diff --git a/config.toml.example b/config.toml.example
index c0be7dded17bc..2fa613755d64c 100644
--- a/config.toml.example
+++ b/config.toml.example
@@ -378,7 +378,7 @@
 # nightly features
 #channel = "dev"
 
-# The root location of the MUSL installation directory.
+# The root location of the musl installation directory.
 #musl-root = "..."
 
 # By default the `rustc` executable is built with `-Wl,-rpath` flags on Unix
@@ -521,12 +521,15 @@
 # only use static libraries. If unset, the target's default linkage is used.
 #crt-static = false
 
-# The root location of the MUSL installation directory. The library directory
+# The root location of the musl installation directory. The library directory
 # will also need to contain libunwind.a for an unwinding implementation. Note
-# that this option only makes sense for MUSL targets that produce statically
+# that this option only makes sense for musl targets that produce statically
 # linked binaries
 #musl-root = "..."
 
+# The full path to the musl libdir.
+#musl-libdir = musl-root/lib
+
 # The root location of the `wasm32-wasi` sysroot.
 #wasi-root = "..."
 
diff --git a/src/bootstrap/bootstrap.py b/src/bootstrap/bootstrap.py
index 82a755c7892b1..1949d70e5deea 100644
--- a/src/bootstrap/bootstrap.py
+++ b/src/bootstrap/bootstrap.py
@@ -184,6 +184,7 @@ def default_build_triple():
     ostype = require(["uname", "-s"], exit=required)
     cputype = require(['uname', '-m'], exit=required)
 
+    # If we do not have `uname`, assume Windows.
     if ostype is None or cputype is None:
         return 'x86_64-pc-windows-msvc'
 
@@ -236,6 +237,11 @@ def default_build_triple():
         if ostype.endswith('WOW64'):
             cputype = 'x86_64'
         ostype = 'pc-windows-gnu'
+    elif sys.platform == 'win32':
+        # Some Windows platforms might have a `uname` command that returns a
+        # non-standard string (e.g. gnuwin32 tools returns `windows32`). In
+        # these cases, fall back to using sys.platform.
+        return 'x86_64-pc-windows-msvc'
     else:
         err = "unknown OS type: {}".format(ostype)
         sys.exit(err)
diff --git a/src/bootstrap/compile.rs b/src/bootstrap/compile.rs
index 0208dc8ba5eb6..8e755756865b2 100644
--- a/src/bootstrap/compile.rs
+++ b/src/bootstrap/compile.rs
@@ -190,7 +190,7 @@ fn copy_self_contained_objects(
     // To do that we have to distribute musl startup objects as a part of Rust toolchain
     // and link with them manually in the self-contained mode.
     if target.contains("musl") {
-        let srcdir = builder.musl_root(target).unwrap().join("lib");
+        let srcdir = builder.musl_libdir(target).unwrap();
         for &obj in &["crt1.o", "Scrt1.o", "rcrt1.o", "crti.o", "crtn.o"] {
             copy_and_stamp(
                 builder,
@@ -279,8 +279,8 @@ pub fn std_cargo(builder: &Builder<'_>, target: Interned<String>, stage: u32, ca
         // Help the libc crate compile by assisting it in finding various
         // sysroot native libraries.
         if target.contains("musl") {
-            if let Some(p) = builder.musl_root(target) {
-                let root = format!("native={}/lib", p.to_str().unwrap());
+            if let Some(p) = builder.musl_libdir(target) {
+                let root = format!("native={}", p.to_str().unwrap());
                 cargo.rustflag("-L").rustflag(&root);
             }
         }
diff --git a/src/bootstrap/config.rs b/src/bootstrap/config.rs
index 771f952abc013..ff545a6ddcf47 100644
--- a/src/bootstrap/config.rs
+++ b/src/bootstrap/config.rs
@@ -173,6 +173,7 @@ pub struct Target {
     pub ndk: Option<PathBuf>,
     pub crt_static: Option<bool>,
     pub musl_root: Option<PathBuf>,
+    pub musl_libdir: Option<PathBuf>,
     pub wasi_root: Option<PathBuf>,
     pub qemu_rootfs: Option<PathBuf>,
     pub no_std: bool,
@@ -363,6 +364,7 @@ struct TomlTarget {
     android_ndk: Option<String>,
     crt_static: Option<bool>,
     musl_root: Option<String>,
+    musl_libdir: Option<String>,
     wasi_root: Option<String>,
     qemu_rootfs: Option<String>,
     no_std: Option<bool>,
@@ -631,6 +633,7 @@ impl Config {
                 target.linker = cfg.linker.clone().map(PathBuf::from);
                 target.crt_static = cfg.crt_static;
                 target.musl_root = cfg.musl_root.clone().map(PathBuf::from);
+                target.musl_libdir = cfg.musl_libdir.clone().map(PathBuf::from);
                 target.wasi_root = cfg.wasi_root.clone().map(PathBuf::from);
                 target.qemu_rootfs = cfg.qemu_rootfs.clone().map(PathBuf::from);
 
