Merge branch 'master' of https://github.com/amg98/rust

Author: AMG

Cargo.lock

@@ -710,9 +710,9 @@ dependencies = [
 
 [[package]]
 name = "compiletest_rs"
-version = "0.7.0"
+version = "0.7.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "64698e5e2435db061a85e6320af12c30c5fd88eb84b35d2c1e03ce4f143255ca"
+checksum = "29843cb8d351febf86557681d049d1e1652b81a086a190fa1173c07fd17fbf83"
 dependencies = [
  "diff",
  "filetime",
@@ -1900,9 +1900,9 @@ checksum = "830d08ce1d1d941e6b30645f1a0eb5643013d835ce3779a5fc208261dbe10f55"
 
 [[package]]
 name = "libc"
-version = "0.2.103"
+version = "0.2.106"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "dd8f7255a17a627354f321ef0055d63b898c6fb27eff628af4d1b66b7331edf6"
+checksum = "a60553f9a9e039a333b4e9b20573b9e9b9c0bb3a11e201ccc48ef4283456d673"
 dependencies = [
  "rustc-std-workspace-core",
 ]

compiler/rustc_ast/README.md

@@ -1,6 +1,5 @@
 The `rustc_ast` crate contains those things concerned purely with syntax
-– that is, the AST ("abstract syntax tree"), parser, pretty-printer,
-lexer, macro expander, and utilities for traversing ASTs.
+– that is, the AST ("abstract syntax tree"), along with some definitions for tokens and token streams, data structures/traits for mutating ASTs, and shared definitions for other AST-related parts of the compiler (like the lexer and macro-expansion).
 
 For more information about how these things work in rustc, see the
 rustc dev guide:

compiler/rustc_ast/src/lib.rs

@@ -1,4 +1,4 @@
-//! The Rust parser and macro expander.
+//! The Rust Abstract Syntax Tree (AST).
 //!
 //! # Note
 //!

compiler/rustc_const_eval/src/transform/check_consts/resolver.rs

@@ -94,11 +94,10 @@ where
         }
     }
 
-    fn address_of_allows_mutation(&self, mt: mir::Mutability, place: mir::Place<'tcx>) -> bool {
-        match mt {
-            mir::Mutability::Mut => true,
-            mir::Mutability::Not => self.shared_borrow_allows_mutation(place),
-        }
+    fn address_of_allows_mutation(&self, _mt: mir::Mutability, _place: mir::Place<'tcx>) -> bool {
+        // Exact set of permissions granted by AddressOf is undecided. Conservatively assume that
+        // it might allow mutation until resolution of #56604.
+        true
     }
 
     fn ref_allows_mutation(&self, kind: mir::BorrowKind, place: mir::Place<'tcx>) -> bool {
@@ -110,6 +109,15 @@ where
         }
     }
 
+    /// `&` only allow mutation if the borrowed place is `!Freeze`.
+    ///
+    /// This assumes that it is UB to take the address of a struct field whose type is
+    /// `Freeze`, then use pointer arithmetic to derive a pointer to a *different* field of
+    /// that same struct whose type is `!Freeze`. If we decide that this is not UB, we will
+    /// have to check the type of the borrowed **local** instead of the borrowed **place**
+    /// below. See [rust-lang/unsafe-code-guidelines#134].
+    ///
+    /// [rust-lang/unsafe-code-guidelines#134]: https://github.com/rust-lang/unsafe-code-guidelines/issues/134
     fn shared_borrow_allows_mutation(&self, place: mir::Place<'tcx>) -> bool {
         !place
             .ty(self.ccx.body, self.ccx.tcx)

compiler/rustc_infer/src/infer/error_reporting/nice_region_error/different_lifetimes.rs

@@ -7,7 +7,10 @@ use crate::infer::error_reporting::nice_region_error::NiceRegionError;
 use crate::infer::lexical_region_resolve::RegionResolutionError;
 use crate::infer::SubregionOrigin;
 
-use rustc_errors::{struct_span_err, ErrorReported};
+use rustc_errors::{struct_span_err, Applicability, DiagnosticBuilder, ErrorReported};
+use rustc_hir as hir;
+use rustc_hir::{GenericParamKind, Ty};
+use rustc_middle::ty::Region;
 
 impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
     /// Print the error message for lifetime errors when both the concerned regions are anonymous.
@@ -160,11 +163,13 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
                 }
             };
 
