Rollup of 14 pull requests

compiler/rustc_ast_lowering/src/lib.rs

@@ -1076,16 +1076,40 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
     fn lower_assoc_ty_constraint(
         &mut self,
         constraint: &AssocTyConstraint,
-        itctx: ImplTraitContext<'_, 'hir>,
+        mut itctx: ImplTraitContext<'_, 'hir>,
     ) -> hir::TypeBinding<'hir> {
         debug!("lower_assoc_ty_constraint(constraint={:?}, itctx={:?})", constraint, itctx);
 
-        if let Some(ref gen_args) = constraint.gen_args {
-            self.sess.span_fatal(
-                gen_args.span(),
-                "generic associated types in trait paths are currently not implemented",
-            );
-        }
+        // lower generic arguments of identifier in constraint
+        let gen_args = if let Some(ref gen_args) = constraint.gen_args {
+            let gen_args_ctor = match gen_args {
+                GenericArgs::AngleBracketed(ref data) => {
+                    self.lower_angle_bracketed_parameter_data(
+                        data,
+                        ParamMode::Explicit,
+                        itctx.reborrow(),
+                    )
+                    .0
+                }
+                GenericArgs::Parenthesized(ref data) => {
+                    let mut err = self.sess.struct_span_err(
+                        gen_args.span(),
+                        "parenthesized generic arguments cannot be used in associated type constraints"
+                    );
+                    // FIXME: try to write a suggestion here
+                    err.emit();
+                    self.lower_angle_bracketed_parameter_data(
+                        &data.as_angle_bracketed_args(),
+                        ParamMode::Explicit,
+                        itctx.reborrow(),
+                    )
+                    .0
+                }
+            };
+            self.arena.alloc(gen_args_ctor.into_generic_args(&self.arena))
+        } else {
+            self.arena.alloc(hir::GenericArgs::none())
+        };
 
         let kind = match constraint.kind {
             AssocTyConstraintKind::Equality { ref ty } => {
@@ -1182,6 +1206,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         hir::TypeBinding {
             hir_id: self.lower_node_id(constraint.id),
             ident: constraint.ident,
+            gen_args,
             kind,
             span: constraint.span,
         }

compiler/rustc_ast_lowering/src/path.rs

@@ -362,7 +362,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         }
     }
 
-    fn lower_angle_bracketed_parameter_data(
+    pub(crate) fn lower_angle_bracketed_parameter_data(
         &mut self,
         data: &AngleBracketedArgs,
         param_mode: ParamMode,
@@ -426,6 +426,9 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
     ) -> hir::TypeBinding<'hir> {
         let ident = Ident::with_dummy_span(hir::FN_OUTPUT_NAME);
         let kind = hir::TypeBindingKind::Equality { ty };
-        hir::TypeBinding { hir_id: self.next_id(), span, ident, kind }
+        let args = arena_vec![self;];
+        let bindings = arena_vec![self;];
+        let gen_args = self.arena.alloc(hir::GenericArgs { args, bindings, parenthesized: false });
+        hir::TypeBinding { hir_id: self.next_id(), gen_args, span, ident, kind }
     }
 }

compiler/rustc_data_structures/src/profiling.rs

@@ -590,24 +590,21 @@ pub fn print_time_passes_entry(
     end_rss: Option<usize>,
 ) {
     let rss_to_mb = |rss| (rss as f64 / 1_000_000.0).round() as usize;
+    let rss_change_to_mb = |rss| (rss as f64 / 1_000_000.0).round() as i128;
 
     let mem_string = match (start_rss, end_rss) {
         (Some(start_rss), Some(end_rss)) => {
-            // It's tempting to add the change in RSS from start to end, but its somewhat confusing
-            // and misleading when looking at time-passes output. Consider two adjacent entries:
-            //
-            // time:  10.000; rss start:  1000MB, end:  1000MB, change:     0MB     pass1
-            // time:   5.000; rss start:  2000MB, end:  2000MB, change:     0MB     pass2
-            //
-            // If you're looking for jumps in RSS based on the change column, you miss the fact
-            // that a 1GB jump happened between pass1 and pass2 (supposing pass1 and pass2 actually
-            // occur sequentially and pass1 isn't just nested within pass2). It's easy to imagine
-            // someone missing this or being confused by the fact that the change is zero.
-
-            format!("; rss: {:>5}MB -> {:>5}MB", rss_to_mb(start_rss), rss_to_mb(end_rss))
+            let change_rss = end_rss as i128 - start_rss as i128;
+
+            format!(
+                "; rss: {:>4}MB -> {:>4}MB ({:>+5}MB)",
+                rss_to_mb(start_rss),
+                rss_to_mb(end_rss),
+                rss_change_to_mb(change_rss),
+            )
         }
-        (Some(start_rss), None) => format!("; rss start: {:>5}MB", rss_to_mb(start_rss)),
-        (None, Some(end_rss)) => format!("; rss end: {:5>}MB", rss_to_mb(end_rss)),
+        (Some(start_rss), None) => format!("; rss start: {:>4}MB", rss_to_mb(start_rss)),
+        (None, Some(end_rss)) => format!("; rss end: {:>4}MB", rss_to_mb(end_rss)),
         (None, None) => String::new(),
     };
 