diff --git a/src/bootstrap/lib.rs b/src/bootstrap/lib.rs
index 5728b9d24de99..b611af54565ac 100644
--- a/src/bootstrap/lib.rs
+++ b/src/bootstrap/lib.rs
@@ -888,6 +888,15 @@ impl Build {
             .map(|p| &**p)
     }
 
+    /// Returns the "musl libdir" for this `target`.
+    fn musl_libdir(&self, target: Interned<String>) -> Option<PathBuf> {
+        let t = self.config.target_config.get(&target)?;
+        if let libdir @ Some(_) = &t.musl_libdir {
+            return libdir.clone();
+        }
+        self.musl_root(target).map(|root| root.join("lib"))
+    }
+
     /// Returns the sysroot for the wasi target, if defined
     fn wasi_root(&self, target: Interned<String>) -> Option<&Path> {
         self.config.target_config.get(&target).and_then(|t| t.wasi_root.as_ref()).map(|p| &**p)
diff --git a/src/bootstrap/sanity.rs b/src/bootstrap/sanity.rs
index 74b47d0772837..3301d41cfeefa 100644
--- a/src/bootstrap/sanity.rs
+++ b/src/bootstrap/sanity.rs
@@ -199,10 +199,10 @@ pub fn check(build: &mut Build) {
                 let target = build.config.target_config.entry(target.clone()).or_default();
                 target.musl_root = Some("/usr".into());
             }
-            match build.musl_root(*target) {
-                Some(root) => {
-                    if fs::metadata(root.join("lib/libc.a")).is_err() {
-                        panic!("couldn't find libc.a in musl dir: {}", root.join("lib").display());
+            match build.musl_libdir(*target) {
+                Some(libdir) => {
+                    if fs::metadata(libdir.join("libc.a")).is_err() {
+                        panic!("couldn't find libc.a in musl libdir: {}", libdir.display());
                     }
                 }
                 None => panic!(
diff --git a/src/liballoc/collections/btree/map.rs b/src/liballoc/collections/btree/map.rs
index 34cacebe79636..bb9091a66594b 100644
--- a/src/liballoc/collections/btree/map.rs
+++ b/src/liballoc/collections/btree/map.rs
@@ -1396,6 +1396,14 @@ impl<'a, K: 'a, V: 'a> Iterator for Iter<'a, K, V> {
     fn last(mut self) -> Option<(&'a K, &'a V)> {
         self.next_back()
     }
+
+    fn min(mut self) -> Option<(&'a K, &'a V)> {
+        self.next()
+    }
+
+    fn max(mut self) -> Option<(&'a K, &'a V)> {
+        self.next_back()
+    }
 }
 
 #[stable(feature = "fused", since = "1.26.0")]
@@ -1458,6 +1466,14 @@ impl<'a, K: 'a, V: 'a> Iterator for IterMut<'a, K, V> {
     fn last(mut self) -> Option<(&'a K, &'a mut V)> {
         self.next_back()
     }
+
+    fn min(mut self) -> Option<(&'a K, &'a mut V)> {
+        self.next()
+    }
+
+    fn max(mut self) -> Option<(&'a K, &'a mut V)> {
+        self.next_back()
+    }
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
@@ -1595,6 +1611,14 @@ impl<'a, K, V> Iterator for Keys<'a, K, V> {
     fn last(mut self) -> Option<&'a K> {
         self.next_back()
     }
+
+    fn min(mut self) -> Option<&'a K> {
+        self.next()
+    }
+
+    fn max(mut self) -> Option<&'a K> {
+        self.next_back()
+    }
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
@@ -1768,6 +1792,14 @@ impl<'a, K, V> Iterator for Range<'a, K, V> {
     fn last(mut self) -> Option<(&'a K, &'a V)> {
         self.next_back()
     }
+
+    fn min(mut self) -> Option<(&'a K, &'a V)> {
+        self.next()
+    }
+
+    fn max(mut self) -> Option<(&'a K, &'a V)> {
+        self.next_back()
+    }
 }
 
