Use != Positive rather than == Negative

Feels more complete, and for ImplPolarity has the side-effect of making
sure we also handle reservation impls correctly

Author: compiler-errors

compiler/rustc_hir_analysis/src/astconv/mod.rs

@@ -682,7 +682,7 @@ impl<'tcx> dyn AstConv<'tcx> + '_ {
             // Don't register additional associated type bounds for negative bounds,
             // since we should have emitten an error for them earlier, and they will
             // not be well-formed!
-            if polarity == ty::PredicatePolarity::Negative {
+            if polarity != ty::PredicatePolarity::Positive {
                 assert!(
                     self.tcx().dcx().has_errors().is_some(),
                     "negative trait bounds should not have bindings",

compiler/rustc_hir_typeck/src/method/suggest.rs

@@ -3367,7 +3367,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                                 "inherent impls can't be candidates, only trait impls can be",
                             )
                         })
-                        .filter(|header| header.polarity == ty::ImplPolarity::Negative)
+                        .filter(|header| header.polarity != ty::ImplPolarity::Positive)
                         .any(|header| {
                             let imp = header.trait_ref.instantiate_identity();
                             let imp_simp =

compiler/rustc_infer/src/traits/util.rs

@@ -270,7 +270,7 @@ impl<'tcx, O: Elaboratable<'tcx>> Elaborator<'tcx, O> {
         match bound_clause.skip_binder() {
             ty::ClauseKind::Trait(data) => {
                 // Negative trait bounds do not imply any supertrait bounds
-                if data.polarity == ty::PredicatePolarity::Negative {
+                if data.polarity != ty::PredicatePolarity::Positive {
                     return;
                 }
                 // Get predicates implied by the trait, or only super predicates if we only care about self predicates.

compiler/rustc_trait_selection/src/traits/auto_trait.rs

@@ -295,7 +295,7 @@ impl<'tcx> AutoTraitFinder<'tcx> {
                     }) = impl_source
                     {
                         // Blame 'tidy' for the weird bracket placement.
-                        if infcx.tcx.impl_polarity(*impl_def_id) == ty::ImplPolarity::Negative {
+                        if infcx.tcx.impl_polarity(*impl_def_id) != ty::ImplPolarity::Positive {
                             debug!(
                                 "evaluate_nested_obligations: found explicit negative impl\
                                         {:?}, bailing out",

compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs

@@ -245,7 +245,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
         associated_ty: Option<(&'static str, Ty<'tcx>)>,
         mut body_id: LocalDefId,
     ) {
-        if trait_pred.skip_binder().polarity == ty::PredicatePolarity::Negative {
+        if trait_pred.skip_binder().polarity != ty::PredicatePolarity::Positive {
             return;
         }
 

compiler/rustc_trait_selection/src/traits/error_reporting/type_err_ctxt_ext.rs

@@ -1907,7 +1907,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
             .all_impls(trait_pred.def_id())
             .filter_map(|def_id| {
                 let imp = self.tcx.impl_trait_header(def_id).unwrap();
-                if imp.polarity == ty::ImplPolarity::Negative
+                if imp.polarity != ty::ImplPolarity::Positive
                     || !self.tcx.is_user_visible_dep(def_id.krate)
                 {
                     return None;