-        let mut e = struct_span_err!(self.tcx().sess, span, E0623, "lifetime mismatch");
+        let mut err = struct_span_err!(self.tcx().sess, span, E0623, "lifetime mismatch");
 
-        e.span_label(span_1, main_label);
-        e.span_label(span_2, String::new());
-        e.span_label(span, span_label);
+        err.span_label(span_1, main_label);
+        err.span_label(span_2, String::new());
+        err.span_label(span, span_label);
+
+        self.suggest_adding_lifetime_params(sub, ty_sup, ty_sub, &mut err);
 
         if let Some(t) = future_return_type {
             let snip = self
@@ -178,14 +183,87 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
                     (_, "") => None,
                     _ => Some(s),
                 })
-                .unwrap_or("{unnamed_type}".to_string());
+                .unwrap_or_else(|| "{unnamed_type}".to_string());
 
-            e.span_label(
+            err.span_label(
                 t.span,
                 &format!("this `async fn` implicitly returns an `impl Future<Output = {}>`", snip),
             );
         }
-        e.emit();
+        err.emit();
         Some(ErrorReported)
     }
+
+    fn suggest_adding_lifetime_params(
+        &self,
+        sub: Region<'tcx>,
+        ty_sup: &Ty<'_>,
+        ty_sub: &Ty<'_>,
+        err: &mut DiagnosticBuilder<'_>,
+    ) {
+        if let (
+            hir::Ty { kind: hir::TyKind::Rptr(lifetime_sub, _), .. },
+            hir::Ty { kind: hir::TyKind::Rptr(lifetime_sup, _), .. },
+        ) = (ty_sub, ty_sup)
+        {
+            if lifetime_sub.name.is_elided() && lifetime_sup.name.is_elided() {
+                if let Some(anon_reg) = self.tcx().is_suitable_region(sub) {
+                    let hir_id = self.tcx().hir().local_def_id_to_hir_id(anon_reg.def_id);
+                    if let hir::Node::Item(&hir::Item {
+                        kind: hir::ItemKind::Fn(_, ref generics, ..),
+                        ..
+                    }) = self.tcx().hir().get(hir_id)
+                    {
+                        let (suggestion_param_name, introduce_new) = generics
+                            .params
+                            .iter()
+                            .find(|p| matches!(p.kind, GenericParamKind::Lifetime { .. }))
+                            .and_then(|p| self.tcx().sess.source_map().span_to_snippet(p.span).ok())
+                            .map(|name| (name, false))
+                            .unwrap_or_else(|| ("'a".to_string(), true));
+
+                        let mut suggestions = vec![
+                            if let hir::LifetimeName::Underscore = lifetime_sub.name {
+                                (lifetime_sub.span, suggestion_param_name.clone())
+                            } else {
+                                (
+                                    lifetime_sub.span.shrink_to_hi(),
+                                    suggestion_param_name.clone() + " ",
+                                )
+                            },
+                            if let hir::LifetimeName::Underscore = lifetime_sup.name {
+                                (lifetime_sup.span, suggestion_param_name.clone())
+                            } else {
+                                (
+                                    lifetime_sup.span.shrink_to_hi(),
+                                    suggestion_param_name.clone() + " ",
+                                )
+                            },
+                        ];
+
+                        if introduce_new {
+                            let new_param_suggestion = match &generics.params {
+                                [] => (generics.span, format!("<{}>", suggestion_param_name)),
+                                [first, ..] => (
+                                    first.span.shrink_to_lo(),
+                                    format!("{}, ", suggestion_param_name),
+                                ),
+                            };
+
+                            suggestions.push(new_param_suggestion);
+                        }
+
+                        err.multipart_suggestion(
+                            "consider introducing a named lifetime parameter",
+                            suggestions,
+                            Applicability::MaybeIncorrect,
+                        );
+                        err.note(
+                            "each elided lifetime in input position becomes a distinct lifetime",
+                        );
+                    }
+                }
+            }
+        }
+    }
 }

compiler/rustc_mir_dataflow/src/impls/borrowed_locals.rs

@@ -3,55 +3,26 @@ use super::*;
 use crate::{AnalysisDomain, GenKill, GenKillAnalysis};
 use rustc_middle::mir::visit::Visitor;
 use rustc_middle::mir::*;
-use rustc_middle::ty::{ParamEnv, TyCtxt};
-use rustc_span::DUMMY_SP;
-
-pub type MaybeMutBorrowedLocals<'mir, 'tcx> = MaybeBorrowedLocals<MutBorrow<'mir, 'tcx>>;
 