 #[stable(feature = "map_values_mut", since = "1.10.0")]
@@ -1853,6 +1885,14 @@ impl<'a, K, V> Iterator for RangeMut<'a, K, V> {
     fn last(mut self) -> Option<(&'a K, &'a mut V)> {
         self.next_back()
     }
+
+    fn min(mut self) -> Option<(&'a K, &'a mut V)> {
+        self.next()
+    }
+
+    fn max(mut self) -> Option<(&'a K, &'a mut V)> {
+        self.next_back()
+    }
 }
 
 impl<'a, K, V> RangeMut<'a, K, V> {
diff --git a/src/liballoc/collections/btree/set.rs b/src/liballoc/collections/btree/set.rs
index 525ef38c32fa2..d8959966fe5ad 100644
--- a/src/liballoc/collections/btree/set.rs
+++ b/src/liballoc/collections/btree/set.rs
@@ -1291,12 +1291,22 @@ impl<'a, T> Iterator for Iter<'a, T> {
     fn next(&mut self) -> Option<&'a T> {
         self.iter.next()
     }
+
     fn size_hint(&self) -> (usize, Option<usize>) {
         self.iter.size_hint()
     }
+
     fn last(mut self) -> Option<&'a T> {
         self.next_back()
     }
+
+    fn min(mut self) -> Option<&'a T> {
+        self.next()
+    }
+
+    fn max(mut self) -> Option<&'a T> {
+        self.next_back()
+    }
 }
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<'a, T> DoubleEndedIterator for Iter<'a, T> {
@@ -1321,6 +1331,7 @@ impl<T> Iterator for IntoIter<T> {
     fn next(&mut self) -> Option<T> {
         self.iter.next().map(|(k, _)| k)
     }
+
     fn size_hint(&self) -> (usize, Option<usize>) {
         self.iter.size_hint()
     }
@@ -1359,6 +1370,14 @@ impl<'a, T> Iterator for Range<'a, T> {
     fn last(mut self) -> Option<&'a T> {
         self.next_back()
     }
+
+    fn min(mut self) -> Option<&'a T> {
+        self.next()
+    }
+
+    fn max(mut self) -> Option<&'a T> {
+        self.next_back()
+    }
 }
 
 #[stable(feature = "btree_range", since = "1.17.0")]
@@ -1429,6 +1448,10 @@ impl<'a, T: Ord> Iterator for Difference<'a, T> {
         };
         (self_len.saturating_sub(other_len), Some(self_len))
     }
+
+    fn min(mut self) -> Option<&'a T> {
+        self.next()
+    }
 }
 
 #[stable(feature = "fused", since = "1.26.0")]
@@ -1460,6 +1483,10 @@ impl<'a, T: Ord> Iterator for SymmetricDifference<'a, T> {
         // the number of elements to less than half the range of usize.
         (0, Some(a_len + b_len))
     }
+
+    fn min(mut self) -> Option<&'a T> {
+        self.next()
+    }
 }
 
 #[stable(feature = "fused", since = "1.26.0")]
@@ -1516,6 +1543,10 @@ impl<'a, T: Ord> Iterator for Intersection<'a, T> {
             IntersectionInner::Answer(Some(_)) => (1, Some(1)),
         }
     }
+
+    fn min(mut self) -> Option<&'a T> {
+        self.next()
+    }
 }
 
 #[stable(feature = "fused", since = "1.26.0")]
@@ -1541,6 +1572,10 @@ impl<'a, T: Ord> Iterator for Union<'a, T> {
         // No checked_add - see SymmetricDifference::size_hint.
         (max(a_len, b_len), Some(a_len + b_len))
     }
+
+    fn min(mut self) -> Option<&'a T> {
+        self.next()
+    }
 }
 
 #[stable(feature = "fused", since = "1.26.0")]
diff --git a/src/liballoc/raw_vec/tests.rs b/src/liballoc/raw_vec/tests.rs
index 6418c4a9823f2..5408faa079c15 100644
--- a/src/liballoc/raw_vec/tests.rs
+++ b/src/liballoc/raw_vec/tests.rs
@@ -12,7 +12,6 @@ fn allocator_param() {
     //
     // Instead, this just checks that the `RawVec` methods do at
     // least go through the Allocator API when it reserves
-
     // storage.
 
