Auto merge of rust-lang#118553 - jackh726:lint-implied-bounds, r=<try>

lint incorrect implied bounds in wfcheck except for Bevy dependents

Rebase of rust-lang#109763

Additionally, special cases Bevy `ParamSet` types to not trigger the lint.

Opening for crater

r? `@ghost`

compiler/rustc_hir_analysis/src/check/check.rs

@@ -356,7 +356,7 @@ fn check_opaque_meets_bounds<'tcx>(
         // Can have different predicates to their defining use
         hir::OpaqueTyOrigin::TyAlias { .. } => {
             let wf_tys = ocx.assumed_wf_types_and_report_errors(param_env, def_id)?;
-            let implied_bounds = infcx.implied_bounds_tys(param_env, def_id, wf_tys);
+            let implied_bounds = infcx.implied_bounds_tys_compat(param_env, def_id, &wf_tys);
             let outlives_env = OutlivesEnvironment::with_bounds(param_env, implied_bounds);
             ocx.resolve_regions_and_report_errors(defining_use_anchor, &outlives_env)?;
         }

compiler/rustc_hir_analysis/src/check/compare_impl_item.rs

@@ -404,7 +404,7 @@ fn compare_method_predicate_entailment<'tcx>(
     // lifetime parameters.
     let outlives_env = OutlivesEnvironment::with_bounds(
         param_env,
-        infcx.implied_bounds_tys(param_env, impl_m_def_id, wf_tys),
+        infcx.implied_bounds_tys_compat(param_env, impl_m_def_id, &wf_tys),
     );
     let errors = infcx.resolve_regions(&outlives_env);
     if !errors.is_empty() {
@@ -880,7 +880,7 @@ pub(super) fn collect_return_position_impl_trait_in_trait_tys<'tcx>(
     // lifetime parameters.
     let outlives_env = OutlivesEnvironment::with_bounds(
         param_env,
-        infcx.implied_bounds_tys(param_env, impl_m_def_id, wf_tys),
+        infcx.implied_bounds_tys_compat(param_env, impl_m_def_id, &wf_tys),
     );
     ocx.resolve_regions_and_report_errors(impl_m_def_id, &outlives_env)?;
 
@@ -2242,7 +2242,8 @@ pub(super) fn check_type_bounds<'tcx>(
 
     // Finally, resolve all regions. This catches wily misuses of
     // lifetime parameters.
-    let implied_bounds = infcx.implied_bounds_tys(param_env, impl_ty_def_id, assumed_wf_types);
+    let implied_bounds =
+        infcx.implied_bounds_tys_compat(param_env, impl_ty_def_id, &assumed_wf_types);
     let outlives_env = OutlivesEnvironment::with_bounds(param_env, implied_bounds);
     ocx.resolve_regions_and_report_errors(impl_ty_def_id, &outlives_env)
 }

compiler/rustc_hir_analysis/src/check/compare_impl_item/refine.rs

@@ -161,7 +161,7 @@ pub(super) fn check_refining_return_position_impl_trait_in_trait<'tcx>(
     }
     let outlives_env = OutlivesEnvironment::with_bounds(
         param_env,
-        infcx.implied_bounds_tys(param_env, impl_m.def_id.expect_local(), implied_wf_types),
+        infcx.implied_bounds_tys_compat(param_env, impl_m.def_id.expect_local(), &implied_wf_types),
     );
     let errors = infcx.resolve_regions(&outlives_env);
     if !errors.is_empty() {

compiler/rustc_hir_analysis/src/check/wfcheck.rs

@@ -13,6 +13,7 @@ use rustc_infer::infer::outlives::obligations::TypeOutlives;
 use rustc_infer::infer::{self, InferCtxt, TyCtxtInferExt};
 use rustc_middle::mir::ConstraintCategory;
 use rustc_middle::query::Providers;
+use rustc_middle::ty::print::with_no_trimmed_paths;
 use rustc_middle::ty::trait_def::TraitSpecializationKind;
 use rustc_middle::ty::{
     self, AdtKind, GenericParamDefKind, ToPredicate, Ty, TyCtxt, TypeFoldable, TypeSuperVisitable,
@@ -110,8 +111,6 @@ where
 
     let assumed_wf_types = wfcx.ocx.assumed_wf_types_and_report_errors(param_env, body_def_id)?;
 
-    let implied_bounds = infcx.implied_bounds_tys(param_env, body_def_id, assumed_wf_types);
-
     let errors = wfcx.select_all_or_error();
     if !errors.is_empty() {
         let err = infcx.err_ctxt().report_fulfillment_errors(errors);
@@ -126,9 +125,60 @@ where
         }
     }
 