compiler/rustc_error_codes/src/error_codes/E0463.md

@@ -11,3 +11,24 @@ extern crate cake_is_a_lie; // error: can't find crate for `cake_is_a_lie`
 You need to link your code to the relevant crate in order to be able to use it
 (through Cargo or the `-L` option of rustc example). Plugins are crates as
 well, and you link to them the same way.
+
+## Common causes
+
+- The crate is not present at all. If using Cargo, add it to `[dependencies]`
+  in Cargo.toml.
+- The crate is present, but under a different name. If using Cargo, look for
+  `package = ` under `[dependencies]` in Cargo.toml.
+
+## Common causes for missing `std` or `core`
+
+- You are cross-compiling for a target which doesn't have `std` prepackaged.
+  Consider one of the following:
+  + Adding a pre-compiled version of std with `rustup target add`
+  + Building std from source with `cargo build -Z build-std`
+  + Using `#![no_std]` at the crate root, so you won't need `std` in the first
+    place.
+- You are developing the compiler itself and haven't built libstd from source.
+  You can usually build it with `x.py build library/std`. More information
+  about x.py is available in the [rustc-dev-guide].
+
+[rustc-dev-guide]: https://rustc-dev-guide.rust-lang.org/building/how-to-build-and-run.html#building-the-compiler

compiler/rustc_feature/src/active.rs

@@ -631,6 +631,9 @@ declare_features! (
 
     /// Allows `extern "C-cmse-nonsecure-call" fn()`.
     (active, abi_c_cmse_nonsecure_call, "1.51.0", Some(81391), None),
+
+    /// Lessens the requirements for structs to implement `Unsize`.
+    (active, relaxed_struct_unsize, "1.51.0", Some(1), None),
     // -------------------------------------------------------------------------
     // feature-group-end: actual feature gates
     // -------------------------------------------------------------------------

compiler/rustc_hir/src/hir.rs

@@ -2015,6 +2015,7 @@ pub struct TypeBinding<'hir> {
     pub hir_id: HirId,
     #[stable_hasher(project(name))]
     pub ident: Ident,
+    pub gen_args: &'hir GenericArgs<'hir>,
     pub kind: TypeBindingKind<'hir>,
     pub span: Span,
 }

compiler/rustc_hir/src/intravisit.rs

@@ -781,6 +781,7 @@ pub fn walk_assoc_type_binding<'v, V: Visitor<'v>>(
 ) {
     visitor.visit_id(type_binding.hir_id);
     visitor.visit_ident(type_binding.ident);
+    visitor.visit_generic_args(type_binding.span, type_binding.gen_args);
     match type_binding.kind {
         TypeBindingKind::Equality { ref ty } => {
             visitor.visit_ty(ty);

compiler/rustc_hir_pretty/src/lib.rs

@@ -1840,6 +1840,7 @@ impl<'a> State<'a> {
             for binding in generic_args.bindings.iter() {
                 start_or_comma(self);
                 self.print_ident(binding.ident);
+                self.print_generic_args(binding.gen_args, false, false);
                 self.s.space();
                 match generic_args.bindings[0].kind {
                     hir::TypeBindingKind::Equality { ref ty } => {

compiler/rustc_index/src/bit_set.rs

@@ -707,6 +707,18 @@ impl<T: Idx> GrowableBitSet<T> {
         self.bit_set.insert(elem)
     }
 
+    /// Returns `true` if the set has changed.
+    #[inline]
+    pub fn remove(&mut self, elem: T) -> bool {
+        self.ensure(elem.index() + 1);
+        self.bit_set.remove(elem)
+    }
+
+    #[inline]
+    pub fn is_empty(&self) -> bool {
+        self.bit_set.is_empty()
+    }
+
     #[inline]
     pub fn contains(&self, elem: T) -> bool {
         let (word_index, mask) = word_index_and_mask(elem);

compiler/rustc_index/src/bit_set/tests.rs

@@ -1,6 +1,7 @@
 use super::*;
 
 extern crate test;
+use std::hint::black_box;
 use test::Bencher;
 
