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

add `TypingMode::Borrowck`

Still not quite ready

Based on rust-lang#138492

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

Author: bors

compiler/rustc_ast_passes/src/feature_gate.rs

@@ -490,7 +490,6 @@ pub fn check_crate(krate: &ast::Crate, sess: &Session, features: &Features) {
         half_open_range_patterns_in_slices,
         "half-open range patterns in slices are unstable"
     );
-    gate_all!(inline_const_pat, "inline-const in pattern position is experimental");
     gate_all!(associated_const_equality, "associated const equality is incomplete");
     gate_all!(yeet_expr, "`do yeet` expression is experimental");
     gate_all!(dyn_star, "`dyn*` trait objects are experimental");

compiler/rustc_borrowck/messages.ftl

@@ -162,13 +162,6 @@ borrowck_opaque_type_lifetime_mismatch =
     .prev_lifetime_label = lifetime `{$prev}` previously used here
     .note = if all non-lifetime generic parameters are the same, but the lifetime parameters differ, it is not possible to differentiate the opaque types
 
-borrowck_opaque_type_non_generic_param =
-    expected generic {$kind} parameter, found `{$ty}`
-    .label = {STREQ($ty, "'static") ->
-        [true] cannot use static lifetime; use a bound lifetime instead or remove the lifetime parameter from the opaque type
-        *[other] this generic parameter must be used with a generic {$kind} parameter
-    }
-
 borrowck_partial_var_move_by_use_in_closure =
     variable {$is_partial ->
         [true] partially moved

compiler/rustc_borrowck/src/consumers.rs

@@ -1,7 +1,7 @@
 //! This file provides API for compiler consumers.
 
 use rustc_hir::def_id::LocalDefId;
-use rustc_index::{IndexSlice, IndexVec};
+use rustc_index::IndexVec;
 use rustc_middle::mir::{Body, Promoted};
 use rustc_middle::ty::TyCtxt;
 
@@ -100,8 +100,5 @@ pub fn get_body_with_borrowck_facts(
     def: LocalDefId,
     options: ConsumerOptions,
 ) -> BodyWithBorrowckFacts<'_> {
-    let (input_body, promoted) = tcx.mir_promoted(def);
-    let input_body: &Body<'_> = &input_body.borrow();
-    let promoted: &IndexSlice<_, _> = &promoted.borrow();
-    *super::do_mir_borrowck(tcx, input_body, promoted, Some(options)).1.unwrap()
+    *super::do_mir_borrowck(tcx, def, Some(options)).1.unwrap()
 }

compiler/rustc_borrowck/src/lib.rs

@@ -35,7 +35,7 @@ use rustc_infer::infer::{
 };
 use rustc_middle::mir::*;
 use rustc_middle::query::Providers;
-use rustc_middle::ty::{self, ParamEnv, RegionVid, TyCtxt, TypingMode, fold_regions};
+use rustc_middle::ty::{self, ParamEnv, RegionVid, TyCtxt, TypingMode};
 use rustc_middle::{bug, span_bug};
 use rustc_mir_dataflow::impls::{
     EverInitializedPlaces, MaybeInitializedPlaces, MaybeUninitializedPlaces,
@@ -103,11 +103,8 @@ pub fn provide(providers: &mut Providers) {
 }
 
 fn mir_borrowck(tcx: TyCtxt<'_>, def: LocalDefId) -> &BorrowCheckResult<'_> {
-    let (input_body, promoted) = tcx.mir_promoted(def);
-    debug!("run query mir_borrowck: {}", tcx.def_path_str(def));
-
+    let (input_body, _0) = tcx.mir_promoted(def);
     let input_body: &Body<'_> = &input_body.borrow();
-
     if input_body.should_skip() || input_body.tainted_by_errors.is_some() {
         debug!("Skipping borrowck because of injected body or tainted body");
         // Let's make up a borrowck result! Fun times!
@@ -120,7 +117,7 @@ fn mir_borrowck(tcx: TyCtxt<'_>, def: LocalDefId) -> &BorrowCheckResult<'_> {
         return tcx.arena.alloc(result);
     }
 