     // A dumb allocator that consumes a fixed amount of fuel
diff --git a/src/liballoc/tests/btree/map.rs b/src/liballoc/tests/btree/map.rs
index 731a1b5f875b7..682d829d219f3 100644
--- a/src/liballoc/tests/btree/map.rs
+++ b/src/liballoc/tests/btree/map.rs
@@ -309,6 +309,41 @@ fn test_iter_mixed() {
     test(size, map.into_iter());
 }
 
+#[test]
+fn test_iter_min_max() {
+    let mut a = BTreeMap::new();
+    assert_eq!(a.iter().min(), None);
+    assert_eq!(a.iter().max(), None);
+    assert_eq!(a.iter_mut().min(), None);
+    assert_eq!(a.iter_mut().max(), None);
+    assert_eq!(a.range(..).min(), None);
+    assert_eq!(a.range(..).max(), None);
+    assert_eq!(a.range_mut(..).min(), None);
+    assert_eq!(a.range_mut(..).max(), None);
+    assert_eq!(a.keys().min(), None);
+    assert_eq!(a.keys().max(), None);
+    assert_eq!(a.values().min(), None);
+    assert_eq!(a.values().max(), None);
+    assert_eq!(a.values_mut().min(), None);
+    assert_eq!(a.values_mut().max(), None);
+    a.insert(1, 42);
+    a.insert(2, 24);
+    assert_eq!(a.iter().min(), Some((&1, &42)));
+    assert_eq!(a.iter().max(), Some((&2, &24)));
+    assert_eq!(a.iter_mut().min(), Some((&1, &mut 42)));
+    assert_eq!(a.iter_mut().max(), Some((&2, &mut 24)));
+    assert_eq!(a.range(..).min(), Some((&1, &42)));
+    assert_eq!(a.range(..).max(), Some((&2, &24)));
+    assert_eq!(a.range_mut(..).min(), Some((&1, &mut 42)));
+    assert_eq!(a.range_mut(..).max(), Some((&2, &mut 24)));
+    assert_eq!(a.keys().min(), Some(&1));
+    assert_eq!(a.keys().max(), Some(&2));
+    assert_eq!(a.values().min(), Some(&24));
+    assert_eq!(a.values().max(), Some(&42));
+    assert_eq!(a.values_mut().min(), Some(&mut 24));
+    assert_eq!(a.values_mut().max(), Some(&mut 42));
+}
+
 fn range_keys(map: &BTreeMap<i32, i32>, range: impl RangeBounds<i32>) -> Vec<i32> {
     map.range(range)
         .map(|(&k, &v)| {
diff --git a/src/liballoc/tests/btree/set.rs b/src/liballoc/tests/btree/set.rs
index 75251ca0d51e9..b6c34b7c6c346 100644
--- a/src/liballoc/tests/btree/set.rs
+++ b/src/liballoc/tests/btree/set.rs
@@ -33,6 +33,37 @@ fn test_hash() {
     assert_eq!(hash(&x), hash(&y));
 }
 