+    let infcx_compat = infcx.fork();
+
+    debug!(?assumed_wf_types);
+    let implied_bounds = infcx.implied_bounds_tys(param_env, &assumed_wf_types);
     let outlives_env = OutlivesEnvironment::with_bounds(param_env, implied_bounds);
 
-    wfcx.ocx.resolve_regions_and_report_errors(body_def_id, &outlives_env)?;
+    let errors = infcx.resolve_regions(&outlives_env);
+    if errors.is_empty() {
+        return Ok(());
+    }
+
+    let implied_bounds =
+        infcx_compat.implied_bounds_tys_compat(param_env, body_def_id, &assumed_wf_types);
+    let outlives_env = OutlivesEnvironment::with_bounds(param_env, implied_bounds);
+    let errors_compat = infcx_compat.resolve_regions(&outlives_env);
+    if !errors_compat.is_empty() {
+        return Err(infcx_compat.err_ctxt().report_region_errors(body_def_id, &errors_compat));
+    }
+
+    // We don't want to emit this for dependents of Bevy, for now.
+    for ty in assumed_wf_types.iter() {
+        match ty.kind() {
+            ty::Adt(def, _) => {
+                let adt_did = with_no_trimmed_paths!(infcx.tcx.def_path_str(def.0.did));
+                if adt_did.contains("ParamSet") {
+                    return Ok(());
+                }
+            }
+            _ => {}
+        }
+    }
+
+    let hir_id = tcx.local_def_id_to_hir_id(body_def_id);
+    let (lint_level, _) = tcx
+        .lint_level_at_node(rustc_session::lint::builtin::IMPLIED_BOUNDS_FROM_TRAIT_IMPL, hir_id);
+    tcx.struct_span_lint_hir(
+        rustc_session::lint::builtin::IMPLIED_BOUNDS_FROM_TRAIT_IMPL,
+        hir_id,
+        tcx.def_span(body_def_id),
+        format!("{} is missing necessary lifetime bounds", tcx.def_descr(body_def_id.into())),
+        |lint| {
+            if !lint_level.is_error() {
+                lint.note(
+                    "to get more detailed errors, use `#[deny(implied_bounds_from_trait_impl)]`",
+                )
+            } else {
+                lint.note("more concrete lifetime errors are emitted below")
+            }
+        },
+    );
+    if true || lint_level.is_error() {
+        infcx.err_ctxt().report_region_errors(body_def_id, &errors);
+    }
+
     infcx.tainted_by_errors().error_reported()
 }
 
@@ -717,7 +767,7 @@ fn resolve_regions_with_wf_tys<'tcx>(
     let infcx = tcx.infer_ctxt().build();
     let outlives_environment = OutlivesEnvironment::with_bounds(
         param_env,
-        infcx.implied_bounds_tys(param_env, id, wf_tys.clone()),
+        infcx.implied_bounds_tys_compat(param_env, id, wf_tys),
     );
     let region_bound_pairs = outlives_environment.region_bound_pairs();
 

compiler/rustc_hir_analysis/src/impl_wf_check/min_specialization.rs

@@ -202,7 +202,8 @@ fn get_impl_args(
         return Err(guar);
     }
 
-    let implied_bounds = infcx.implied_bounds_tys(param_env, impl1_def_id, assumed_wf_types);
+    let implied_bounds =
+        infcx.implied_bounds_tys_compat(param_env, impl1_def_id, &assumed_wf_types);
     let outlives_env = OutlivesEnvironment::with_bounds(param_env, implied_bounds);
     let _ = ocx.resolve_regions_and_report_errors(impl1_def_id, &outlives_env);
     let Ok(impl2_args) = infcx.fully_resolve(impl2_args) else {