 /// A dataflow analysis that tracks whether a pointer or reference could possibly exist that points
 /// to a given local.
 ///
-/// The `K` parameter determines what kind of borrows are tracked. By default,
-/// `MaybeBorrowedLocals` looks for *any* borrow of a local. If you are only interested in borrows
-/// that might allow mutation, use the `MaybeMutBorrowedLocals` type alias instead.
-///
 /// At present, this is used as a very limited form of alias analysis. For example,
 /// `MaybeBorrowedLocals` is used to compute which locals are live during a yield expression for
-/// immovable generators. `MaybeMutBorrowedLocals` is used during const checking to prove that a
-/// local has not been mutated via indirect assignment (e.g., `*p = 42`), the side-effects of a
-/// function call or inline assembly.
-pub struct MaybeBorrowedLocals<K = AnyBorrow> {
-    kind: K,
+/// immovable generators.
+pub struct MaybeBorrowedLocals {
     ignore_borrow_on_drop: bool,
 }
 
 impl MaybeBorrowedLocals {
     /// A dataflow analysis that records whether a pointer or reference exists that may alias the
     /// given local.
     pub fn all_borrows() -> Self {
-        MaybeBorrowedLocals { kind: AnyBorrow, ignore_borrow_on_drop: false }
-    }
-}
-
-impl MaybeMutBorrowedLocals<'mir, 'tcx> {
-    /// A dataflow analysis that records whether a pointer or reference exists that may *mutably*
-    /// alias the given local.
-    ///
-    /// This includes `&mut` and pointers derived from an `&mut`, as well as shared borrows of
-    /// types with interior mutability.
-    pub fn mut_borrows_only(
-        tcx: TyCtxt<'tcx>,
-        body: &'mir mir::Body<'tcx>,
-        param_env: ParamEnv<'tcx>,
-    ) -> Self {
-        MaybeBorrowedLocals {
-            kind: MutBorrow { body, tcx, param_env },
-            ignore_borrow_on_drop: false,
-        }
+        MaybeBorrowedLocals { ignore_borrow_on_drop: false }
     }
 }
 
-impl<K> MaybeBorrowedLocals<K> {
+impl MaybeBorrowedLocals {
     /// During dataflow analysis, ignore the borrow that may occur when a place is dropped.
     ///
     /// Drop terminators may call custom drop glue (`Drop::drop`), which takes `&mut self` as a
@@ -69,21 +40,14 @@ impl<K> MaybeBorrowedLocals<K> {
         MaybeBorrowedLocals { ignore_borrow_on_drop: true, ..self }
     }
 
-    fn transfer_function<'a, T>(&'a self, trans: &'a mut T) -> TransferFunction<'a, T, K> {
-        TransferFunction {
-            kind: &self.kind,
-            trans,
-            ignore_borrow_on_drop: self.ignore_borrow_on_drop,
-        }
+    fn transfer_function<'a, T>(&'a self, trans: &'a mut T) -> TransferFunction<'a, T> {
+        TransferFunction { trans, ignore_borrow_on_drop: self.ignore_borrow_on_drop }
     }
 }
 
-impl<K> AnalysisDomain<'tcx> for MaybeBorrowedLocals<K>
-where
-    K: BorrowAnalysisKind<'tcx>,
-{
+impl AnalysisDomain<'tcx> for MaybeBorrowedLocals {
     type Domain = BitSet<Local>;
-    const NAME: &'static str = K::ANALYSIS_NAME;
+    const NAME: &'static str = "maybe_borrowed_locals";
 
     fn bottom_value(&self, body: &mir::Body<'tcx>) -> Self::Domain {
         // bottom = unborrowed
@@ -95,10 +59,7 @@ where
     }
 }
 
-impl<K> GenKillAnalysis<'tcx> for MaybeBorrowedLocals<K>
-where
-    K: BorrowAnalysisKind<'tcx>,
-{
+impl GenKillAnalysis<'tcx> for MaybeBorrowedLocals {
     type Idx = Local;
 
     fn statement_effect(
@@ -131,16 +92,14 @@ where
 }
 
 /// A `Visitor` that defines the transfer function for `MaybeBorrowedLocals`.
-struct TransferFunction<'a, T, K> {
+struct TransferFunction<'a, T> {
     trans: &'a mut T,
-    kind: &'a K,
     ignore_borrow_on_drop: bool,
 }
 