-    let borrowck_result = do_mir_borrowck(tcx, input_body, &*promoted.borrow(), None).0;
+    let borrowck_result = do_mir_borrowck(tcx, def, None).0;
     debug!("mir_borrowck done");
 
     tcx.arena.alloc(borrowck_result)
@@ -131,15 +128,16 @@ fn mir_borrowck(tcx: TyCtxt<'_>, def: LocalDefId) -> &BorrowCheckResult<'_> {
 /// Use `consumer_options: None` for the default behavior of returning
 /// [`BorrowCheckResult`] only. Otherwise, return [`BodyWithBorrowckFacts`] according
 /// to the given [`ConsumerOptions`].
-#[instrument(skip(tcx, input_body, input_promoted), fields(id=?input_body.source.def_id()), level = "debug")]
+#[instrument(skip(tcx), level = "debug")]
 fn do_mir_borrowck<'tcx>(
     tcx: TyCtxt<'tcx>,
-    input_body: &Body<'tcx>,
-    input_promoted: &IndexSlice<Promoted, Body<'tcx>>,
+    def: LocalDefId,
     consumer_options: Option<ConsumerOptions>,
 ) -> (BorrowCheckResult<'tcx>, Option<Box<BodyWithBorrowckFacts<'tcx>>>) {
-    let def = input_body.source.def_id().expect_local();
     let infcx = BorrowckInferCtxt::new(tcx, def);
+    let (input_body, promoted) = tcx.mir_promoted(def);
+    let input_body: &Body<'_> = &input_body.borrow();
+    let input_promoted: &IndexSlice<_, _> = &promoted.borrow();
     if let Some(e) = input_body.tainted_by_errors {
         infcx.set_tainted_by_errors(e);
     }
@@ -173,12 +171,6 @@ fn do_mir_borrowck<'tcx>(
     let free_regions = nll::replace_regions_in_mir(&infcx, &mut body_owned, &mut promoted);
     let body = &body_owned; // no further changes
 
-    // FIXME(-Znext-solver): A bit dubious that we're only registering
-    // predefined opaques in the typeck root.
-    if infcx.next_trait_solver() && !infcx.tcx.is_typeck_child(body.source.def_id()) {
-        infcx.register_predefined_opaques_for_next_solver(def);
-    }
-
     let location_table = PoloniusLocationTable::new(body);
 
     let move_data = MoveData::gather_moves(body, tcx, |_| true);
@@ -433,7 +425,12 @@ pub(crate) struct BorrowckInferCtxt<'tcx> {
 
 impl<'tcx> BorrowckInferCtxt<'tcx> {
     pub(crate) fn new(tcx: TyCtxt<'tcx>, def_id: LocalDefId) -> Self {
-        let infcx = tcx.infer_ctxt().build(TypingMode::analysis_in_body(tcx, def_id));
+        let typing_mode = if tcx.use_typing_mode_borrowck() {
+            TypingMode::borrowck(tcx, def_id)
+        } else {
+            TypingMode::analysis_in_body(tcx, def_id)
+        };
+        let infcx = tcx.infer_ctxt().build(typing_mode);
         let param_env = tcx.param_env(def_id);
         BorrowckInferCtxt { infcx, reg_var_to_origin: RefCell::new(Default::default()), param_env }
     }
@@ -480,28 +477,6 @@ impl<'tcx> BorrowckInferCtxt<'tcx> {
 
         next_region
     }
-
-    /// With the new solver we prepopulate the opaque type storage during
-    /// MIR borrowck with the hidden types from HIR typeck. This is necessary
-    /// to avoid ambiguities as earlier goals can rely on the hidden type
-    /// of an opaque which is only constrained by a later goal.
-    fn register_predefined_opaques_for_next_solver(&self, def_id: LocalDefId) {
-        let tcx = self.tcx;
-        // OK to use the identity arguments for each opaque type key, since
-        // we remap opaques from HIR typeck back to their definition params.
-        for data in tcx.typeck(def_id).concrete_opaque_types.iter().map(|(k, v)| (*k, *v)) {
-            // HIR typeck did not infer the regions of the opaque, so we instantiate
-            // them with fresh inference variables.
-            let (key, hidden_ty) = fold_regions(tcx, data, |_, _| {
-                self.next_nll_region_var_in_universe(
-                    NllRegionVariableOrigin::Existential { from_forall: false },
-                    ty::UniverseIndex::ROOT,
-                )
-            });
-
-            self.inject_new_hidden_type_unchecked(key, hidden_ty);
-        }
-    }
 }
 
