misc stuff from reading VerifyBound building logic

compiler/rustc_borrowck/src/region_infer/mod.rs

@@ -181,7 +181,7 @@ pub(crate) enum Cause {
 ///
 /// For more information about this translation, see
 /// `InferCtxt::process_registered_region_obligations` and
-/// `InferCtxt::type_must_outlive` in `rustc_infer::infer::InferCtxt`.
+/// [`rustc_infer::infer::outlives::obligations::type_must_outlive`].
 #[derive(Clone, Debug)]
 pub(crate) struct TypeTest<'tcx> {
     /// The type `T` that must outlive the region.
@@ -837,8 +837,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
         lub
     }
 
-    /// Tests if `test` is true when applied to `lower_bound` at
-    /// `point`.
+    /// Tests if `generic_ty: lower_bound` holds by evaluating `verify_bound`
     fn eval_verify_bound(
         &self,
         infcx: &InferCtxt<'tcx>,

compiler/rustc_borrowck/src/type_check/constraint_conversion.rs

@@ -3,7 +3,9 @@ use rustc_hir::def_id::LocalDefId;
 use rustc_infer::infer::SubregionOrigin;
 use rustc_infer::infer::canonical::QueryRegionConstraints;
 use rustc_infer::infer::outlives::env::RegionBoundPairs;
-use rustc_infer::infer::outlives::obligations::{TypeOutlives, TypeOutlivesDelegate};
+use rustc_infer::infer::outlives::obligations::{
+    OutlivesHandlingDelegate, TypeOutlivesOpCtxt, type_must_outlive,
+};
 use rustc_infer::infer::region_constraints::{GenericKind, VerifyBound};
 use rustc_infer::traits::query::type_op::DeeplyNormalize;
 use rustc_middle::bug;
@@ -191,14 +193,14 @@ impl<'a, 'tcx> ConstraintConversion<'a, 'tcx> {
                         // we don't actually use this for anything, but
                         // the `TypeOutlives` code needs an origin.
                         let origin = SubregionOrigin::RelateParamBound(self.span, t1, None);
-                        TypeOutlives::new(
-                            &mut *self,
-                            tcx,
-                            region_bound_pairs,
-                            Some(implicit_region_bound),
-                            known_type_outlives_obligations,
-                        )
-                        .type_must_outlive(
+                        type_must_outlive(
+                            &mut TypeOutlivesOpCtxt::new(
+                                &mut *self,
+                                tcx,
+                                region_bound_pairs,
+                                Some(implicit_region_bound),
+                                known_type_outlives_obligations,
+                            ),
                             origin,
                             t1,
                             r2,
@@ -302,7 +304,7 @@ impl<'a, 'tcx> ConstraintConversion<'a, 'tcx> {
     }
 }
 
-impl<'a, 'b, 'tcx> TypeOutlivesDelegate<'tcx> for &'a mut ConstraintConversion<'b, 'tcx> {
+impl<'a, 'b, 'tcx> OutlivesHandlingDelegate<'tcx> for &'a mut ConstraintConversion<'b, 'tcx> {
     fn push_sub_region_constraint(
         &mut self,
         _origin: SubregionOrigin<'tcx>,

compiler/rustc_hir_analysis/src/outlives/utils.rs

@@ -1,9 +1,8 @@
 use rustc_data_structures::fx::FxIndexMap;
-use rustc_middle::ty::outlives::{Component, push_outlives_components};
+use rustc_middle::ty::outlives::{Component, compute_outlives_components};
 use rustc_middle::ty::{self, GenericArg, GenericArgKind, Region, Ty, TyCtxt};
 use rustc_middle::{bug, span_bug};
 use rustc_span::Span;
-use smallvec::smallvec;
 
 /// Tracks the `T: 'a` or `'a: 'a` predicates that we have inferred
 /// must be added to the struct header.
@@ -33,8 +32,7 @@ pub(crate) fn insert_outlives_predicate<'tcx>(
             //
             // Or if within `struct Foo<U>` you had `T = Vec<U>`, then
             // we would want to add `U: 'outlived_region`
-            let mut components = smallvec![];
-            push_outlives_components(tcx, ty, &mut components);
+            let components = compute_outlives_components(tcx, ty);
             for component in components {
                 match component {
                     Component::Region(r) => {

compiler/rustc_infer/src/infer/outlives/mod.rs

@@ -2,21 +2,21 @@
 
 use rustc_data_structures::undo_log::UndoLogs;
 use rustc_middle::traits::query::{NoSolution, OutlivesBound};
-use rustc_middle::ty;
-use tracing::instrument;
+use rustc_middle::ty::{self, Region, Ty, TypeVisitableExt};
+use tracing::{debug, instrument};
 
 use self::env::OutlivesEnvironment;
 use super::region_constraints::{RegionConstraintData, UndoLog};
 use super::{InferCtxt, RegionResolutionError, SubregionOrigin};
 use crate::infer::free_regions::RegionRelations;
-use crate::infer::lexical_region_resolve;
 use crate::infer::region_constraints::ConstraintKind;
+use crate::infer::{TypeOutlivesConstraint, lexical_region_resolve};
+use crate::traits::{ObligationCause, ObligationCauseCode};
 
 pub mod env;
 pub mod for_liveness;
 pub mod obligations;
 pub mod test_type_match;
-pub(crate) mod verify;
 