compiler/rustc_lint_defs/src/builtin.rs

@@ -3388,6 +3388,7 @@ declare_lint_pass! {
         ILL_FORMED_ATTRIBUTE_INPUT,
         ILLEGAL_FLOATING_POINT_LITERAL_PATTERN,
         IMPLIED_BOUNDS_ENTAILMENT,
+        IMPLIED_BOUNDS_FROM_TRAIT_IMPL,
         INCOMPLETE_INCLUDE,
         INDIRECT_STRUCTURAL_MATCH,
         INEFFECTIVE_UNSTABLE_TRAIT_IMPL,
@@ -4620,3 +4621,44 @@ declare_lint! {
         reference: "issue #115010 <https://github.com/rust-lang/rust/issues/115010>",
     };
 }
+
+declare_lint! {
+    /// The `implied_bounds_from_trait_impl` lint detects
+    /// a compiler bug allowed some code to assume invalid implied lifetime bounds.
+    ///
+    /// ### Example
+    ///
+    /// ```rust,compile_fail
+    /// #![deny(implied_bounds_from_trait_impl)]
+    ///
+    /// trait Trait {
+    ///     type Assoc;
+    /// }
+    ///
+    /// impl<X: 'static> Trait for (X,) {
+    ///     type Assoc = ();
+    /// }
+    ///
+    /// struct Foo<T: Trait>(T)
+    /// where
+    ///     T::Assoc: Clone; // any bound using `T::Assoc`
+    ///
+    /// fn func(foo: Foo<(&str,)>) {
+    ///     let _: &'static str = foo.0.0;
+    /// }
+    /// ```
+    ///
+    /// {{produces}}
+    ///
+    /// ### Explanation
+    ///
+    /// FIXME: explanataion
+    ///
+    pub IMPLIED_BOUNDS_FROM_TRAIT_IMPL,
+    Warn,
+    "item uses illegal implied bounds derived from a trait impl",
+    @future_incompatible = FutureIncompatibleInfo {
+        reason: FutureIncompatibilityReason::FutureReleaseErrorDontReportInDeps,
+        reference: "issue #109628 <https://github.com/rust-lang/rust/issues/109628>",
+    };
+}

compiler/rustc_middle/src/arena.rs

@@ -53,7 +53,7 @@ macro_rules! arena_types {
                         rustc_middle::traits::query::NormalizationResult<'tcx>
                     >
                 >,
-            [] implied_outlives_bounds:
+            [] implied_outlives_bounds_compat:
                 rustc_middle::infer::canonical::Canonical<'tcx,
                     rustc_middle::infer::canonical::QueryResponse<'tcx,
                         Vec<rustc_middle::traits::query::OutlivesBound<'tcx>>

compiler/rustc_middle/src/query/erase.rs

@@ -74,6 +74,10 @@ impl<T> EraseType for Result<&'_ T, traits::query::NoSolution> {
     type Result = [u8; size_of::<Result<&'static (), traits::query::NoSolution>>()];
 }
 
+impl<T> EraseType for Result<&'_ [T], traits::query::NoSolution> {
+    type Result = [u8; size_of::<Result<&'static [()], traits::query::NoSolution>>()];
+}
+
 impl<T> EraseType for Result<&'_ T, rustc_errors::ErrorGuaranteed> {
     type Result = [u8; size_of::<Result<&'static (), rustc_errors::ErrorGuaranteed>>()];
 }

compiler/rustc_middle/src/query/mod.rs

@@ -1953,7 +1953,7 @@ rustc_queries! {
         desc { "normalizing `{}`", goal.value }
     }
 
-    query implied_outlives_bounds(
+    query implied_outlives_bounds_compat(
         goal: CanonicalTyGoal<'tcx>
     ) -> Result<
         &'tcx Canonical<'tcx, canonical::QueryResponse<'tcx, Vec<OutlivesBound<'tcx>>>>,
@@ -1962,6 +1962,15 @@ rustc_queries! {
         desc { "computing implied outlives bounds for `{}`", goal.value.value }
     }
 
+    query implied_outlives_bounds(
+        goal: ty::ParamEnvAnd<'tcx, Ty<'tcx>>
+    ) -> Result<
+        &'tcx [OutlivesBound<'tcx>],
+        NoSolution,
+    > {
+        desc { "computing implied outlives bounds v2 for `{}`", goal.value }
+    }
+
     /// Do not call this query directly:
     /// invoke `DropckOutlives::new(dropped_ty)).fully_perform(typeck.infcx)` instead.
     query dropck_outlives(

compiler/rustc_middle/src/traits/query.rs

@@ -191,7 +191,7 @@ pub struct NormalizationResult<'tcx> {
 /// case they are called implied bounds). They are fed to the
 /// `OutlivesEnv` which in turn is supplied to the region checker and
 /// other parts of the inference system.
-#[derive(Clone, Debug, TypeFoldable, TypeVisitable, HashStable)]
+#[derive(Copy, Clone, Debug, TypeFoldable, TypeVisitable, HashStable)]
 pub enum OutlivesBound<'tcx> {
     RegionSubRegion(ty::Region<'tcx>, ty::Region<'tcx>),
     RegionSubParam(ty::Region<'tcx>, ty::ParamTy),

compiler/rustc_trait_selection/src/traits/misc.rs

@@ -191,10 +191,10 @@ pub fn all_fields_implement_trait<'tcx>(
             // Check regions assuming the self type of the impl is WF
             let outlives_env = OutlivesEnvironment::with_bounds(
                 param_env,
-                infcx.implied_bounds_tys(
+                infcx.implied_bounds_tys_compat(
                     param_env,
                     parent_cause.body_id,
-                    FxIndexSet::from_iter([self_type]),
+                    &FxIndexSet::from_iter([self_type]),
                 ),
             );
             let errors = infcx.resolve_regions(&outlives_env);

compiler/rustc_trait_selection/src/traits/outlives_bounds.rs

@@ -9,20 +9,27 @@ use rustc_span::def_id::LocalDefId;
 
 pub use rustc_middle::traits::query::OutlivesBound;
 