+#[test]
+fn test_iter_min_max() {
+    let mut a = BTreeSet::new();
+    assert_eq!(a.iter().min(), None);
+    assert_eq!(a.iter().max(), None);
+    assert_eq!(a.range(..).min(), None);
+    assert_eq!(a.range(..).max(), None);
+    assert_eq!(a.difference(&BTreeSet::new()).min(), None);
+    assert_eq!(a.difference(&BTreeSet::new()).max(), None);
+    assert_eq!(a.intersection(&a).min(), None);
+    assert_eq!(a.intersection(&a).max(), None);
+    assert_eq!(a.symmetric_difference(&BTreeSet::new()).min(), None);
+    assert_eq!(a.symmetric_difference(&BTreeSet::new()).max(), None);
+    assert_eq!(a.union(&a).min(), None);
+    assert_eq!(a.union(&a).max(), None);
+    a.insert(1);
+    a.insert(2);
+    assert_eq!(a.iter().min(), Some(&1));
+    assert_eq!(a.iter().max(), Some(&2));
+    assert_eq!(a.range(..).min(), Some(&1));
+    assert_eq!(a.range(..).max(), Some(&2));
+    assert_eq!(a.difference(&BTreeSet::new()).min(), Some(&1));
+    assert_eq!(a.difference(&BTreeSet::new()).max(), Some(&2));
+    assert_eq!(a.intersection(&a).min(), Some(&1));
+    assert_eq!(a.intersection(&a).max(), Some(&2));
+    assert_eq!(a.symmetric_difference(&BTreeSet::new()).min(), Some(&1));
+    assert_eq!(a.symmetric_difference(&BTreeSet::new()).max(), Some(&2));
+    assert_eq!(a.union(&a).min(), Some(&1));
+    assert_eq!(a.union(&a).max(), Some(&2));
+}
+
 fn check<F>(a: &[i32], b: &[i32], expected: &[i32], f: F)
 where
     F: FnOnce(&BTreeSet<i32>, &BTreeSet<i32>, &mut dyn FnMut(&i32) -> bool) -> bool,
diff --git a/src/libcore/mem/mod.rs b/src/libcore/mem/mod.rs
index 1bd7ae3a34ebb..46e6ea7cd1866 100644
--- a/src/libcore/mem/mod.rs
+++ b/src/libcore/mem/mod.rs
@@ -358,12 +358,13 @@ pub fn size_of_val<T: ?Sized>(val: &T) -> usize {
 ///     - an (unstable) [extern type], then this function is always safe to
 ///       call, but may panic or otherwise return the wrong value, as the
 ///       extern type's layout is not known. This is the same behavior as
-///       [`size_of_val`] on a reference to an extern type tail.
+///       [`size_of_val`] on a reference to a type with an extern type tail.
 ///     - otherwise, it is conservatively not allowed to call this function.
 ///
 /// [slice]: ../../std/primitive.slice.html
 /// [trait object]: ../../book/ch17-02-trait-objects.html
 /// [extern type]: ../../unstable-book/language-features/extern-types.html
+/// [`size_of_val`]: ../../core/mem/fn.size_of_val.html
 ///
 /// # Examples
 ///
@@ -492,12 +493,13 @@ pub fn align_of_val<T: ?Sized>(val: &T) -> usize {
 ///     - an (unstable) [extern type], then this function is always safe to
 ///       call, but may panic or otherwise return the wrong value, as the
 ///       extern type's layout is not known. This is the same behavior as
-///       [`align_of_val`] on a reference to an extern type tail.
+///       [`align_of_val`] on a reference to a type with an extern type tail.
 ///     - otherwise, it is conservatively not allowed to call this function.
 ///
 /// [slice]: ../../std/primitive.slice.html
 /// [trait object]: ../../book/ch17-02-trait-objects.html
 /// [extern type]: ../../unstable-book/language-features/extern-types.html
+/// [`align_of_val`]: ../../core/mem/fn.align_of_val.html
 ///
 /// # Examples
 ///
diff --git a/src/librustc_mir/transform/const_prop.rs b/src/librustc_mir/transform/const_prop.rs
index eb614170baae5..c7125a35165cf 100644
--- a/src/librustc_mir/transform/const_prop.rs
+++ b/src/librustc_mir/transform/const_prop.rs
@@ -350,14 +350,20 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> {
     }
 
     fn get_const(&self, place: Place<'tcx>) -> Option<OpTy<'tcx>> {
-        let op = self.ecx.eval_place_to_op(place, None).ok();
+        let op = match self.ecx.eval_place_to_op(place, None) {
+            Ok(op) => op,
+            Err(e) => {
+                trace!("get_const failed: {}", e);
+                return None;
+            }
+        };
 