 impl<'tcx> Deref for BorrowckInferCtxt<'tcx> {

compiler/rustc_borrowck/src/region_infer/opaque_types.rs

@@ -1,22 +1,17 @@
 use rustc_data_structures::fx::FxIndexMap;
-use rustc_errors::ErrorGuaranteed;
-use rustc_hir::OpaqueTyOrigin;
-use rustc_hir::def_id::LocalDefId;
-use rustc_infer::infer::outlives::env::OutlivesEnvironment;
-use rustc_infer::infer::{InferCtxt, NllRegionVariableOrigin, TyCtxtInferExt as _};
+use rustc_infer::infer::{InferCtxt, NllRegionVariableOrigin};
 use rustc_macros::extension;
 use rustc_middle::ty::{
-    self, GenericArgKind, GenericArgs, OpaqueHiddenType, OpaqueTypeKey, Ty, TyCtxt, TypeFoldable,
-    TypeVisitableExt, TypingMode, fold_regions,
+    self, DefiningScopeKind, OpaqueHiddenType, OpaqueTypeKey, Ty, TyCtxt, TypeFoldable,
+    TypeVisitableExt, fold_regions,
 };
 use rustc_span::Span;
-use rustc_trait_selection::regions::OutlivesEnvironmentBuildExt;
-use rustc_trait_selection::traits::ObligationCtxt;
+use rustc_trait_selection::opaque_types::check_opaque_type_parameter_valid;
 use tracing::{debug, instrument};
 
 use super::RegionInferenceContext;
 use crate::opaque_types::ConcreteOpaqueTypes;
-use crate::session_diagnostics::{LifetimeMismatchOpaqueParam, NonGenericOpaqueTypeParam};
+use crate::session_diagnostics::LifetimeMismatchOpaqueParam;
 use crate::universal_regions::RegionClassification;
 
 impl<'tcx> RegionInferenceContext<'tcx> {
@@ -272,14 +267,21 @@ impl<'tcx> InferCtxt<'tcx> {
             return Ty::new_error(self.tcx, e);
         }
 
-        if let Err(guar) =
-            check_opaque_type_parameter_valid(self, opaque_type_key, instantiated_ty.span)
-        {
+        if let Err(guar) = check_opaque_type_parameter_valid(
+            self,
+            opaque_type_key,
+            instantiated_ty.span,
+            DefiningScopeKind::MirBorrowck,
+        ) {
             return Ty::new_error(self.tcx, guar);
         }
 
         let definition_ty = instantiated_ty
-            .remap_generic_params_to_declaration_params(opaque_type_key, self.tcx, false)
+            .remap_generic_params_to_declaration_params(
+                opaque_type_key,
+                self.tcx,
+                DefiningScopeKind::MirBorrowck,
+            )
             .ty;
 
