Merge from rustc

Author: RalfJung

Cargo.lock

@@ -2580,9 +2580,9 @@ checksum = "dbf0c48bc1d91375ae5c3cd81e3722dff1abcf81a30960240640d223f59fe0e5"
 
 [[package]]
 name = "proc-macro2"
-version = "1.0.56"
+version = "1.0.60"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2b63bdb0cd06f1f4dedf69b254734f9b45af66e4a031e42a7480257d9898b435"
+checksum = "dec2b086b7a862cf4de201096214fa870344cf922b2b30c167badb3af3195406"
 dependencies = [
  "unicode-ident",
 ]

compiler/rustc_borrowck/src/dataflow.rs

@@ -125,15 +125,9 @@ pub struct Borrows<'a, 'tcx> {
     borrows_out_of_scope_at_location: FxIndexMap<Location, Vec<BorrowIndex>>,
 }
 
-struct StackEntry {
-    bb: mir::BasicBlock,
-    lo: usize,
-    hi: usize,
-}
-
 struct OutOfScopePrecomputer<'a, 'tcx> {
     visited: BitSet<mir::BasicBlock>,
-    visit_stack: Vec<StackEntry>,
+    visit_stack: Vec<mir::BasicBlock>,
     body: &'a Body<'tcx>,
     regioncx: &'a RegionInferenceContext<'tcx>,
     borrows_out_of_scope_at_location: FxIndexMap<Location, Vec<BorrowIndex>>,
@@ -158,68 +152,66 @@ impl<'tcx> OutOfScopePrecomputer<'_, 'tcx> {
         borrow_region: RegionVid,
         first_location: Location,
     ) {
-        // We visit one BB at a time. The complication is that we may start in the
-        // middle of the first BB visited (the one containing `first_location`), in which
-        // case we may have to later on process the first part of that BB if there
-        // is a path back to its start.
-
-        // For visited BBs, we record the index of the first statement processed.
-        // (In fully processed BBs this index is 0.) Note also that we add BBs to
-        // `visited` once they are added to `stack`, before they are actually
-        // processed, because this avoids the need to look them up again on
-        // completion.
-        self.visited.insert(first_location.block);
-
         let first_block = first_location.block;
-        let mut first_lo = first_location.statement_index;
-        let first_hi = self.body[first_block].statements.len();
+        let first_bb_data = &self.body.basic_blocks[first_block];
+
+        // This is the first block, we only want to visit it from the creation of the borrow at
+        // `first_location`.
+        let first_lo = first_location.statement_index;
+        let first_hi = first_bb_data.statements.len();
+
+        if let Some(kill_stmt) = self.regioncx.first_non_contained_inclusive(
+            borrow_region,
+            first_block,
+            first_lo,
+            first_hi,
+        ) {
+            let kill_location = Location { block: first_block, statement_index: kill_stmt };
+            // If region does not contain a point at the location, then add to list and skip
+            // successor locations.
+            debug!("borrow {:?} gets killed at {:?}", borrow_index, kill_location);
+            self.borrows_out_of_scope_at_location
+                .entry(kill_location)
+                .or_default()
+                .push(borrow_index);
+
+            // The borrow is already dead, there is no need to visit other blocks.
+            return;
+        }
 
-        self.visit_stack.push(StackEntry { bb: first_block, lo: first_lo, hi: first_hi });
+        // The borrow is not dead. Add successor BBs to the work list, if necessary.
+        for succ_bb in first_bb_data.terminator().successors() {
+            if self.visited.insert(succ_bb) {
+                self.visit_stack.push(succ_bb);
+            }
+        }
 
-        'preorder: while let Some(StackEntry { bb, lo, hi }) = self.visit_stack.pop() {
+        // We may end up visiting `first_block` again. This is not an issue: we know at this point
+        // that it does not kill the borrow in the `first_lo..=first_hi` range, so checking the
+        // `0..first_lo` range and the `0..first_hi` range give the same result.
+        while let Some(block) = self.visit_stack.pop() {
+            let bb_data = &self.body[block];
+            let num_stmts = bb_data.statements.len();
             if let Some(kill_stmt) =
-                self.regioncx.first_non_contained_inclusive(borrow_region, bb, lo, hi)
+                self.regioncx.first_non_contained_inclusive(borrow_region, block, 0, num_stmts)
             {
-                let kill_location = Location { block: bb, statement_index: kill_stmt };
+                let kill_location = Location { block, statement_index: kill_stmt };
                 // If region does not contain a point at the location, then add to list and skip
                 // successor locations.
                 debug!("borrow {:?} gets killed at {:?}", borrow_index, kill_location);
                 self.borrows_out_of_scope_at_location
                     .entry(kill_location)
                     .or_default()
                     .push(borrow_index);
-                continue 'preorder;
-            }
 
