Rollup merge of rust-lang#137633 - compiler-errors:no-implied-bounds-hack-unless-bevy, r=lcnr

Only use implied bounds hack if bevy, and use deeply normalize in implied bounds hack

Consolidates the implied bounds computation mode into a single function, which deeply normalizes, and if it's in **compat** mode (for bevy), it extracts outlives bounds from the infcx.

Previously, we were using the implied bounds compat mode in two cases:
1. During WF, if it detects `ParamSet`
2. EVERYWHERE ELSE (lol) -- e.g. borrowck, predicate entailment, etc.

While I think this is fine, and the net effect was just that we emitted fewer diagnostics, it makes me uncomfortable that all crates were using the supposed "compat" code.

Fixes rust-lang#137767

Author: jieyouxu

compiler/rustc_hir_analysis/src/check/wfcheck.rs

@@ -126,13 +126,14 @@ where
 
     let infcx_compat = infcx.fork();
 
-    // We specifically want to call the non-compat version of `implied_bounds_tys`; we do this always.
+    // We specifically want to *disable* the implied bounds hack, first,
+    // so we can detect when failures are due to bevy's implied bounds.
     let outlives_env = OutlivesEnvironment::new_with_implied_bounds_compat(
         &infcx,
         body_def_id,
         param_env,
         assumed_wf_types.iter().copied(),
-        false,
+        true,
     );
 
     lint_redundant_lifetimes(tcx, body_def_id, &outlives_env);
@@ -142,53 +143,22 @@ where
         return Ok(());
     }
 
-    let is_bevy = assumed_wf_types.visit_with(&mut ContainsBevyParamSet { tcx }).is_break();
-
-    // If we have set `no_implied_bounds_compat`, then do not attempt compatibility.
-    // We could also just always enter if `is_bevy`, and call `implied_bounds_tys`,
-    // but that does result in slightly more work when this option is set and
-    // just obscures what we mean here anyways. Let's just be explicit.
-    if is_bevy && !infcx.tcx.sess.opts.unstable_opts.no_implied_bounds_compat {
-        let outlives_env = OutlivesEnvironment::new_with_implied_bounds_compat(
-            &infcx,
-            body_def_id,
-            param_env,
-            assumed_wf_types,
-            true,
-        );
-        let errors_compat = infcx_compat.resolve_regions_with_outlives_env(&outlives_env);
-        if errors_compat.is_empty() {
-            Ok(())
-        } else {
-            Err(infcx_compat.err_ctxt().report_region_errors(body_def_id, &errors_compat))
-        }
+    let outlives_env = OutlivesEnvironment::new_with_implied_bounds_compat(
+        &infcx_compat,
+        body_def_id,
+        param_env,
+        assumed_wf_types,
+        // Don't *disable* the implied bounds hack; though this will only apply
+        // the implied bounds hack if this contains `bevy_ecs`'s `ParamSet` type.
+        false,
+    );
+    let errors_compat = infcx_compat.resolve_regions_with_outlives_env(&outlives_env);
+    if errors_compat.is_empty() {
+        // FIXME: Once we fix bevy, this would be the place to insert a warning
+        // to upgrade bevy.
+        Ok(())
     } else {
-        Err(infcx.err_ctxt().report_region_errors(body_def_id, &errors))
-    }
-}
-
-struct ContainsBevyParamSet<'tcx> {
-    tcx: TyCtxt<'tcx>,
-}
-
-impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for ContainsBevyParamSet<'tcx> {
-    type Result = ControlFlow<()>;
-
-    fn visit_ty(&mut self, t: Ty<'tcx>) -> Self::Result {
-        // We only care to match `ParamSet<T>` or `&ParamSet<T>`.
-        match t.kind() {
-            ty::Adt(def, _) => {
-                if self.tcx.item_name(def.did()) == sym::ParamSet
-                    && self.tcx.crate_name(def.did().krate) == sym::bevy_ecs
-                {
-                    return ControlFlow::Break(());
-                }
-            }
-            ty::Ref(_, ty, _) => ty.visit_with(self)?,
-            _ => {}
-        }
-
-        ControlFlow::Continue(())
+        Err(infcx_compat.err_ctxt().report_region_errors(body_def_id, &errors_compat))
     }
 }
 

compiler/rustc_middle/src/query/keys.rs

@@ -508,6 +508,14 @@ impl<'tcx, T: Clone> Key for CanonicalQueryInput<'tcx, T> {
     }
 }
 
+impl<'tcx, T: Clone> Key for (CanonicalQueryInput<'tcx, T>, bool) {
+    type Cache<V> = DefaultCache<Self, V>;
+
+    fn default_span(&self, _tcx: TyCtxt<'_>) -> Span {
+        DUMMY_SP
+    }
+}
+
 impl Key for (Symbol, u32, u32) {
     type Cache<V> = DefaultCache<Self, V>;
 

compiler/rustc_middle/src/query/mod.rs

@@ -2262,22 +2262,13 @@ rustc_queries! {
         desc { "normalizing `{}`", goal.value }
     }
 
