Rollup of 14 pull requests

compiler/rustc_data_structures/src/vec_map.rs

@@ -1,4 +1,5 @@
 use std::borrow::Borrow;
+use std::fmt::Debug;
 use std::iter::FromIterator;
 use std::slice::Iter;
 use std::vec::IntoIter;
@@ -12,7 +13,8 @@ pub struct VecMap<K, V>(Vec<(K, V)>);
 
 impl<K, V> VecMap<K, V>
 where
-    K: PartialEq,
+    K: Debug + PartialEq,
+    V: Debug,
 {
     pub fn new() -> Self {
         VecMap(Default::default())
@@ -37,14 +39,31 @@ where
         self.0.iter().find(|(key, _)| k == key.borrow()).map(|elem| &elem.1)
     }
 
-    /// Returns the value corresponding to the supplied predicate filter.
+    /// Returns the any value corresponding to the supplied predicate filter.
     ///
     /// The supplied predicate will be applied to each (key, value) pair and it will return a
     /// reference to the values where the predicate returns `true`.
-    pub fn get_by(&self, mut predicate: impl FnMut(&(K, V)) -> bool) -> Option<&V> {
+    pub fn any_value_matching(&self, mut predicate: impl FnMut(&(K, V)) -> bool) -> Option<&V> {
         self.0.iter().find(|kv| predicate(kv)).map(|elem| &elem.1)
     }
 
+    /// Returns the value corresponding to the supplied predicate filter. It crashes if there's
+    /// more than one matching element.
+    ///
+    /// The supplied predicate will be applied to each (key, value) pair and it will return a
+    /// reference to the value where the predicate returns `true`.
+    pub fn get_value_matching(&self, mut predicate: impl FnMut(&(K, V)) -> bool) -> Option<&V> {
+        let mut filter = self.0.iter().filter(|kv| predicate(kv));
+        let (_, value) = filter.next()?;
+        // This should return just one element, otherwise it's a bug
+        assert!(
+            filter.next().is_none(),
+            "Collection {:?} should have just one matching element",
+            self
+        );
+        Some(value)
+    }
+
     /// Returns `true` if the map contains a value for the specified key.
     ///
     /// The key may be any borrowed form of the map's key type,
@@ -131,7 +150,7 @@ impl<K, V> IntoIterator for VecMap<K, V> {
     }
 }
 
-impl<K: PartialEq, V> Extend<(K, V)> for VecMap<K, V> {
+impl<K: PartialEq + Debug, V: Debug> Extend<(K, V)> for VecMap<K, V> {
     fn extend<I: IntoIterator<Item = (K, V)>>(&mut self, iter: I) {
         for (k, v) in iter {
             self.insert(k, v);

compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs

@@ -1857,12 +1857,37 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
                 }
             }
             GeneratorInteriorOrUpvar::Upvar(upvar_span) => {
+                // `Some(ref_ty)` if `target_ty` is `&T` and `T` fails to impl `Sync`
+                let refers_to_non_sync = match target_ty.kind() {
+                    ty::Ref(_, ref_ty, _) => match self.evaluate_obligation(&obligation) {
+                        Ok(eval) if !eval.may_apply() => Some(ref_ty),
+                        _ => None,
+                    },
+                    _ => None,
+                };
+
+                let (span_label, span_note) = match refers_to_non_sync {
+                    // if `target_ty` is `&T` and `T` fails to impl `Sync`,
+                    // include suggestions to make `T: Sync` so that `&T: Send`
+                    Some(ref_ty) => (
+                        format!(
+                            "has type `{}` which {}, because `{}` is not `Sync`",
+                            target_ty, trait_explanation, ref_ty
+                        ),
+                        format!(
+                            "captured value {} because `&` references cannot be sent unless their referent is `Sync`",
+                            trait_explanation
+                        ),
+                    ),
+                    None => (
+                        format!("has type `{}` which {}", target_ty, trait_explanation),
+                        format!("captured value {}", trait_explanation),
+                    ),
+                };
+
                 let mut span = MultiSpan::from_span(upvar_span);
-                span.push_span_label(
-                    upvar_span,
-                    format!("has type `{}` which {}", target_ty, trait_explanation),
-                );
-                err.span_note(span, &format!("captured value {}", trait_explanation));
+                span.push_span_label(upvar_span, span_label);
+                err.span_note(span, &span_note);
             }
         }
 

compiler/rustc_typeck/src/collect/type_of.rs

@@ -364,7 +364,7 @@ pub(super) fn type_of(tcx: TyCtxt<'_>, def_id: DefId) -> Ty<'_> {
                     let concrete_ty = tcx
                         .mir_borrowck(owner.expect_local())
                         .concrete_opaque_types
-                        .get_by(|(key, _)| key.def_id == def_id.to_def_id())
+                        .get_value_matching(|(key, _)| key.def_id == def_id.to_def_id())
                         .map(|concrete_ty| *concrete_ty)
                         .unwrap_or_else(|| {
                             tcx.sess.delay_span_bug(
@@ -512,8 +512,15 @@ fn find_opaque_ty_constraints(tcx: TyCtxt<'_>, def_id: LocalDefId) -> Ty<'_> {
 
     struct ConstraintLocator<'tcx> {
         tcx: TyCtxt<'tcx>,
+
+        /// def_id of the opaque type whose defining uses are being checked
         def_id: DefId,
-        // (first found type span, actual type)
+
+        /// as we walk the defining uses, we are checking that all of them
+        /// define the same hidden type. This variable is set to `Some`
+        /// with the first type that we find, and then later types are
+        /// checked against it (we also carry the span of that first
+        /// type).
         found: Option<(Span, Ty<'tcx>)>,
     }
 