+pub type BoundsCompat<'a, 'tcx: 'a> = impl Iterator<Item = OutlivesBound<'tcx>> + 'a;
 pub type Bounds<'a, 'tcx: 'a> = impl Iterator<Item = OutlivesBound<'tcx>> + 'a;
 pub trait InferCtxtExt<'a, 'tcx> {
-    fn implied_outlives_bounds(
+    fn implied_outlives_bounds_compat(
         &self,
         param_env: ty::ParamEnv<'tcx>,
         body_id: LocalDefId,
         ty: Ty<'tcx>,
     ) -> Vec<OutlivesBound<'tcx>>;
 
-    fn implied_bounds_tys(
+    fn implied_bounds_tys_compat(
         &'a self,
         param_env: ty::ParamEnv<'tcx>,
         body_id: LocalDefId,
-        tys: FxIndexSet<Ty<'tcx>>,
+        tys: &'a FxIndexSet<Ty<'tcx>>,
+    ) -> BoundsCompat<'a, 'tcx>;
+
+    fn implied_bounds_tys(
+        &'a self,
+        param_env: ty::ParamEnv<'tcx>,
+        tys: &'a FxIndexSet<Ty<'tcx>>,
     ) -> Bounds<'a, 'tcx>;
 }
 
@@ -47,7 +54,7 @@ impl<'a, 'tcx: 'a> InferCtxtExt<'a, 'tcx> for InferCtxt<'tcx> {
     ///   into the inference context with this body-id.
     /// - `ty`, the type that we are supposed to assume is WF.
     #[instrument(level = "debug", skip(self, param_env, body_id), ret)]
-    fn implied_outlives_bounds(
+    fn implied_outlives_bounds_compat(
         &self,
         param_env: ty::ParamEnv<'tcx>,
         body_id: LocalDefId,
@@ -67,7 +74,7 @@ impl<'a, 'tcx: 'a> InferCtxtExt<'a, 'tcx> for InferCtxt<'tcx> {
         let mut canonical_var_values = OriginalQueryValues::default();
         let canonical_ty =
             self.canonicalize_query_keep_static(param_env.and(ty), &mut canonical_var_values);
-        let Ok(canonical_result) = self.tcx.implied_outlives_bounds(canonical_ty) else {
+        let Ok(canonical_result) = self.tcx.implied_outlives_bounds_compat(canonical_ty) else {
             return vec![];
         };
 
@@ -113,20 +120,39 @@ impl<'a, 'tcx: 'a> InferCtxtExt<'a, 'tcx> for InferCtxt<'tcx> {
             if !errors.is_empty() {
                 self.tcx.sess.span_delayed_bug(
                     span,
-                    "implied_outlives_bounds failed to solve obligations from instantiation",
+                    "implied_outlives_bounds_compat failed to solve obligations from instantiation",
                 );
             }
         };
 
         bounds
     }
 
-    fn implied_bounds_tys(
+    fn implied_bounds_tys_compat(
         &'a self,
         param_env: ParamEnv<'tcx>,
         body_id: LocalDefId,
-        tys: FxIndexSet<Ty<'tcx>>,
+        tys: &'a FxIndexSet<Ty<'tcx>>,
+    ) -> BoundsCompat<'a, 'tcx> {
+        tys.iter().flat_map(move |ty| self.implied_outlives_bounds_compat(param_env, body_id, *ty))
+    }
+
+    fn implied_bounds_tys(
+        &'a self,
+        param_env: ParamEnv<'tcx>,
+        tys: &'a FxIndexSet<Ty<'tcx>>,
     ) -> Bounds<'a, 'tcx> {
-        tys.into_iter().flat_map(move |ty| self.implied_outlives_bounds(param_env, body_id, ty))
+        tys.iter()
+            .flat_map(move |&ty| {
+                let ty = self.resolve_vars_if_possible(ty);
+                let ty = OpportunisticRegionResolver::new(self).fold_ty(ty);
+
+                if ty.has_infer() {
+                    return &[] as &[OutlivesBound<'_>];
+                }
+
+                self.tcx.implied_outlives_bounds(param_env.and(ty)).unwrap_or(&[])
+            })
+            .copied()
     }
 }