Auto merge of #100677 - matthiaskrgr:rollup-au41ho1, r=matthiaskrgr

Rollup of 15 pull requests

Successful merges:

 - #99474 (Rustdoc json tests: New `@hasexact` test command)
 - #99972 (interpret: only consider 1-ZST when searching for receiver)
 - #100018 (Clean up `LitKind`)
 - #100379 (triagebot: add translation-related mention groups)
 - #100389 (Do not report cycle error when inferring return type for suggestion)
 - #100489 (`is_knowable` use `Result` instead of `Option`)
 - #100532 (unwind: don't build dependency when building for Miri)
 - #100608 (needless separation of impl blocks)
 - #100621 (Pass +atomics-32 feature for {arm,thumb}v4t-none-eabi)
 - #100646 (Migrate emoji identifier diagnostics to `SessionDiagnostic` in rustc_interface)
 - #100652 (Remove deferred sized checks (make them eager))
 - #100655 (Update books)
 - #100656 (Update cargo)
 - #100660 (Fixed a few documentation errors)
 - #100661 (Fixed a few documentation errors)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup

3 files changed, 8 insertions, 8 deletions

diff --git a/compiler/rustc_trait_selection/src/traits/coherence.rs b/compiler/rustc_trait_selection/src/traits/coherence.rs
index 9bb41b900b8..985600d9ebc 100644
--- a/compiler/rustc_trait_selection/src/traits/coherence.rs
+++ b/compiler/rustc_trait_selection/src/traits/coherence.rs
@@ -404,12 +404,12 @@ fn resolve_negative_obligation<'cx, 'tcx>(
 pub fn trait_ref_is_knowable<'tcx>(
     tcx: TyCtxt<'tcx>,
     trait_ref: ty::TraitRef<'tcx>,
-) -> Option<Conflict> {
+) -> Result<(), Conflict> {
     debug!("trait_ref_is_knowable(trait_ref={:?})", trait_ref);
     if orphan_check_trait_ref(tcx, trait_ref, InCrate::Remote).is_ok() {
         // A downstream or cousin crate is allowed to implement some
         // substitution of this trait-ref.
-        return Some(Conflict::Downstream);
+        return Err(Conflict::Downstream);
     }
 
     if trait_ref_is_local_or_fundamental(tcx, trait_ref) {
@@ -418,7 +418,7 @@ pub fn trait_ref_is_knowable<'tcx>(
         // allowed to implement a substitution of this trait ref, which
         // means impls could only come from dependencies of this crate,
         // which we already know about.
-        return None;
+        return Ok(());
     }
 
     // This is a remote non-fundamental trait, so if another crate
@@ -431,10 +431,10 @@ pub fn trait_ref_is_knowable<'tcx>(
     // we are an owner.
     if orphan_check_trait_ref(tcx, trait_ref, InCrate::Local).is_ok() {
         debug!("trait_ref_is_knowable: orphan check passed");
-        None
+        Ok(())
     } else {
         debug!("trait_ref_is_knowable: nonlocal, nonfundamental, unowned");
-        Some(Conflict::Upstream)
+        Err(Conflict::Upstream)
     }
 }
 
diff --git a/compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs b/compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs
index 50e9b95a445..d67bd6292b4 100644
--- a/compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs
+++ b/compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs
@@ -75,7 +75,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
         &mut self,
         stack: &TraitObligationStack<'o, 'tcx>,
     ) -> SelectionResult<'tcx, SelectionCandidate<'tcx>> {
-        if let Some(conflict) = self.is_knowable(stack) {
+        if let Err(conflict) = self.is_knowable(stack) {
             debug!("coherence stage: not knowable");
             if self.intercrate_ambiguity_causes.is_some() {
                 debug!("evaluate_stack: intercrate_ambiguity_causes is some");
diff --git a/compiler/rustc_trait_selection/src/traits/select/mod.rs b/compiler/rustc_trait_selection/src/traits/select/mod.rs
index c01ac197991..46b50dd92f1 100644
--- a/compiler/rustc_trait_selection/src/traits/select/mod.rs
+++ b/compiler/rustc_trait_selection/src/traits/select/mod.rs
@@ -1265,11 +1265,11 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
         Ok(Some(candidate))
     }
 
-    fn is_knowable<'o>(&mut self, stack: &TraitObligationStack<'o, 'tcx>) -> Option<Conflict> {
+    fn is_knowable<'o>(&mut self, stack: &TraitObligationStack<'o, 'tcx>) -> Result<(), Conflict> {
         debug!("is_knowable(intercrate={:?})", self.intercrate);
 
         if !self.intercrate || stack.obligation.polarity() == ty::ImplPolarity::Negative {
-            return None;
+            return Ok(());
         }
 
         let obligation = &stack.obligation;