Auto merge of rust-lang#118141 - matthiaskrgr:rollup-djkmfwt, r=matth…

…iaskrgr

Rollup of 4 pull requests

Successful merges:

 - rust-lang#117972 (Add VarDebugInfo to Stable MIR)
 - rust-lang#118110 (Document `DefiningAnchor` a bit more)
 - rust-lang#118112 (Don't ICE when ambiguity is found when selecting `Index` implementation in typeck)
 - rust-lang#118135 (Remove quotation from filename in stable_mir)

Failed merges:

 - rust-lang#118012 (Add support for global allocation in smir)

r? `@ghost`
`@rustbot` modify labels: rollup

compiler/rustc_hir_typeck/src/expr.rs

@@ -3067,7 +3067,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             return None;
         };
 
-        self.commit_if_ok(|_| {
+        self.commit_if_ok(|snapshot| {
+            let outer_universe = self.universe();
+
             let ocx = ObligationCtxt::new(self);
             let impl_args = self.fresh_args_for_item(base_expr.span, impl_def_id);
             let impl_trait_ref =
@@ -3077,7 +3079,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             // Match the impl self type against the base ty. If this fails,
             // we just skip this impl, since it's not particularly useful.
             let impl_trait_ref = ocx.normalize(&cause, self.param_env, impl_trait_ref);
-            ocx.eq(&cause, self.param_env, impl_trait_ref.self_ty(), base_ty)?;
+            ocx.eq(&cause, self.param_env, base_ty, impl_trait_ref.self_ty())?;
 
             // Register the impl's predicates. One of these predicates
             // must be unsatisfied, or else we wouldn't have gotten here
@@ -3113,11 +3115,23 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 Ty::new_projection(self.tcx, index_trait_output_def_id, impl_trait_ref.args),
             );
 
-            let errors = ocx.select_where_possible();
+            let true_errors = ocx.select_where_possible();
+
+            // Do a leak check -- we can't really report report a useful error here,
+            // but it at least avoids an ICE when the error has to do with higher-ranked
+            // lifetimes.
+            self.leak_check(outer_universe, Some(snapshot))?;
+
+            // Bail if we have ambiguity errors, which we can't report in a useful way.
+            let ambiguity_errors = ocx.select_all_or_error();
+            if true_errors.is_empty() && !ambiguity_errors.is_empty() {
+                return Err(NoSolution);
+            }
+
             // There should be at least one error reported. If not, we
             // will still delay a span bug in `report_fulfillment_errors`.
             Ok::<_, NoSolution>((
-                self.err_ctxt().report_fulfillment_errors(errors),
+                self.err_ctxt().report_fulfillment_errors(true_errors),
                 impl_trait_ref.args.type_at(1),
                 element_ty,
             ))

compiler/rustc_middle/src/traits/mod.rs

@@ -956,13 +956,26 @@ pub enum CodegenObligationError {
     FulfillmentError,
 }
 
+/// Defines the treatment of opaque types in a given inference context.
+///
+/// This affects both what opaques are allowed to be defined, but also whether
+/// opaques are replaced with inference vars eagerly in the old solver (e.g.
+/// in projection, and in the signature during function type-checking).
 #[derive(Debug, PartialEq, Eq, Clone, Copy, Hash, HashStable, TypeFoldable, TypeVisitable)]
 pub enum DefiningAnchor {
-    /// `DefId` of the item.
+    /// Define opaques which are in-scope of the `LocalDefId`. Also, eagerly
+    /// replace opaque types in `replace_opaque_types_with_inference_vars`.
     Bind(LocalDefId),
-    /// When opaque types are not resolved, we `Bubble` up, meaning
-    /// return the opaque/hidden type pair from query, for caller of query to handle it.
+    /// In contexts where we don't currently know what opaques are allowed to be
+    /// defined, such as (old solver) canonical queries, we will simply allow
+    /// opaques to be defined, but "bubble" them up in the canonical response or
+    /// otherwise treat them to be handled later.
+    ///
+    /// We do not eagerly replace opaque types in `replace_opaque_types_with_inference_vars`,
+    /// which may affect what predicates pass and fail in the old trait solver.
     Bubble,
-    /// Used to catch type mismatch errors when handling opaque types.
+    /// Do not allow any opaques to be defined. This is used to catch type mismatch
+    /// errors when handling opaque types, and also should be used when we would
+    /// otherwise reveal opaques (such as [`Reveal::All`] reveal mode).
     Error,
 }