         if let Err(e) = definition_ty.error_reported() {
@@ -289,156 +291,3 @@ impl<'tcx> InferCtxt<'tcx> {
         definition_ty
     }
 }
-
-/// Opaque type parameter validity check as documented in the [rustc-dev-guide chapter].
-///
-/// [rustc-dev-guide chapter]:
-/// https://rustc-dev-guide.rust-lang.org/opaque-types-region-infer-restrictions.html
-fn check_opaque_type_parameter_valid<'tcx>(
-    infcx: &InferCtxt<'tcx>,
-    opaque_type_key: OpaqueTypeKey<'tcx>,
-    span: Span,
-) -> Result<(), ErrorGuaranteed> {
-    let tcx = infcx.tcx;
-    let opaque_generics = tcx.generics_of(opaque_type_key.def_id);
-    let opaque_env = LazyOpaqueTyEnv::new(tcx, opaque_type_key.def_id);
-    let mut seen_params: FxIndexMap<_, Vec<_>> = FxIndexMap::default();
-
-    for (i, arg) in opaque_type_key.iter_captured_args(tcx) {
-        let arg_is_param = match arg.unpack() {
-            GenericArgKind::Type(ty) => matches!(ty.kind(), ty::Param(_)),
-            GenericArgKind::Lifetime(lt) => {
-                matches!(*lt, ty::ReEarlyParam(_) | ty::ReLateParam(_))
-                    || (lt.is_static() && opaque_env.param_equal_static(i))
-            }
-            GenericArgKind::Const(ct) => matches!(ct.kind(), ty::ConstKind::Param(_)),
-        };
-
-        if arg_is_param {
-            // Register if the same lifetime appears multiple times in the generic args.
-            // There is an exception when the opaque type *requires* the lifetimes to be equal.
-            // See [rustc-dev-guide chapter] § "An exception to uniqueness rule".
-            let seen_where = seen_params.entry(arg).or_default();
-            if !seen_where.first().is_some_and(|&prev_i| opaque_env.params_equal(i, prev_i)) {
-                seen_where.push(i);
-            }
-        } else {
-            // Prevent `fn foo() -> Foo<u32>` from being defining.
-            let opaque_param = opaque_generics.param_at(i, tcx);
-            let kind = opaque_param.kind.descr();
-
-            opaque_env.param_is_error(i)?;
-
-            return Err(infcx.dcx().emit_err(NonGenericOpaqueTypeParam {
-                ty: arg,
-                kind,
-                span,
-                param_span: tcx.def_span(opaque_param.def_id),
-            }));
-        }
-    }
-
-    for (_, indices) in seen_params {
-        if indices.len() > 1 {
-            let descr = opaque_generics.param_at(indices[0], tcx).kind.descr();
-            let spans: Vec<_> = indices
-                .into_iter()
-                .map(|i| tcx.def_span(opaque_generics.param_at(i, tcx).def_id))
-                .collect();
-            #[allow(rustc::diagnostic_outside_of_impl)]
-            #[allow(rustc::untranslatable_diagnostic)]
-            return Err(infcx
-                .dcx()
-                .struct_span_err(span, "non-defining opaque type use in defining scope")
-                .with_span_note(spans, format!("{descr} used multiple times"))
-                .emit());
-        }
-    }
-
-    Ok(())
-}
-
-/// Computes if an opaque type requires a lifetime parameter to be equal to
-/// another one or to the `'static` lifetime.
-/// These requirements are derived from the explicit and implied bounds.
-struct LazyOpaqueTyEnv<'tcx> {
-    tcx: TyCtxt<'tcx>,
-    def_id: LocalDefId,
-
-    /// Equal parameters will have the same name. Computed Lazily.
-    /// Example:
-    ///     `type Opaque<'a: 'static, 'b: 'c, 'c: 'b> = impl Sized;`
-    ///     Identity args: `['a, 'b, 'c]`
-    ///     Canonical args: `['static, 'b, 'b]`
-    canonical_args: std::cell::OnceCell<ty::GenericArgsRef<'tcx>>,
-}
-
-impl<'tcx> LazyOpaqueTyEnv<'tcx> {
-    fn new(tcx: TyCtxt<'tcx>, def_id: LocalDefId) -> Self {
-        Self { tcx, def_id, canonical_args: std::cell::OnceCell::new() }
-    }
-
-    fn param_equal_static(&self, param_index: usize) -> bool {
-        self.get_canonical_args()[param_index].expect_region().is_static()
-    }
-
-    fn params_equal(&self, param1: usize, param2: usize) -> bool {
-        let canonical_args = self.get_canonical_args();
-        canonical_args[param1] == canonical_args[param2]
-    }
-
-    fn param_is_error(&self, param_index: usize) -> Result<(), ErrorGuaranteed> {
-        self.get_canonical_args()[param_index].error_reported()
-    }
-
-    fn get_canonical_args(&self) -> ty::GenericArgsRef<'tcx> {
-        if let Some(&canonical_args) = self.canonical_args.get() {
-            return canonical_args;
-        }
-
-        let &Self { tcx, def_id, .. } = self;
-        let origin = tcx.local_opaque_ty_origin(def_id);
-        let parent = match origin {
-            OpaqueTyOrigin::FnReturn { parent, .. }
-            | OpaqueTyOrigin::AsyncFn { parent, .. }
-            | OpaqueTyOrigin::TyAlias { parent, .. } => parent,
-        };
-        let param_env = tcx.param_env(parent);
-        let args = GenericArgs::identity_for_item(tcx, parent).extend_to(
-            tcx,
-            def_id.to_def_id(),
-            |param, _| {
-                tcx.map_opaque_lifetime_to_parent_lifetime(param.def_id.expect_local()).into()
-            },
-        );
-
-        // FIXME(#132279): It feels wrong to use `non_body_analysis` here given that we're
-        // in a body here.
-        let infcx = tcx.infer_ctxt().build(TypingMode::non_body_analysis());
-        let ocx = ObligationCtxt::new(&infcx);
-
-        let wf_tys = ocx.assumed_wf_types(param_env, parent).unwrap_or_else(|_| {
-            tcx.dcx().span_delayed_bug(tcx.def_span(def_id), "error getting implied bounds");
-            Default::default()
-        });
-        let outlives_env = OutlivesEnvironment::new(&infcx, parent, param_env, wf_tys);
-
-        let mut seen = vec![tcx.lifetimes.re_static];
-        let canonical_args = fold_regions(tcx, args, |r1, _| {
-            if r1.is_error() {
-                r1
-            } else if let Some(&r2) = seen.iter().find(|&&r2| {
-                let free_regions = outlives_env.free_region_map();
-                free_regions.sub_free_regions(tcx, r1, r2)
-                    && free_regions.sub_free_regions(tcx, r2, r1)
-            }) {
-                r2
-            } else {
-                seen.push(r1);
-                r1
-            }
-        });
-        self.canonical_args.set(canonical_args).unwrap();
-        canonical_args
-    }
-}