Do not ICE on unmet trait alias bounds

[eggyal]

Obligations derived from trait alias predicates are not from any impl and therefore should be DerivedObligation rather than ImplDerivedObligation.

Fixes #108072

r? compiler

[eggyal]

I'll open another PR to add that the missing diagnostic note for DerivedObligations, then rebase this off that.

@rustbot author

[compiler-errors]

Hmmm.. thinking whether or not I'd prefer if you just fixed the ICE at the spot that the ICE occurs. Conceptually, the trait alias is its own "synthetic" impl, and most other users of ImplDerivedObligation are designed to correctly handle trait alias def ids (like method probe error reporting code).

If you're going to stick with this appproach, be careful not to introduce a bunch of other diagnostic fallout that comes from trying to "un-regress" the diagnostic regression here from using DerivedObligation...

[eggyal]

Conceptually, the trait alias is its own "synthetic" impl

Ah, okay, if that's the case then I agree we should handle this differently. Will rework in a different PR.

[rust-log-analyzer]

The job x86_64-gnu-llvm-14 failed! Check out the build log: (web) (plain)

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

Prepare all required actions
Getting action download info
Download action repository 'actions/checkout@v3' (SHA:ac593985615ec2ede58e132d2e21d2b1cbd6127c)
Download action repository 'rust-lang/simpleinfra@master' (SHA:7ea263296c702710d7fac3c6d5bccdb2895b4e79)
Complete job name: PR (x86_64-gnu-llvm-14, false, ubuntu-20.04-xl)
git config --global core.autocrlf false
shell: /usr/bin/bash --noprofile --norc -e -o pipefail {0}
env:
  CI_JOB_NAME: x86_64-gnu-llvm-14
---

---- [ui] tests/ui/traits/alias/cross-crate.rs stdout ----
diff of stderr:

5    |                 ^^^^^^^ `Rc<u32>` cannot be sent between threads safely
6    |
7    = help: the trait `Send` is not implemented for `Rc<u32>`
-    = note: required for `Rc<u32>` to implement `SendSync`
9 note: required by a bound in `use_alias`
11    |


19    |                 ^^^^^^^ `Rc<u32>` cannot be shared between threads safely
20    |
21    = help: the trait `Sync` is not implemented for `Rc<u32>`
-    = note: required for `Rc<u32>` to implement `SendSync`
23 note: required by a bound in `use_alias`
25    |


The actual stderr differed from the expected stderr.
The actual stderr differed from the expected stderr.
Actual stderr saved to /checkout/obj/build/x86_64-unknown-linux-gnu/test/ui/traits/alias/cross-crate/cross-crate.stderr
To update references, rerun the tests and pass the `--bless` flag
To only update this specific test, also pass `--test-args traits/alias/cross-crate.rs`

error: 1 errors occurred comparing output.
status: exit status: 1
command: "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/bin/rustc" "/checkout/tests/ui/traits/alias/cross-crate.rs" "-Zthreads=1" "--target=x86_64-unknown-linux-gnu" "--error-format" "json" "--json" "future-incompat" "-Ccodegen-units=1" "-Zui-testing" "-Zsimulate-remapped-rust-src-base=/rustc/FAKE_PREFIX" "-Ztranslate-remapped-path-to-local-path=no" "-Zdeduplicate-diagnostics=no" "-Cstrip=debuginfo" "--remap-path-prefix=/checkout/tests/ui=fake-test-src-base" "--emit" "metadata" "-C" "prefer-dynamic" "--out-dir" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/ui/traits/alias/cross-crate" "-A" "unused" "-Crpath" "-Cdebuginfo=0" "-Lnative=/checkout/obj/build/x86_64-unknown-linux-gnu/native/rust-test-helpers" "-L" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/ui/traits/alias/cross-crate/auxiliary"
stdout: none
--- stderr -------------------------------
error[E0277]: `Rc<u32>` cannot be sent between threads safely
  --> fake-test-src-base/traits/alias/cross-crate.rs:14:17
   |
LL |     use_alias::<Rc<u32>>();
   |                 ^^^^^^^ `Rc<u32>` cannot be sent between threads safely
   |
   = help: the trait `Send` is not implemented for `Rc<u32>`
note: required by a bound in `use_alias`
  --> fake-test-src-base/traits/alias/cross-crate.rs:10:17
   |
LL | fn use_alias<T: SendSync>() {}
   |                 ^^^^^^^^ required by this bound in `use_alias`

error[E0277]: `Rc<u32>` cannot be shared between threads safely
  --> fake-test-src-base/traits/alias/cross-crate.rs:14:17
   |
LL |     use_alias::<Rc<u32>>();
   |                 ^^^^^^^ `Rc<u32>` cannot be shared between threads safely
   |
   = help: the trait `Sync` is not implemented for `Rc<u32>`
note: required by a bound in `use_alias`
  --> fake-test-src-base/traits/alias/cross-crate.rs:10:17
Some tests failed in compiletest suite=ui mode=ui host=x86_64-unknown-linux-gnu target=x86_64-unknown-linux-gnu
   |
LL | fn use_alias<T: SendSync>() {}
   |                 ^^^^^^^^ required by this bound in `use_alias`
error: aborting due to 2 previous errors

For more information about this error, try `rustc --explain E0277`.
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[eggyal]

Speedy bot! 😂