Stability checker prevents return-position impl trait in the standard library

[scottmcm]

Previously hit here: #52896 (comment) (thanks, eddyb)

The way I hit this in a change I was trying:

   Compiling core v0.0.0 (file:///C:/src/rust/src/libcore)
←[0m←[1m←[38;5;9merror←[0m←[0m←[1m←[38;5;15m: This node does not have a stability attribute←[0m
←[0m   ←[0m←[0m←[1m←[38;5;14m--> ←[0m←[0mlibcore\num\f32.rs:604:35←[0m
←[0m    ←[0m←[0m←[1m←[38;5;14m|←[0m
←[0m←[1m←[38;5;14m604←[0m←[0m ←[0m←[0m←[1m←[38;5;14m| ←[0m←[0m    pub fn total_ordered(self) -> impl Ord {←[0m
←[0m    ←[0m←[0m←[1m←[38;5;14m| ←[0m←[0m                                  ←[0m←[0m←[1m←[38;5;9m^^^^^^^^←[0m

Instructions from oli-obk in #52896 (comment) :

Should be enough to add an arm to

rust/src/librustc/middle/stability.rs

Line 356 in a2af866

hir::ItemKind::Impl(.., None, _, _) | hir::ItemKind::ForeignMod(..) => {}

for ItemExistential(ExistTy { parent_fn_id: Some(_) }) which also skips the check_missing_stability call

[hellow554]

Your bash seems to use some fancy-dancy colors. Sadly github does not support control-sequences. Can you please edit your post and remove them? :)

[scottmcm]

@hellow554 Sadly that's what I literally get on windows these days, from x.py:

[ZerothLaw]

This looks like it is resolved - ran the exact same command @scottmcm used. Should this be closed?

[scottmcm]

@ZerothLaw Had you added an impl Trait to core when testing? I hit it with this extra change: scottmcm@af0afa9#diff-14f327fd5e3b91eb2e9af0690596d156R604

[ZerothLaw]

Okay, made the change to f32, and the suggested fix in stability.rs (with some changes) ran the command, getting this error:

error[E0460]: found possibly newer version of crate std which rand depends on
--> libcore../libcore/tests/lib.rs:46:1
|
46 | extern crate rand;
| ^^^^^^^^^^^^^^^^^^
|
= note: perhaps that crate needs to be recompiled?
= note: the following crate versions were found:
crate std: \?\C:\Users\z\source\repos\rust\build\x86_64-pc-windows-msvc\stage1-std\x86_64-pc-windows-msvc\release\deps\libstd-d0b1266efb775c6b.rlib
crate std: \?\C:\Users\z\source\repos\rust\build\x86_64-pc-windows-msvc\stage1\lib\rustlib\x86_64-pc-windows-msvc\lib\libstd-d0b1266efb775c6b.rlib
crate std: \?\C:\Users\z\source\repos\rust\build\x86_64-pc-windows-msvc\stage1-std\x86_64-pc-windows-msvc\release\deps\std-d0b1266efb775c6b.dll
crate std: \?\C:\Users\z\source\repos\rust\build\x86_64-pc-windows-msvc\stage1\lib\rustlib\x86_64-pc-windows-msvc\lib\std-d0b1266efb775c6b.dll
crate rand: \?\C:\Users\z\source\repos\rust\build\x86_64-pc-windows-msvc\stage1-std\x86_64-pc-windows-msvc\release\deps\librand-7403067dcfff573d.rlib

error: aborting due to previous error

For more information about this error, try rustc --explain E0460.
error: Could not compile core.

To learn more, run the command again with --verbose.

command did not execute successfully: "C:\Users\z\source\repos\rust\build\x86_64-pc-windows-msvc\stage0\bin\cargo.exe" "test" "--target" "x86_64-pc-windows-msvc" "-j" "4" "--release" "--features" "panic-unwind backtrace" "--manifest-path" "C:\Users\z\source\repos\rust\src/libstd/Cargo.toml" "-p" "core" "--" "total" "--quiet"
expected success, got: exit code: 101

failed to run: C:\Users\z\source\repos\rust\build\bootstrap\debug\bootstrap test --incremental --keep-stage 0 --stage 1 src\libcore --test-args total
Build completed unsuccessfully in 0:00:41

[ZerothLaw]

This seems to now be resolved on latest master branch.

[TheSirC]

Should this issue be closed @scottmcm ?

[workingjubilee]

There appear to be many instances of -> impl FnMut and others in core, this issue should be closed.

[Florian-Schoenherr]

found this randomly on codetribute lol
@scottmcm can you close this? 😄