Avoid reporting overflow in `is_impossible_method`
Fixes#100620
We're evaluating a new predicate in a different param-env than it was checked during typeck, so be more careful about handling overflow errors. Instead of using `FulfillmentCtxt`, using `InferCtxt::evaluate_obligation` by itself will give us back the overflow error, so we can throw it away properly.
This may give us more false-positives, but it doesn't regress the `<HashMap as Iterator>::rev` example that originally motivated adding `is_impossible_method` in the first place.
Coherence negative impls implied bounds
Fixes#93875
This PR is rebased on top of #100789 and it would need to include that one which is already r+ed.
r? ``@nikomatsakis``
cc ``@lcnr`` (which I've talked about 3222f420d9, I guess after you finish your reordering of modules and work with OutlivesEnvironmentEnv this commit can just be reverted).
InferCtxt tainted_by_errors_flag should be Option<ErrorGuaranteed>
Fixes#100321.
Use Cell<Option<ErrorGuaranteed>> to guarantee that we emit an error when that flag is set.
Use separate infcx to solve obligations during negative coherence
I feel like I fixed this already but I may have fixed it then forgot to push the branch...
Also fixes up some redundant param-envs being passed around (since they're already passed around in the `Obligation`)
Fixes#99662
r? ``@spastorino``
implied bounds: explicitly state which types are assumed to be wf
Adds a new query which maps each definition to the types which that definition assumes to be well formed. The intent is to make it easier to reason about implied bounds.
This change should not influence the user-facing behavior of rustc. Notably, `borrowck` still only assumes that the function signature of associated functions is well formed while `wfcheck` assumes that the both the function signature and the impl trait ref is well formed. Not sure if that by itself can trigger UB or whether it's just annoying.
As a next step, we can add `WellFormed` predicates to `predicates_of` of these items and can stop adding the wf bounds at each place which uses them. I also intend to move the computation from `assumed_wf_types` to `implied_bounds` into the `param_env` computation. This requires me to take a deeper look at `compare_predicate_entailment` which is currently somewhat weird wrt implied bounds so I am not touching this here.
r? `@nikomatsakis`
Refactor: remove unnecessary string searchings
This patch removes unnecessary string searchings for checking if function arguments have `&` and `&mut`.
Revert "Rollup merge of #97346 - JohnTitor:remove-back-compat-hacks, …
…r=oli-obk"
This reverts commit c703d11dcc, reversing
changes made to 64eb9ab869.
it didn't apply cleanly, so now it works the same for RPIT and for TAIT instead of just working for RPIT, but we should keep those in sync anyway. It also exposed a TAIT bug (see the feature gated test that now ICEs).
r? `@pnkfelix`
fixes#99536
orphan check: rationalize our handling of constants
cc `@rust-lang/types` `@rust-lang/project-const-generics` on whether you agree with this reasoning.
r? types
Keep going if normalized projection has unevaluated consts in `QueryNormalizer`
#100312 was the wrong approach, I think this is the right one.
When normalizing a type, if we see that it's a projection, we currently defer to `tcx.normalize_projection_ty`, which normalizes the projections away but doesn't touch the unevaluated constants. So now we just continue to fold the type if it has unevaluated constants so we make sure to evaluate those too, if we can.
Fixes#100217Fixes#83972Fixes#84669Fixes#86710Fixes#82268Fixes#73298
consider unnormalized types for implied bounds
extracted, and slightly modified, from #98900
The idea here is that generally, rustc is split into things which can assume its inputs are well formed[^1], and things which have verify that themselves.
Generally most predicates should only deal with well formed inputs, e.g. a `&'a &'b (): Trait` predicate should be able to assume that `'b: 'a` holds. Normalization can loosen wf requirements (see #91068) and must therefore not be used in places which still have to check well formedness. The only such place should hopefully be `WellFormed` predicates
fixes#87748 and #98543
r? `@jackh726` cc `@rust-lang/types`
[^1]: These places may still encounter non-wf inputs and have to deal with them without causing an ICE as we may check for well formedness out of order.
Don't document impossible to call default trait items on impls
Closes#100176
This only skips documenting _default_ trait items on impls, not ones that are written inside the impl block. This is a conservative approach, since I think we should document all items written in an impl block (I guess unless hidden or whatever), but the existence of this new query I added makes this easy to extend to other rustdoc cases.