compiler/rustc_smir/src/rustc_smir/mod.rs

@@ -18,7 +18,10 @@ use rustc_middle::ty::{self, Instance, ParamEnv, ScalarInt, Ty, TyCtxt, Variance
 use rustc_span::def_id::{CrateNum, DefId, LOCAL_CRATE};
 use rustc_target::abi::FieldIdx;
 use stable_mir::mir::mono::InstanceDef;
-use stable_mir::mir::{Body, CopyNonOverlapping, Statement, UserTypeProjection, VariantIdx};
+use stable_mir::mir::{
+    Body, ConstOperand, CopyNonOverlapping, Statement, UserTypeProjection, VarDebugInfoFragment,
+    VariantIdx,
+};
 use stable_mir::ty::{
     AdtDef, AdtKind, ClosureDef, ClosureKind, Const, ConstId, ConstantKind, EarlyParamRegion,
     FloatTy, FnDef, GenericArgs, GenericParamDef, IntTy, LineInfo, Movability, RigidTy, Span,
@@ -69,15 +72,13 @@ impl<'tcx> Context for TablesWrapper<'tcx> {
 
     fn get_filename(&self, span: &Span) -> Filename {
         let tables = self.0.borrow();
-        opaque(
-            &tables
-                .tcx
-                .sess
-                .source_map()
-                .span_to_filename(tables[*span])
-                .display(rustc_span::FileNameDisplayPreference::Local)
-                .to_string(),
-        )
+        tables
+            .tcx
+            .sess
+            .source_map()
+            .span_to_filename(tables[*span])
+            .display(rustc_span::FileNameDisplayPreference::Local)
+            .to_string()
     }
 
     fn get_lines(&self, span: &Span) -> LineInfo {
@@ -444,17 +445,67 @@ impl<'tcx> Stable<'tcx> for mir::Body<'tcx> {
                 })
                 .collect(),
             self.arg_count,
+            self.var_debug_info.iter().map(|info| info.stable(tables)).collect(),
         )
     }
 }
 
+impl<'tcx> Stable<'tcx> for mir::VarDebugInfo<'tcx> {
+    type T = stable_mir::mir::VarDebugInfo;
+    fn stable(&self, tables: &mut Tables<'tcx>) -> Self::T {
+        stable_mir::mir::VarDebugInfo {
+            name: self.name.to_string(),
+            source_info: self.source_info.stable(tables),
+            composite: self.composite.as_ref().map(|composite| composite.stable(tables)),
+            value: self.value.stable(tables),
+            argument_index: self.argument_index,
+        }
+    }
+}
+
 impl<'tcx> Stable<'tcx> for mir::Statement<'tcx> {
     type T = stable_mir::mir::Statement;
     fn stable(&self, tables: &mut Tables<'tcx>) -> Self::T {
         Statement { kind: self.kind.stable(tables), span: self.source_info.span.stable(tables) }
     }
 }
 