@@ -531,7 +538,7 @@ fn find_opaque_ty_constraints(tcx: TyCtxt<'_>, def_id: LocalDefId) -> Ty<'_> {
                 .tcx
                 .typeck(def_id)
                 .concrete_opaque_types
-                .get_by(|(key, _)| key.def_id == self.def_id)
+                .any_value_matching(|(key, _)| key.def_id == self.def_id)
                 .is_none()
             {
                 debug!("no constraints in typeck results");

config.toml.example

@@ -38,7 +38,7 @@ changelog-seen = 2
 # This is false by default so that distributions don't unexpectedly download
 # LLVM from the internet.
 #
-# All tier 1 targets are currently supported; set this to `"if-supported"` if
+# All tier 1 targets are currently supported; set this to `"if-available"` if
 # you are not sure whether you're on a tier 1 target.
 #
 # We also currently only support this when building LLVM for the build triple.

library/alloc/src/collections/btree/map.rs

@@ -935,6 +935,7 @@ impl<K, V> BTreeMap<K, V> {
     /// Retains only the elements specified by the predicate.
     ///
     /// In other words, remove all pairs `(k, v)` such that `f(&k, &mut v)` returns `false`.
+    /// The elements are visited in ascending key order.
     ///
     /// # Examples
     ///

library/alloc/src/collections/btree/set.rs

@@ -846,6 +846,7 @@ impl<T> BTreeSet<T> {
     /// Retains only the elements specified by the predicate.
     ///
     /// In other words, remove all elements `e` such that `f(&e)` returns `false`.
+    /// The elements are visited in ascending order.
     ///
     /// # Examples
     ///

library/alloc/src/lib.rs

@@ -56,6 +56,10 @@
 //! [`Rc`]: rc
 //! [`RefCell`]: core::cell
 
+// To run liballoc tests without x.py without ending up with two copies of liballoc, Miri needs to be
+// able to "empty" this crate. See <https://github.com/rust-lang/miri-test-libstd/issues/4>.
+// rustc itself never sets the feature, so this line has no affect there.
+#![cfg(any(not(feature = "miri-test-libstd"), test, doctest))]
 #![allow(unused_attributes)]
 #![stable(feature = "alloc", since = "1.36.0")]
 #![doc(

library/core/src/lib.rs

@@ -49,6 +49,10 @@
 //
 // This cfg won't affect doc tests.
 #![cfg(not(test))]
+// To run libcore tests without x.py without ending up with two copies of libcore, Miri needs to be
+// able to "empty" this crate. See <https://github.com/rust-lang/miri-test-libstd/issues/4>.
+// rustc itself never sets the feature, so this line has no affect there.
+#![cfg(any(not(feature = "miri-test-libstd"), test, doctest))]
 #![stable(feature = "core", since = "1.6.0")]
 #![doc(
     html_playground_url = "https://play.rust-lang.org/",

library/std/src/collections/hash/map.rs

@@ -934,6 +934,7 @@ where
     /// Retains only the elements specified by the predicate.
     ///
     /// In other words, remove all pairs `(k, v)` such that `f(&k, &mut v)` returns `false`.
+    /// The elements are visited in unsorted (and unspecified) order.
     ///
     /// # Examples
     ///

library/std/src/collections/hash/set.rs

@@ -912,6 +912,7 @@ where
     /// Retains only the elements specified by the predicate.
     ///
     /// In other words, remove all elements `e` such that `f(&e)` returns `false`.
+    /// The elements are visited in unsorted (and unspecified) order.
     ///
     /// # Examples
     ///

library/std/src/io/buffered/bufwriter.rs

@@ -68,7 +68,7 @@ use crate::ptr;
 /// [`flush`]: BufWriter::flush
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct BufWriter<W: Write> {
-    inner: Option<W>,
+    inner: W,
     // The buffer. Avoid using this like a normal `Vec` in common code paths.
     // That is, don't use `buf.push`, `buf.extend_from_slice`, or any other
     // methods that require bounds checking or the like. This makes an enormous
@@ -112,7 +112,7 @@ impl<W: Write> BufWriter<W> {
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn with_capacity(capacity: usize, inner: W) -> BufWriter<W> {
-        BufWriter { inner: Some(inner), buf: Vec::with_capacity(capacity), panicked: false }
+        BufWriter { inner, buf: Vec::with_capacity(capacity), panicked: false }
     }
 
