/tests/lib.rs --error-format=json --json=diagnostic-rendered-ansi,artifacts,future-incompat --emit=dep-info,link -C opt-level=3 -C embed-bitcode=no -C codegen-units=1 --warn=unexpected_cfgs --check-cfg 'cfg(target_has_reliable_f16)' --check-cfg 'cfg(target_has_reliable_f16_math)' --check-cfg 'cfg(target_has_reliable_f128)' --check-cfg 'cfg(target_has_reliable_f128_math)' -Cembed-bitcode=yes -Zunstable-options -Cforce-frame-pointers=non-leaf -C overflow-checks=on --test --check-cfg 'cfg(docsrs,test)' --check-cfg 'cfg(feature, values())' -C metadata=c627e5cfc765553f -C extra-filename=-b9e20869992ba8b8 --out-dir /checkout/obj/build/x86_64-unknown-linux-gnu/stage1-std/x86_64-unknown-linux-gnu/dist/build/coretests/b9e20869992ba8b8/out --target x86_64-unknown-linux-gnu -L dependency=/checkout/obj/build/x86_64-unknown-linux-gnu/stage1-std/x86_64-unknown-linux-gnu/dist/build/coretests/8f29888f1cdfcd7b/out -L dependency=/checkout/obj/build/x86_64-unknown-linux-gnu/stage1-std/x86_64-unknown-linux-gnu/dist/build/rand/9ef107f21862446d/out -L dependency=/checkout/obj/build/x86_64-unknown-linux-gnu/stage1-std/x86_64-unknown-linux-gnu/dist/build/rand_core/5f10a21fc93cb74a/out -L dependency=/checkout/obj/build/x86_64-unknown-linux-gnu/stage1-std/x86_64-unknown-linux-gnu/dist/build/rand_xorshift/7f8f09963ff821c9/out -L dependency=/checkout/obj/build/x86_64-unknown-linux-gnu/stage1-std/dist/build/coretests/b9e20869992ba8b8/out --extern coretests=/checkout/obj/build/x86_64-unknown-linux-gnu/stage1-std/x86_64-unknown-linux-gnu/dist/build/coretests/8f29888f1cdfcd7b/out/libcoretests-8f29888f1cdfcd7b.rlib --extern coretests=/checkout/obj/build/x86_64-unknown-linux-gnu/stage1-std/x86_64-unknown-linux-gnu/dist/build/coretests/8f29888f1cdfcd7b/out/libcoretests-8f29888f1cdfcd7b.rmeta --extern rand=/checkout/obj/build/x86_64-unknown-linux-gnu/stage1-std/x86_64-unknown-linux-gnu/dist/build/rand/9ef107f21862446d/out/librand-9ef107f21862446d.rlib --extern rand=/checkout/obj/build/x86_64-unknown-linux-gnu/stage1-std/x86_64-unknown-linux-gnu/dist/build/rand/9ef107f21862446d/out/librand-9ef107f21862446d.rmeta --extern rand_xorshift=/checkout/obj/build/x86_64-unknown-linux-gnu/stage1-std/x86_64-unknown-linux-gnu/dist/build/rand_xorshift/7f8f09963ff821c9/out/librand_xorshift-7f8f09963ff821c9.rlib --extern rand_xorshift=/checkout/obj/build/x86_64-unknown-linux-gnu/stage1-std/x86_64-unknown-linux-gnu/dist/build/rand_xorshift/7f8f09963ff821c9/out/librand_xorshift-7f8f09963ff821c9.rmeta -Zannotate-moves '--check-cfg=cfg(feature,values(any()))' -Zunstable-options -Zmacro-backtrace -Csplit-debuginfo=off -Cprefer-dynamic -Zinline-mir -Zinline-mir-preserve-debug -Zmir_strip_debuginfo=locals-in-tiny-functions -Clink-args=-Wl,-z,origin '-Clink-args=-Wl,-rpath,$ORIGIN/../lib' -Alinker-messages '-Zcrate-attr=doc(html_root_url="https://doc.rust-lang.org/nightly/")' -Cpanic=abort -Zpanic-abort-tests -Z binary-dep-depinfo` (exit status: 254)
Bootstrap failed while executing `--stage 1 test library/coretests`
Currently active steps:
test::Crate { build_compiler: Compiler { stage: 1, host: x86_64-unknown-linux-gnu, forced_compiler: false }, target: x86_64-unknown-linux-gnu, mode: Std, crates: ["coretests"] } at src/bootstrap/src/core/build_steps/test.rs:3518
Build completed unsuccessfully in 0:12:39
  local time: Sat Aug 22 18:26:50 UTC 2026

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