Auto merge of rust-lang#87413 - JohnTitor:rollup-dht22jk, r=JohnTitor

Rollup of 14 pull requests

Successful merges:

 - rust-lang#86410 (VecMap::get_value_matching should return just one element)
 - rust-lang#86790 (Document iteration order of `retain` functions)
 - rust-lang#87171 (Remove Option from BufWriter)
 - rust-lang#87175 (Stabilize `into_parts()` and `into_error()`)
 - rust-lang#87185 (Fix panics on Windows when the build was cancelled)
 - rust-lang#87191 (Package LLVM libs for the target rather than the build host)
 - rust-lang#87255 (better support for running libcore tests with Miri)
 - rust-lang#87266 (Add testcase for 87076)
 - rust-lang#87283 (Add `--codegen-backends=foo,bar` configure flag)
 - rust-lang#87322 (fix: clarify suggestion that `&T` must refer to `T: Sync` for `&T: Send`)
 - rust-lang#87358 (Fix `--dry-run` when download-ci-llvm is set)
 - rust-lang#87380 (Don't default to `submodules = true` unless the rust repo has a .git directory)
 - rust-lang#87398 (Add test for fonts used for module items)
 - rust-lang#87412 (Add missing article)

Failed merges:

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

Author: bors

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
     ///