-impl<T, K> Visitor<'tcx> for TransferFunction<'a, T, K>
+impl<T> Visitor<'tcx> for TransferFunction<'a, T>
 where
     T: GenKill<Local>,
-    K: BorrowAnalysisKind<'tcx>,
 {
     fn visit_statement(&mut self, stmt: &Statement<'tcx>, location: Location) {
         self.super_statement(stmt, location);
@@ -156,14 +115,14 @@ where
         self.super_rvalue(rvalue, location);
 
         match rvalue {
-            mir::Rvalue::AddressOf(mt, borrowed_place) => {
-                if !borrowed_place.is_indirect() && self.kind.in_address_of(*mt, *borrowed_place) {
+            mir::Rvalue::AddressOf(_mt, borrowed_place) => {
+                if !borrowed_place.is_indirect() {
                     self.trans.gen(borrowed_place.local);
                 }
             }
 
-            mir::Rvalue::Ref(_, kind, borrowed_place) => {
-                if !borrowed_place.is_indirect() && self.kind.in_ref(*kind, *borrowed_place) {
+            mir::Rvalue::Ref(_, _kind, borrowed_place) => {
+                if !borrowed_place.is_indirect() {
                     self.trans.gen(borrowed_place.local);
                 }
             }
@@ -211,64 +170,3 @@ where
         }
     }
 }
-
-pub struct AnyBorrow;
-
-pub struct MutBorrow<'mir, 'tcx> {
-    tcx: TyCtxt<'tcx>,
-    body: &'mir Body<'tcx>,
-    param_env: ParamEnv<'tcx>,
-}
-
-impl MutBorrow<'mir, 'tcx> {
-    /// `&` and `&raw` only allow mutation if the borrowed place is `!Freeze`.
-    ///
-    /// This assumes that it is UB to take the address of a struct field whose type is
-    /// `Freeze`, then use pointer arithmetic to derive a pointer to a *different* field of
-    /// that same struct whose type is `!Freeze`. If we decide that this is not UB, we will
-    /// have to check the type of the borrowed **local** instead of the borrowed **place**
-    /// below. See [rust-lang/unsafe-code-guidelines#134].
-    ///
-    /// [rust-lang/unsafe-code-guidelines#134]: https://github.com/rust-lang/unsafe-code-guidelines/issues/134
-    fn shared_borrow_allows_mutation(&self, place: Place<'tcx>) -> bool {
-        !place.ty(self.body, self.tcx).ty.is_freeze(self.tcx.at(DUMMY_SP), self.param_env)
-    }
-}
-
-pub trait BorrowAnalysisKind<'tcx> {
-    const ANALYSIS_NAME: &'static str;
-
-    fn in_address_of(&self, mt: Mutability, place: Place<'tcx>) -> bool;
-    fn in_ref(&self, kind: mir::BorrowKind, place: Place<'tcx>) -> bool;
-}
-
-impl BorrowAnalysisKind<'tcx> for AnyBorrow {
-    const ANALYSIS_NAME: &'static str = "maybe_borrowed_locals";
-
-    fn in_ref(&self, _: mir::BorrowKind, _: Place<'_>) -> bool {
-        true
-    }
-    fn in_address_of(&self, _: Mutability, _: Place<'_>) -> bool {
-        true
-    }
-}
-
-impl BorrowAnalysisKind<'tcx> for MutBorrow<'mir, 'tcx> {
-    const ANALYSIS_NAME: &'static str = "maybe_mut_borrowed_locals";
-
-    fn in_ref(&self, kind: mir::BorrowKind, place: Place<'tcx>) -> bool {
-        match kind {
-            mir::BorrowKind::Mut { .. } => true,
-            mir::BorrowKind::Shared | mir::BorrowKind::Shallow | mir::BorrowKind::Unique => {
-                self.shared_borrow_allows_mutation(place)
-            }
-        }
-    }
-
-    fn in_address_of(&self, mt: Mutability, place: Place<'tcx>) -> bool {
-        match mt {
-            Mutability::Mut => true,
-            Mutability::Not => self.shared_borrow_allows_mutation(place),
-        }
-    }
-}