-    query implied_outlives_bounds_compat(
-        goal: CanonicalImpliedOutlivesBoundsGoal<'tcx>
-    ) -> Result<
-        &'tcx Canonical<'tcx, canonical::QueryResponse<'tcx, Vec<OutlivesBound<'tcx>>>>,
-        NoSolution,
-    > {
-        desc { "computing implied outlives bounds for `{}`", goal.canonical.value.value.ty }
-    }
-
     query implied_outlives_bounds(
-        goal: CanonicalImpliedOutlivesBoundsGoal<'tcx>
+        key: (CanonicalImpliedOutlivesBoundsGoal<'tcx>, bool)
     ) -> Result<
         &'tcx Canonical<'tcx, canonical::QueryResponse<'tcx, Vec<OutlivesBound<'tcx>>>>,
         NoSolution,
     > {
-        desc { "computing implied outlives bounds v2 for `{}`", goal.canonical.value.value.ty }
+        desc { "computing implied outlives bounds for `{}` (hack disabled = {:?})", key.0.canonical.value.value.ty, key.1 }
     }
 
     /// Do not call this query directly:

compiler/rustc_trait_selection/src/regions.rs

@@ -17,21 +17,15 @@ impl<'tcx> OutlivesEnvironment<'tcx> {
         param_env: ty::ParamEnv<'tcx>,
         assumed_wf_tys: impl IntoIterator<Item = Ty<'tcx>>,
     ) -> Self {
-        Self::new_with_implied_bounds_compat(
-            infcx,
-            body_id,
-            param_env,
-            assumed_wf_tys,
-            !infcx.tcx.sess.opts.unstable_opts.no_implied_bounds_compat,
-        )
+        Self::new_with_implied_bounds_compat(infcx, body_id, param_env, assumed_wf_tys, false)
     }
 
     fn new_with_implied_bounds_compat(
         infcx: &InferCtxt<'tcx>,
         body_id: LocalDefId,
         param_env: ty::ParamEnv<'tcx>,
         assumed_wf_tys: impl IntoIterator<Item = Ty<'tcx>>,
-        implied_bounds_compat: bool,
+        disable_implied_bounds_hack: bool,
     ) -> Self {
         let mut bounds = vec![];
 
@@ -59,11 +53,11 @@ impl<'tcx> OutlivesEnvironment<'tcx> {
         OutlivesEnvironment::from_normalized_bounds(
             param_env,
             bounds,
-            infcx.implied_bounds_tys_with_compat(
+            infcx.implied_bounds_tys(
                 body_id,
                 param_env,
                 assumed_wf_tys,
-                implied_bounds_compat,
+                disable_implied_bounds_hack,
             ),
         )
     }

compiler/rustc_trait_selection/src/traits/outlives_bounds.rs

@@ -36,7 +36,7 @@ fn implied_outlives_bounds<'a, 'tcx>(
     param_env: ty::ParamEnv<'tcx>,
     body_id: LocalDefId,
     ty: Ty<'tcx>,
-    compat: bool,
+    disable_implied_bounds_hack: bool,
 ) -> Vec<OutlivesBound<'tcx>> {
     let ty = infcx.resolve_vars_if_possible(ty);
     let ty = OpportunisticRegionResolver::new(infcx).fold_ty(ty);
@@ -52,11 +52,8 @@ fn implied_outlives_bounds<'a, 'tcx>(
     let mut canonical_var_values = OriginalQueryValues::default();
     let input = ImpliedOutlivesBounds { ty };
     let canonical = infcx.canonicalize_query(param_env.and(input), &mut canonical_var_values);
-    let implied_bounds_result = if compat {
-        infcx.tcx.implied_outlives_bounds_compat(canonical)
-    } else {
-        infcx.tcx.implied_outlives_bounds(canonical)
-    };
+    let implied_bounds_result =
+        infcx.tcx.implied_outlives_bounds((canonical, disable_implied_bounds_hack));
     let Ok(canonical_result) = implied_bounds_result else {
         return vec![];
     };
@@ -110,14 +107,15 @@ fn implied_outlives_bounds<'a, 'tcx>(
 impl<'tcx> InferCtxt<'tcx> {
     /// Do *NOT* call this directly. You probably want to construct a `OutlivesEnvironment`
     /// instead if you're interested in the implied bounds for a given signature.
-    fn implied_bounds_tys_with_compat<Tys: IntoIterator<Item = Ty<'tcx>>>(
+    fn implied_bounds_tys<Tys: IntoIterator<Item = Ty<'tcx>>>(
         &self,
         body_id: LocalDefId,
         param_env: ParamEnv<'tcx>,
         tys: Tys,
-        compat: bool,
+        disable_implied_bounds_hack: bool,
     ) -> impl Iterator<Item = OutlivesBound<'tcx>> {
-        tys.into_iter()
-            .flat_map(move |ty| implied_outlives_bounds(self, param_env, body_id, ty, compat))
+        tys.into_iter().flat_map(move |ty| {
+            implied_outlives_bounds(self, param_env, body_id, ty, disable_implied_bounds_hack)
+        })
     }
 }