         // Try to read the local as an immediate so that if it is representable as a scalar, we can
         // handle it as such, but otherwise, just return the value as is.
-        match op.map(|ret| self.ecx.try_read_immediate(ret)) {
-            Some(Ok(Ok(imm))) => Some(imm.into()),
+        Some(match self.ecx.try_read_immediate(op) {
+            Ok(Ok(imm)) => imm.into(),
             _ => op,
-        }
+        })
     }
 
     /// Remove `local` from the pool of `Locals`. Allows writing to them,
@@ -857,8 +863,9 @@ impl<'mir, 'tcx> MutVisitor<'tcx> for ConstPropagator<'mir, 'tcx> {
             if let Ok(place_layout) = self.tcx.layout_of(self.param_env.and(place_ty)) {
                 let can_const_prop = self.can_const_prop[place.local];
                 if let Some(()) = self.const_prop(rval, place_layout, source_info, place) {
-                    // This will return None for variables that are from other blocks,
-                    // so it should be okay to propagate from here on down.
+                    // This will return None if the above `const_prop` invocation only "wrote" a
+                    // type whose creation requires no write. E.g. a generator whose initial state
+                    // consists solely of uninitialized memory (so it doesn't capture any locals).
                     if let Some(value) = self.get_const(place) {
                         if self.should_const_prop(value) {
                             trace!("replacing {:?} with {:?}", rval, value);
diff --git a/src/libstd/keyword_docs.rs b/src/libstd/keyword_docs.rs
index f987eb67ea5f2..d972cf6db18cf 100644
--- a/src/libstd/keyword_docs.rs
+++ b/src/libstd/keyword_docs.rs
@@ -1217,11 +1217,66 @@ mod self_keyword {}
 /// The implementing type within a [`trait`] or [`impl`] block, or the current type within a type
 /// definition.
 ///
-/// The documentation for this keyword is [not yet complete]. Pull requests welcome!
+/// Within a type definition:
+///
+/// ```
+/// # #![allow(dead_code)]
+/// struct Node {
+///     elem: i32,
+///     // `Self` is a `Node` here.
+///     next: Option<Box<Self>>,
+/// }
+/// ```
+///
+/// In an [`impl`] block:
+///
+/// ```
+/// struct Foo(i32);
+///
+/// impl Foo {
+///     fn new() -> Self {
+///         Self(0)
+///     }
+/// }
+///
+/// assert_eq!(Foo::new().0, Foo(0).0);
+/// ```
+///
+/// Generic parameters are implicit with `Self`:
+///
+/// ```
+/// # #![allow(dead_code)]
+/// struct Wrap<T> {
+///     elem: T,
+/// }
+///
+/// impl<T> Wrap<T> {
+///     fn new(elem: T) -> Self {
+///         Self { elem }
+///     }
+/// }
+/// ```
+///
+/// In a [`trait`] definition and related [`impl`] block:
+///
+/// ```
+/// trait Example {
+///     fn example() -> Self;
+/// }
+///
+/// struct Foo(i32);
+///
+/// impl Example for Foo {
+///     fn example() -> Self {
+///         Self(42)
+///     }
+/// }
+///
+/// assert_eq!(Foo::example().0, Foo(42).0);
+/// ```
 ///
 /// [`impl`]: keyword.impl.html
 /// [`trait`]: keyword.trait.html
-/// [not yet complete]: https://github.com/rust-lang/rust/issues/34601
 mod self_upper_keyword {}
 
 #[doc(keyword = "static")]
@@ -1345,10 +1400,26 @@ mod struct_keyword {}
 //
 /// The parent of the current [module].
 ///
-/// The documentation for this keyword is [not yet complete]. Pull requests welcome!
+/// ```rust
+/// # #![allow(dead_code)]
+/// # fn main() {}
+/// mod a {
+///     pub fn foo() {}
+/// }
+/// mod b {
+///     pub fn foo() {
+///         super::a::foo(); // call a's foo function
+///     }
+/// }
+/// ```
+///
+/// It is also possible to use `super` multiple times: `super::super::foo`,
+/// going up the ancestor chain.
+///
+/// See the [Reference] for more information.
 ///
 /// [module]: ../reference/items/modules.html
-/// [not yet complete]: https://github.com/rust-lang/rust/issues/34601
+/// [Reference]: ../reference/paths.html#super
 mod super_keyword {}
 
 #[doc(keyword = "trait")]