+impl<'tcx> Stable<'tcx> for mir::SourceInfo {
+    type T = stable_mir::mir::SourceInfo;
+    fn stable(&self, tables: &mut Tables<'tcx>) -> Self::T {
+        stable_mir::mir::SourceInfo { span: self.span.stable(tables), scope: self.scope.into() }
+    }
+}
+
+impl<'tcx> Stable<'tcx> for mir::VarDebugInfoFragment<'tcx> {
+    type T = stable_mir::mir::VarDebugInfoFragment;
+    fn stable(&self, tables: &mut Tables<'tcx>) -> Self::T {
+        VarDebugInfoFragment {
+            ty: self.ty.stable(tables),
+            projection: self.projection.iter().map(|e| e.stable(tables)).collect(),
+        }
+    }
+}
+
+impl<'tcx> Stable<'tcx> for mir::VarDebugInfoContents<'tcx> {
+    type T = stable_mir::mir::VarDebugInfoContents;
+    fn stable(&self, tables: &mut Tables<'tcx>) -> Self::T {
+        match self {
+            mir::VarDebugInfoContents::Place(place) => {
+                stable_mir::mir::VarDebugInfoContents::Place(place.stable(tables))
+            }
+            mir::VarDebugInfoContents::Const(const_operand) => {
+                let op = ConstOperand {
+                    span: const_operand.span.stable(tables),
+                    user_ty: const_operand.user_ty.map(|index| index.as_usize()),
+                    const_: const_operand.const_.stable(tables),
+                };
+                stable_mir::mir::VarDebugInfoContents::Const(op)
+            }
+        }
+    }
+}
+
 impl<'tcx> Stable<'tcx> for mir::StatementKind<'tcx> {
     type T = stable_mir::mir::StatementKind;
     fn stable(&self, tables: &mut Tables<'tcx>) -> Self::T {

compiler/stable_mir/src/lib.rs

@@ -110,7 +110,7 @@ pub enum ItemKind {
     Const,
 }
 
-pub type Filename = Opaque;
+pub type Filename = String;
 
 /// Holds information about an item in the crate.
 #[derive(Copy, Clone, PartialEq, Eq, Debug)]

compiler/stable_mir/src/mir/body.rs

@@ -2,7 +2,7 @@ use crate::mir::pretty::{function_body, pretty_statement};
 use crate::ty::{
     AdtDef, ClosureDef, Const, CoroutineDef, GenericArgs, Movability, Region, RigidTy, Ty, TyKind,
 };
-use crate::{Error, Opaque, Span};
+use crate::{Error, Opaque, Span, Symbol};
 use std::io;
 
 /// The SMIR representation of a single function.
@@ -19,21 +19,29 @@ pub struct Body {
 
     // The number of arguments this function takes.
     pub(super) arg_count: usize,
+
+    // Debug information pertaining to user variables, including captures.
+    pub(super) var_debug_info: Vec<VarDebugInfo>,
 }
 
 impl Body {
     /// Constructs a `Body`.
     ///
     /// A constructor is required to build a `Body` from outside the crate
     /// because the `arg_count` and `locals` fields are private.
-    pub fn new(blocks: Vec<BasicBlock>, locals: LocalDecls, arg_count: usize) -> Self {
+    pub fn new(
+        blocks: Vec<BasicBlock>,
+        locals: LocalDecls,
+        arg_count: usize,
+        var_debug_info: Vec<VarDebugInfo>,
+    ) -> Self {
         // If locals doesn't contain enough entries, it can lead to panics in
         // `ret_local`, `arg_locals`, and `inner_locals`.
         assert!(
             locals.len() > arg_count,
             "A Body must contain at least a local for the return value and each of the function's arguments"
         );
-        Self { blocks, locals, arg_count }
+        Self { blocks, locals, arg_count, var_debug_info }
     }
 
     /// Return local that holds this function's return value.
@@ -427,6 +435,42 @@ pub struct Place {
     pub projection: Vec<ProjectionElem>,
 }
 
+#[derive(Clone, Debug, Eq, PartialEq)]
+pub struct VarDebugInfo {
+    pub name: Symbol,
+    pub source_info: SourceInfo,
+    pub composite: Option<VarDebugInfoFragment>,
+    pub value: VarDebugInfoContents,
+    pub argument_index: Option<u16>,
+}
+
+pub type SourceScope = u32;
+
+#[derive(Clone, Debug, Eq, PartialEq)]
+pub struct SourceInfo {
+    pub span: Span,
+    pub scope: SourceScope,
+}
+
+#[derive(Clone, Debug, Eq, PartialEq)]
+pub struct VarDebugInfoFragment {
+    pub ty: Ty,
+    pub projection: Vec<ProjectionElem>,
+}
+
+#[derive(Clone, Debug, Eq, PartialEq)]
+pub enum VarDebugInfoContents {
+    Place(Place),
+    Const(ConstOperand),
+}
+
+#[derive(Clone, Debug, Eq, PartialEq)]
+pub struct ConstOperand {
+    pub span: Span,
+    pub user_ty: Option<UserTypeAnnotationIndex>,
+    pub const_: Const,
+}
+
 // In MIR ProjectionElem is parameterized on the second Field argument and the Index argument. This
 // is so it can be used for both Places (for which the projection elements are of type
 // ProjectionElem<Local, Ty>) and user-provided type annotations (for which the projection elements