-            // If we process the first part of the first basic block (i.e. we encounter that block
-            // for the second time), we no longer have to visit its successors again.
-            if bb == first_block && hi != first_hi {
+                // We killed the borrow, so we do not visit this block's successors.
                 continue;
             }
 
             // Add successor BBs to the work list, if necessary.
-            let bb_data = &self.body[bb];
-            debug_assert!(hi == bb_data.statements.len());
             for succ_bb in bb_data.terminator().successors() {
-                if !self.visited.insert(succ_bb) {
-                    if succ_bb == first_block && first_lo > 0 {
-                        // `succ_bb` has been seen before. If it wasn't
-                        // fully processed, add its first part to `stack`
-                        // for processing.
-                        self.visit_stack.push(StackEntry { bb: succ_bb, lo: 0, hi: first_lo - 1 });
-
-                        // And update this entry with 0, to represent the
-                        // whole BB being processed.
-                        first_lo = 0;
-                    }
-                } else {
-                    // succ_bb hasn't been seen before. Add it to
-                    // `stack` for processing.
-                    self.visit_stack.push(StackEntry {
-                        bb: succ_bb,
-                        lo: 0,
-                        hi: self.body[succ_bb].statements.len(),
-                    });
+                if self.visited.insert(succ_bb) {
+                    self.visit_stack.push(succ_bb);
                 }
             }
         }

compiler/rustc_expand/src/proc_macro_server.rs

@@ -2,7 +2,7 @@ use crate::base::ExtCtxt;
 use pm::bridge::{
     server, DelimSpan, Diagnostic, ExpnGlobals, Group, Ident, LitKind, Literal, Punct, TokenTree,
 };
-use pm::{Delimiter, Level, LineColumn};
+use pm::{Delimiter, Level};
 use rustc_ast as ast;
 use rustc_ast::token;
 use rustc_ast::tokenstream::{self, Spacing::*, TokenStream};
@@ -648,23 +648,22 @@ impl server::Span for Rustc<'_, '_> {
 
         Range { start: relative_start_pos.0 as usize, end: relative_end_pos.0 as usize }
     }
-
-    fn start(&mut self, span: Self::Span) -> LineColumn {
-        let loc = self.sess().source_map().lookup_char_pos(span.lo());
-        LineColumn { line: loc.line, column: loc.col.to_usize() }
+    fn start(&mut self, span: Self::Span) -> Self::Span {
+        span.shrink_to_lo()
     }
 
-    fn end(&mut self, span: Self::Span) -> LineColumn {
-        let loc = self.sess().source_map().lookup_char_pos(span.hi());
-        LineColumn { line: loc.line, column: loc.col.to_usize() }
+    fn end(&mut self, span: Self::Span) -> Self::Span {
+        span.shrink_to_hi()
     }
 
-    fn before(&mut self, span: Self::Span) -> Self::Span {
-        span.shrink_to_lo()
+    fn line(&mut self, span: Self::Span) -> usize {
+        let loc = self.sess().source_map().lookup_char_pos(span.lo());
+        loc.line
     }
 
-    fn after(&mut self, span: Self::Span) -> Self::Span {
-        span.shrink_to_hi()
+    fn column(&mut self, span: Self::Span) -> usize {
+        let loc = self.sess().source_map().lookup_char_pos(span.lo());
+        loc.col.to_usize() + 1
     }
 
     fn join(&mut self, first: Self::Span, second: Self::Span) -> Option<Self::Span> {

compiler/rustc_hir_analysis/src/astconv/bounds.rs

@@ -9,12 +9,12 @@ use rustc_span::symbol::Ident;
 use rustc_span::{ErrorGuaranteed, Span};
 use rustc_trait_selection::traits;
 
-use crate::astconv::{AstConv, ConvertedBinding, ConvertedBindingKind};
+use crate::astconv::{
+    AstConv, ConvertedBinding, ConvertedBindingKind, OnlySelfBounds, PredicateFilter,
+};
 use crate::bounds::Bounds;
 use crate::errors::{MultipleRelaxedDefaultBounds, ValueOfAssociatedStructAlreadySpecified};
 
-use super::OnlySelfBounds;
-
 impl<'tcx> dyn AstConv<'tcx> + '_ {
     /// Sets `implicitly_sized` to true on `Bounds` if necessary
     pub(crate) fn add_implicitly_sized(
@@ -176,47 +176,39 @@ impl<'tcx> dyn AstConv<'tcx> + '_ {
         &self,
         param_ty: Ty<'tcx>,
         ast_bounds: &[hir::GenericBound<'_>],
-        only_self_bounds: OnlySelfBounds,
+        filter: PredicateFilter,
     ) -> Bounds<'tcx> {
         let mut bounds = Bounds::default();
-        self.add_bounds(
-            param_ty,
-            ast_bounds.iter(),
-            &mut bounds,
-            ty::List::empty(),
-            only_self_bounds,
-        );
-        debug!(?bounds);
 