 #[instrument(level = "debug", skip(param_env), ret)]
 pub fn explicit_outlives_bounds<'tcx>(
@@ -31,6 +31,88 @@ pub fn explicit_outlives_bounds<'tcx>(
 }
 
 impl<'tcx> InferCtxt<'tcx> {
+    pub fn register_outlives_constraint(
+        &self,
+        ty::OutlivesPredicate(arg, r2): ty::ArgOutlivesPredicate<'tcx>,
+        cause: &ObligationCause<'tcx>,
+    ) {
+        match arg.kind() {
+            ty::GenericArgKind::Lifetime(r1) => {
+                self.register_region_outlives_constraint(ty::OutlivesPredicate(r1, r2), cause);
+            }
+            ty::GenericArgKind::Type(ty1) => {
+                self.register_type_outlives_constraint(ty1, r2, cause);
+            }
+            ty::GenericArgKind::Const(_) => unreachable!(),
+        }
+    }
+
+    pub fn register_region_outlives_constraint(
+        &self,
+        ty::OutlivesPredicate(r_a, r_b): ty::RegionOutlivesPredicate<'tcx>,
+        cause: &ObligationCause<'tcx>,
+    ) {
+        let origin = SubregionOrigin::from_obligation_cause(cause, || {
+            SubregionOrigin::RelateRegionParamBound(cause.span, None)
+        });
+        // `'a: 'b` ==> `'b <= 'a`
+        self.sub_regions(origin, r_b, r_a);
+    }
+
+    /// Registers that the given region obligation must be resolved
+    /// from within the scope of `body_id`. These regions are enqueued
+    /// and later processed by regionck, when full type information is
+    /// available (see `region_obligations` field for more
+    /// information).
+    #[instrument(level = "debug", skip(self))]
+    pub fn register_type_outlives_constraint_inner(
+        &self,
+        obligation: TypeOutlivesConstraint<'tcx>,
+    ) {
+        let mut inner = self.inner.borrow_mut();
+        inner.undo_log.push(crate::infer::UndoLog::PushTypeOutlivesConstraint);
+        inner.region_obligations.push(obligation);
+    }
+
+    pub fn register_type_outlives_constraint(
+        &self,
+        sup_type: Ty<'tcx>,
+        sub_region: Region<'tcx>,
+        cause: &ObligationCause<'tcx>,
+    ) {
+        // `is_global` means the type has no params, infer, placeholder, or non-`'static`
+        // free regions. If the type has none of these things, then we can skip registering
+        // this outlives obligation since it has no components which affect lifetime
+        // checking in an interesting way.
+        if sup_type.is_global() {
+            return;
+        }
+
+        debug!(?sup_type, ?sub_region, ?cause);
+        let origin = SubregionOrigin::from_obligation_cause(cause, || {
+            SubregionOrigin::RelateParamBound(
+                cause.span,
+                sup_type,
+                match cause.code().peel_derives() {
+                    ObligationCauseCode::WhereClause(_, span)
+                    | ObligationCauseCode::WhereClauseInExpr(_, span, ..)
+                    | ObligationCauseCode::OpaqueTypeBound(span, _)
+                        if !span.is_dummy() =>
+                    {
+                        Some(*span)
+                    }
+                    _ => None,
+                },
+            )
+        });
+
+        self.register_type_outlives_constraint_inner(TypeOutlivesConstraint {
+            sup_type,
+            sub_region,
+            origin,
+        });
+    }
+
     /// Process the region constraints and return any errors that
     /// result. After this, no more unification operations should be
     /// done -- or the compiler will panic -- but it is legal to use
@@ -89,6 +171,27 @@ impl<'tcx> InferCtxt<'tcx> {
         errors
     }
 
+    /// Trait queries just want to pass back type obligations "as is"
+    pub fn take_registered_region_obligations(&self) -> Vec<TypeOutlivesConstraint<'tcx>> {
+        assert!(!self.in_snapshot(), "cannot take registered region obligations in a snapshot");
+        std::mem::take(&mut self.inner.borrow_mut().region_obligations)
+    }
+
+    pub fn clone_registered_region_obligations(&self) -> Vec<TypeOutlivesConstraint<'tcx>> {
+        self.inner.borrow().region_obligations.clone()
+    }
+
+    pub fn register_region_assumption(&self, assumption: ty::ArgOutlivesPredicate<'tcx>) {
+        let mut inner = self.inner.borrow_mut();
+        inner.undo_log.push(crate::infer::UndoLog::PushRegionAssumption);
+        inner.region_assumptions.push(assumption);
+    }
+
+    pub fn take_registered_region_assumptions(&self) -> Vec<ty::ArgOutlivesPredicate<'tcx>> {
+        assert!(!self.in_snapshot(), "cannot take registered region assumptions in a snapshot");
+        std::mem::take(&mut self.inner.borrow_mut().region_assumptions)
+    }
+
     /// Obtains (and clears) the current set of region
     /// constraints. The inference context is still usable: further
     /// unifications will simply add new constraints.