 #[test]
@@ -364,3 +365,36 @@ fn union_hybrid_sparse_full_small_domain(b: &mut Bencher) {
         sparse.union(&dense);
     })
 }
+
+#[bench]
+fn bench_insert(b: &mut Bencher) {
+    let mut bs = BitSet::new_filled(99999usize);
+    b.iter(|| {
+        black_box(bs.insert(black_box(100u32)));
+    });
+}
+
+#[bench]
+fn bench_remove(b: &mut Bencher) {
+    let mut bs = BitSet::new_filled(99999usize);
+    b.iter(|| {
+        black_box(bs.remove(black_box(100u32)));
+    });
+}
+
+#[bench]
+fn bench_iter(b: &mut Bencher) {
+    let bs = BitSet::new_filled(99999usize);
+    b.iter(|| {
+        bs.iter().map(|b: usize| black_box(b)).for_each(drop);
+    });
+}
+
+#[bench]
+fn bench_intersect(b: &mut Bencher) {
+    let mut ba: BitSet<u32> = BitSet::new_filled(99999usize);
+    let bb = BitSet::new_filled(99999usize);
+    b.iter(|| {
+        ba.intersect(black_box(&bb));
+    });
+}

compiler/rustc_middle/src/ty/sty.rs

@@ -1132,8 +1132,16 @@ impl<'tcx> ProjectionTy<'tcx> {
     /// For example, if this is a projection of `<T as Iterator>::Item`,
     /// then this function would return a `T: Iterator` trait reference.
     pub fn trait_ref(&self, tcx: TyCtxt<'tcx>) -> ty::TraitRef<'tcx> {
+        // FIXME: This method probably shouldn't exist at all, since it's not
+        // clear what this method really intends to do. Be careful when
+        // using this method since the resulting TraitRef additionally
+        // contains the substs for the assoc_item, which strictly speaking
+        // is not correct
         let def_id = tcx.associated_item(self.item_def_id).container.id();
-        ty::TraitRef { def_id, substs: self.substs.truncate_to(tcx, tcx.generics_of(def_id)) }
+        // Include substitutions for generic arguments of associated types
+        let assoc_item = tcx.associated_item(self.item_def_id);
+        let substs_assoc_item = self.substs.truncate_to(tcx, tcx.generics_of(assoc_item.def_id));
+        ty::TraitRef { def_id, substs: substs_assoc_item }
     }
 
     pub fn self_ty(&self) -> Ty<'tcx> {

compiler/rustc_parse/src/lexer/mod.rs

@@ -14,7 +14,7 @@ mod tokentrees;
 mod unescape_error_reporting;
 mod unicode_chars;
 
-use unescape_error_reporting::{emit_unescape_error, push_escaped_char};
+use unescape_error_reporting::{emit_unescape_error, escaped_char};
 
 #[derive(Clone, Debug)]
 pub struct UnmatchedBrace {
@@ -122,11 +122,9 @@ impl<'a> StringReader<'a> {
         m: &str,
         c: char,
     ) -> DiagnosticBuilder<'a> {
-        let mut m = m.to_string();
-        m.push_str(": ");
-        push_escaped_char(&mut m, c);
-
-        self.sess.span_diagnostic.struct_span_fatal(self.mk_sp(from_pos, to_pos), &m[..])
+        self.sess
+            .span_diagnostic
+            .struct_span_fatal(self.mk_sp(from_pos, to_pos), &format!("{}: {}", m, escaped_char(c)))
     }
 
     /// Turns simple `rustc_lexer::TokenKind` enum into a rich
@@ -421,7 +419,7 @@ impl<'a> StringReader<'a> {
         let content_start = start + BytePos(prefix_len);
         let content_end = suffix_start - BytePos(postfix_len);
         let id = self.symbol_from_to(content_start, content_end);
-        self.validate_literal_escape(mode, content_start, content_end);
+        self.validate_literal_escape(mode, content_start, content_end, prefix_len, postfix_len);
         (lit_kind, id)
     }
 
@@ -525,17 +523,29 @@ impl<'a> StringReader<'a> {
         .raise();
     }
 
-    fn validate_literal_escape(&self, mode: Mode, content_start: BytePos, content_end: BytePos) {
+    fn validate_literal_escape(
+        &self,
+        mode: Mode,
+        content_start: BytePos,
+        content_end: BytePos,
+        prefix_len: u32,
+        postfix_len: u32,
+    ) {
         let lit_content = self.str_from_to(content_start, content_end);
         unescape::unescape_literal(lit_content, mode, &mut |range, result| {
             // Here we only check for errors. The actual unescaping is done later.
             if let Err(err) = result {
-                let span_with_quotes =
-                    self.mk_sp(content_start - BytePos(1), content_end + BytePos(1));
+                let span_with_quotes = self
+                    .mk_sp(content_start - BytePos(prefix_len), content_end + BytePos(postfix_len));
+                let (start, end) = (range.start as u32, range.end as u32);
+                let lo = content_start + BytePos(start);
+                let hi = lo + BytePos(end - start);
+                let span = self.mk_sp(lo, hi);
                 emit_unescape_error(
                     &self.sess.span_diagnostic,
                     lit_content,
                     span_with_quotes,
+                    span,
                     mode,
                     range,
                     err,