Auto merge of rust-lang#138785 - lcnr:typing-mode-borrowck, r=<try>

add `TypingMode::Borrowck`

Still not quite ready

Based on rust-lang#138492 and rust-lang#138719

r? `@compiler-errors` `@oli-obk`

Author: bors

compiler/rustc_borrowck/src/nll.rs

@@ -6,16 +6,14 @@ use std::str::FromStr;
 use std::{env, io};
 
 use polonius_engine::{Algorithm, Output};
-use rustc_data_structures::fx::FxIndexMap;
-use rustc_hir::def_id::LocalDefId;
 use rustc_index::IndexSlice;
 use rustc_middle::mir::pretty::{PrettyPrintMirOptions, dump_mir_with_options};
 use rustc_middle::mir::{
     Body, ClosureOutlivesSubject, ClosureRegionRequirements, PassWhere, Promoted, create_dump_file,
     dump_enabled, dump_mir,
 };
 use rustc_middle::ty::print::with_no_trimmed_paths;
-use rustc_middle::ty::{self, OpaqueHiddenType, TyCtxt};
+use rustc_middle::ty::{self, TyCtxt};
 use rustc_mir_dataflow::ResultsCursor;
 use rustc_mir_dataflow::impls::MaybeInitializedPlaces;
 use rustc_mir_dataflow::move_paths::MoveData;
@@ -27,6 +25,7 @@ use tracing::{debug, instrument};
 use crate::borrow_set::BorrowSet;
 use crate::consumers::ConsumerOptions;
 use crate::diagnostics::{BorrowckDiagnosticsBuffer, RegionErrors};
+use crate::opaque_types::ConcreteOpaqueTypes;
 use crate::polonius::PoloniusDiagnosticsContext;
 use crate::polonius::legacy::{
     PoloniusFacts, PoloniusFactsExt, PoloniusLocationTable, PoloniusOutput,
@@ -40,7 +39,7 @@ use crate::{BorrowckInferCtxt, polonius, renumber};
 /// closure requirements to propagate, and any generated errors.
 pub(crate) struct NllOutput<'tcx> {
     pub regioncx: RegionInferenceContext<'tcx>,
-    pub opaque_type_values: FxIndexMap<LocalDefId, OpaqueHiddenType<'tcx>>,
+    pub concrete_opaque_types: ConcreteOpaqueTypes<'tcx>,
     pub polonius_input: Option<Box<PoloniusFacts>>,
     pub polonius_output: Option<Box<PoloniusOutput>>,
     pub opt_closure_req: Option<ClosureRegionRequirements<'tcx>>,
@@ -99,6 +98,8 @@ pub(crate) fn compute_regions<'a, 'tcx>(
 
     let location_map = Rc::new(DenseLocationMap::new(body));
 
+    let mut concrete_opaque_types = ConcreteOpaqueTypes::default();
+
     // Run the MIR type-checker.
     let MirTypeckResults {
         constraints,
@@ -116,6 +117,7 @@ pub(crate) fn compute_regions<'a, 'tcx>(
         flow_inits,
         move_data,
         Rc::clone(&location_map),
+        &mut concrete_opaque_types,
     );
 
     // Create the region inference context, taking ownership of the
@@ -180,11 +182,11 @@ pub(crate) fn compute_regions<'a, 'tcx>(
         infcx.set_tainted_by_errors(guar);
     }
 
-    let remapped_opaque_tys = regioncx.infer_opaque_types(infcx, opaque_type_values);
+    regioncx.infer_opaque_types(infcx, opaque_type_values, &mut concrete_opaque_types);
 
     NllOutput {
         regioncx,
-        opaque_type_values: remapped_opaque_tys,
+        concrete_opaque_types,
         polonius_input: polonius_facts.map(Box::new),
         polonius_output,
         opt_closure_req: closure_region_requirements,
@@ -300,7 +302,7 @@ pub(super) fn dump_annotation<'tcx, 'infcx>(
     body: &Body<'tcx>,
     regioncx: &RegionInferenceContext<'tcx>,
     closure_region_requirements: &Option<ClosureRegionRequirements<'tcx>>,
-    opaque_type_values: &FxIndexMap<LocalDefId, OpaqueHiddenType<'tcx>>,
+    concrete_opaque_types: &ConcreteOpaqueTypes<'tcx>,
     diagnostics_buffer: &mut BorrowckDiagnosticsBuffer<'infcx, 'tcx>,
 ) {
     let tcx = infcx.tcx;
@@ -343,8 +345,8 @@ pub(super) fn dump_annotation<'tcx, 'infcx>(
         err
     };
 
-    if !opaque_type_values.is_empty() {
-        err.note(format!("Inferred opaque type values:\n{opaque_type_values:#?}"));
+    if !concrete_opaque_types.is_empty() {
+        err.note(format!("Inferred opaque type values:\n{concrete_opaque_types:#?}"));
     }
 
     diagnostics_buffer.buffer_non_error(err);

compiler/rustc_borrowck/src/opaque_types.rs

@@ -0,0 +1,55 @@
+use rustc_data_structures::fx::FxIndexMap;
+use rustc_hir::def_id::LocalDefId;
+use rustc_middle::ty::{OpaqueHiddenType, Ty, TyCtxt};
+
+#[derive(Debug, Default)]
+pub(super) struct ConcreteOpaqueTypes<'tcx> {
+    concrete_opaque_types: FxIndexMap<LocalDefId, OpaqueHiddenType<'tcx>>,
+}
+
+impl<'tcx> ConcreteOpaqueTypes<'tcx> {
+    pub(super) fn is_empty(&self) -> bool {
+        self.concrete_opaque_types.is_empty()
+    }
+
+    pub(super) fn into_inner(self) -> FxIndexMap<LocalDefId, OpaqueHiddenType<'tcx>> {
+        self.concrete_opaque_types
+    }
+
+    /// Insert an opaque type into the list of opaque types defined by this function
+    /// after mapping the hidden type to the generic parameters of the opaque type
+    /// definition.
+    pub(super) fn insert(
+        &mut self,
+        tcx: TyCtxt<'tcx>,
+        def_id: LocalDefId,
+        hidden_ty: OpaqueHiddenType<'tcx>,
+    ) {
+        // Sometimes two opaque types are the same only after we remap the generic parameters
+        // back to the opaque type definition. E.g. we may have `OpaqueType<X, Y>` mapped to
+        // `(X, Y)` and `OpaqueType<Y, X>` mapped to `(Y, X)`, and those are the same, but we
+        // only know that once we convert the generic parameters to those of the opaque type.
+        if let Some(prev) = self.concrete_opaque_types.get_mut(&def_id) {
+            if prev.ty != hidden_ty.ty {
+                let (Ok(guar) | Err(guar)) =
+                    prev.build_mismatch_error(&hidden_ty, tcx).map(|d| d.emit());
+                prev.ty = Ty::new_error(tcx, guar);
+            }
+            // Pick a better span if there is one.
+            // FIXME(oli-obk): collect multiple spans for better diagnostics down the road.
+            prev.span = prev.span.substitute_dummy(hidden_ty.span);
+        } else {
+            self.concrete_opaque_types.insert(def_id, hidden_ty);
+        }
+    }
+
+    pub(super) fn extend_from_nested_body(
+        &mut self,
+        tcx: TyCtxt<'tcx>,
+        nested_body: &FxIndexMap<LocalDefId, OpaqueHiddenType<'tcx>>,
+    ) {
+        for (&def_id, &hidden_ty) in nested_body {
+            self.insert(tcx, def_id, hidden_ty);
+        }
+    }
+}