compiler/stable_mir/src/mir/visit.rs

@@ -128,8 +128,12 @@ pub trait MirVisitor {
         self.super_assert_msg(msg, location)
     }
 
+    fn visit_var_debug_info(&mut self, var_debug_info: &VarDebugInfo) {
+        self.super_var_debug_info(var_debug_info);
+    }
+
     fn super_body(&mut self, body: &Body) {
-        let Body { blocks, locals: _, arg_count } = body;
+        let Body { blocks, locals: _, arg_count, var_debug_info } = body;
 
         for bb in blocks {
             self.visit_basic_block(bb);
@@ -145,6 +149,10 @@ pub trait MirVisitor {
         for (idx, arg) in body.inner_locals().iter().enumerate() {
             self.visit_local_decl(idx + local_start, arg)
         }
+
+        for info in var_debug_info.iter() {
+            self.visit_var_debug_info(info);
+        }
     }
 
     fn super_basic_block(&mut self, bb: &BasicBlock) {
@@ -382,6 +390,24 @@ pub trait MirVisitor {
         let _ = args;
     }
 
+    fn super_var_debug_info(&mut self, var_debug_info: &VarDebugInfo) {
+        let VarDebugInfo { source_info, composite, value, name: _, argument_index: _ } =
+            var_debug_info;
+        self.visit_span(&source_info.span);
+        let location = Location(source_info.span);
+        if let Some(composite) = composite {
+            self.visit_ty(&composite.ty, location);
+        }
+        match value {
+            VarDebugInfoContents::Place(place) => {
+                self.visit_place(place, PlaceContext::NON_USE, location);
+            }
+            VarDebugInfoContents::Const(constant) => {
+                self.visit_const(&constant.const_, location);
+            }
+        }
+    }
+
     fn super_assert_msg(&mut self, msg: &AssertMessage, location: Location) {
         match msg {
             AssertMessage::BoundsCheck { len, index } => {

tests/ui/typeck/bad-index-modulo-higher-ranked-regions.rs

@@ -0,0 +1,29 @@
+// Test against ICE in #118111
+
+use std::ops::Index;
+
+struct Map<T, F> {
+    f: F,
+    inner: T,
+}
+
+impl<T, F, Idx> Index<Idx> for Map<T, F>
+where
+    T: Index<Idx>,
+    F: FnOnce(&T, Idx) -> Idx,
+{
+    type Output = T::Output;
+
+    fn index(&self, index: Idx) -> &Self::Output {
+        todo!()
+    }
+}
+
+fn main() {
+    Map { inner: [0_usize], f: |_, i: usize| 1_usize }[0];
+    //~^ ERROR cannot index into a value of type
+    // Problem here is that
+    //   `f: |_, i: usize| ...`
+    // should be
+    //   `f: |_: &_, i: usize| ...`
+}

tests/ui/typeck/bad-index-modulo-higher-ranked-regions.stderr

@@ -0,0 +1,9 @@
+error[E0608]: cannot index into a value of type `Map<[usize; 1], {closure@$DIR/bad-index-modulo-higher-ranked-regions.rs:23:32: 23:45}>`
+  --> $DIR/bad-index-modulo-higher-ranked-regions.rs:23:55
+   |
+LL |     Map { inner: [0_usize], f: |_, i: usize| 1_usize }[0];
+   |                                                       ^^^
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0608`.