-        bounds
-    }
-
-    /// Convert the bounds in `ast_bounds` that refer to traits which define an associated type
-    /// named `assoc_name` into ty::Bounds. Ignore the rest.
-    pub(crate) fn compute_bounds_that_match_assoc_item(
-        &self,
-        param_ty: Ty<'tcx>,
-        ast_bounds: &[hir::GenericBound<'_>],
-        assoc_name: Ident,
-    ) -> Bounds<'tcx> {
-        let mut result = Vec::new();
-
-        for ast_bound in ast_bounds {
-            if let Some(trait_ref) = ast_bound.trait_ref()
-                && let Some(trait_did) = trait_ref.trait_def_id()
-                && self.tcx().trait_may_define_assoc_item(trait_did, assoc_name)
-            {
-                result.push(ast_bound.clone());
+        let only_self_bounds = match filter {
+            PredicateFilter::All | PredicateFilter::SelfAndAssociatedTypeBounds => {
+                OnlySelfBounds(false)
             }
-        }
+            PredicateFilter::SelfOnly | PredicateFilter::SelfThatDefines(_) => OnlySelfBounds(true),
+        };
 
-        let mut bounds = Bounds::default();
         self.add_bounds(
             param_ty,
-            result.iter(),
+            ast_bounds.iter().filter(|bound| {
+                match filter {
+                PredicateFilter::All
+                | PredicateFilter::SelfOnly
+                | PredicateFilter::SelfAndAssociatedTypeBounds => true,
+                PredicateFilter::SelfThatDefines(assoc_name) => {
+                    if let Some(trait_ref) = bound.trait_ref()
+                        && let Some(trait_did) = trait_ref.trait_def_id()
+                        && self.tcx().trait_may_define_assoc_item(trait_did, assoc_name)
+                    {
+                        true
+                    } else {
+                        false
+                    }
+                }
+            }
+            }),
             &mut bounds,
             ty::List::empty(),
-            OnlySelfBounds(true),
+            only_self_bounds,
         );
         debug!(?bounds);
 

compiler/rustc_hir_analysis/src/astconv/mod.rs

@@ -58,6 +58,24 @@ pub struct PathSeg(pub DefId, pub usize);
 #[derive(Copy, Clone, Debug)]
 pub struct OnlySelfBounds(pub bool);
 
+#[derive(Copy, Clone, Debug)]
+pub enum PredicateFilter {
+    /// All predicates may be implied by the trait.
+    All,
+
+    /// Only traits that reference `Self: ..` are implied by the trait.
+    SelfOnly,
+
+    /// Only traits that reference `Self: ..` and define an associated type
+    /// with the given ident are implied by the trait.
+    SelfThatDefines(Ident),
+
+    /// Only traits that reference `Self: ..` and their associated type bounds.
+    /// For example, given `Self: Tr<A: B>`, this would expand to `Self: Tr`
+    /// and `<Self as Tr>::A: B`.
+    SelfAndAssociatedTypeBounds,
+}
+
 pub trait AstConv<'tcx> {
     fn tcx(&self) -> TyCtxt<'tcx>;
 

compiler/rustc_hir_analysis/src/collect/item_bounds.rs

@@ -1,5 +1,5 @@
 use super::ItemCtxt;
-use crate::astconv::{AstConv, OnlySelfBounds};
+use crate::astconv::{AstConv, PredicateFilter};
 use rustc_hir as hir;
 use rustc_infer::traits::util;
 use rustc_middle::ty::subst::InternalSubsts;
@@ -26,7 +26,7 @@ fn associated_type_bounds<'tcx>(
     );
 
     let icx = ItemCtxt::new(tcx, assoc_item_def_id);
-    let mut bounds = icx.astconv().compute_bounds(item_ty, ast_bounds, OnlySelfBounds(false));
+    let mut bounds = icx.astconv().compute_bounds(item_ty, ast_bounds, PredicateFilter::All);
     // Associated types are implicitly sized unless a `?Sized` bound is found
     icx.astconv().add_implicitly_sized(&mut bounds, item_ty, ast_bounds, None, span);
 
@@ -68,7 +68,7 @@ fn opaque_type_bounds<'tcx>(
 ) -> &'tcx [(ty::Clause<'tcx>, Span)] {
     ty::print::with_no_queries!({
         let icx = ItemCtxt::new(tcx, opaque_def_id);
-        let mut bounds = icx.astconv().compute_bounds(item_ty, ast_bounds, OnlySelfBounds(false));
+        let mut bounds = icx.astconv().compute_bounds(item_ty, ast_bounds, PredicateFilter::All);
         // Opaque types are implicitly sized unless a `?Sized` bound is found
         icx.astconv().add_implicitly_sized(&mut bounds, item_ty, ast_bounds, None, span);
         debug!(?bounds);