     /// Send data in our local buffer into the inner writer, looping as
@@ -161,10 +161,9 @@ impl<W: Write> BufWriter<W> {
         }
 
         let mut guard = BufGuard::new(&mut self.buf);
-        let inner = self.inner.as_mut().unwrap();
         while !guard.done() {
             self.panicked = true;
-            let r = inner.write(guard.remaining());
+            let r = self.inner.write(guard.remaining());
             self.panicked = false;
 
             match r {
@@ -212,7 +211,7 @@ impl<W: Write> BufWriter<W> {
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn get_ref(&self) -> &W {
-        self.inner.as_ref().unwrap()
+        &self.inner
     }
 
     /// Gets a mutable reference to the underlying writer.
@@ -232,7 +231,7 @@ impl<W: Write> BufWriter<W> {
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn get_mut(&mut self) -> &mut W {
-        self.inner.as_mut().unwrap()
+        &mut self.inner
     }
 
     /// Returns a reference to the internally buffered data.
@@ -308,7 +307,7 @@ impl<W: Write> BufWriter<W> {
     pub fn into_inner(mut self) -> Result<W, IntoInnerError<BufWriter<W>>> {
         match self.flush_buf() {
             Err(e) => Err(IntoInnerError::new(self, e)),
-            Ok(()) => Ok(self.inner.take().unwrap()),
+            Ok(()) => Ok(self.into_raw_parts().0),
         }
     }
 
@@ -339,7 +338,12 @@ impl<W: Write> BufWriter<W> {
     pub fn into_raw_parts(mut self) -> (W, Result<Vec<u8>, WriterPanicked>) {
         let buf = mem::take(&mut self.buf);
         let buf = if !self.panicked { Ok(buf) } else { Err(WriterPanicked { buf }) };
-        (self.inner.take().unwrap(), buf)
+
+        // SAFETY: forget(self) prevents double dropping inner
+        let inner = unsafe { ptr::read(&mut self.inner) };
+        mem::forget(self);
+
+        (inner, buf)
     }
 
     // Ensure this function does not get inlined into `write`, so that it
@@ -643,7 +647,7 @@ where
 {
     fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
         fmt.debug_struct("BufWriter")
-            .field("writer", &self.inner.as_ref().unwrap())
+            .field("writer", &self.inner)
             .field("buffer", &format_args!("{}/{}", self.buf.len(), self.buf.capacity()))
             .finish()
     }
@@ -663,7 +667,7 @@ impl<W: Write + Seek> Seek for BufWriter<W> {
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<W: Write> Drop for BufWriter<W> {
     fn drop(&mut self) {
-        if self.inner.is_some() && !self.panicked {
+        if !self.panicked {
             // dtors should not panic, so we ignore a failed flush
             let _r = self.flush_buf();
         }

library/std/src/io/buffered/mod.rs

@@ -133,7 +133,6 @@ impl<W> IntoInnerError<W> {
     ///
     /// # Example
     /// ```
-    /// #![feature(io_into_inner_error_parts)]
     /// use std::io::{BufWriter, ErrorKind, Write};
     ///
     /// let mut not_enough_space = [0u8; 10];
@@ -143,7 +142,7 @@ impl<W> IntoInnerError<W> {
     /// let err = into_inner_err.into_error();
     /// assert_eq!(err.kind(), ErrorKind::WriteZero);
     /// ```
-    #[unstable(feature = "io_into_inner_error_parts", issue = "79704")]
+    #[stable(feature = "io_into_inner_error_parts", since = "1.55.0")]
     pub fn into_error(self) -> Error {
         self.1
     }
@@ -156,7 +155,6 @@ impl<W> IntoInnerError<W> {
     ///
     /// # Example
     /// ```
-    /// #![feature(io_into_inner_error_parts)]
     /// use std::io::{BufWriter, ErrorKind, Write};
     ///
     /// let mut not_enough_space = [0u8; 10];
@@ -167,7 +165,7 @@ impl<W> IntoInnerError<W> {
     /// assert_eq!(err.kind(), ErrorKind::WriteZero);
     /// assert_eq!(recovered_writer.buffer(), b"t be actually written");
     /// ```
-    #[unstable(feature = "io_into_inner_error_parts", issue = "79704")]
+    #[stable(feature = "io_into_inner_error_parts", since = "1.55.0")]
     pub fn into_parts(self) -> (Error, W) {
         (self.1, self.0)
     }

src/bootstrap/compile.rs

@@ -3,7 +3,7 @@
 //!
 //! This module contains some of the real meat in the rustbuild build system
 //! which is where Cargo is used to compile the standard library, libtest, and
-//! compiler. This module is also responsible for assembling the sysroot as it
+//! the compiler. This module is also responsible for assembling the sysroot as it
 //! goes along from the output of the previous stage.
 
 use std::borrow::Cow;