Auto merge of #49460 - kennytm:rollup, r=kennytm

Rollup of 12 pull requests

- Successful merges: #49243, #49329, #49364, #49400, #49405, #49427, #49428, #49429, #49439, #49442, #49444, #49452
- Failed merges:

Author: bors

src/doc/unstable-book/src/library-features/string-retain.md

@@ -509,6 +509,31 @@ impl<T: Ord> BinaryHeap<T> {
         self.data.shrink_to_fit();
     }
 
+    /// Discards capacity with a lower bound.
+    ///
+    /// The capacity will remain at least as large as both the length
+    /// and the supplied value.
+    ///
+    /// Panics if the current capacity is smaller than the supplied
+    /// minimum capacity.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(shrink_to)]
+    /// use std::collections::BinaryHeap;
+    /// let mut heap: BinaryHeap<i32> = BinaryHeap::with_capacity(100);
+    ///
+    /// assert!(heap.capacity() >= 100);
+    /// heap.shrink_to(10);
+    /// assert!(heap.capacity() >= 10);
+    /// ```
+    #[inline]
+    #[unstable(feature = "shrink_to", reason = "new API", issue="0")]
+    pub fn shrink_to(&mut self, min_capacity: usize) {
+        self.data.shrink_to(min_capacity)
+    }
+
     /// Removes the greatest item from the binary heap and returns it, or `None` if it
     /// is empty.
     ///

src/liballoc/binary_heap.rs

@@ -1015,6 +1015,34 @@ impl String {
         self.vec.shrink_to_fit()
     }
 
+    /// Shrinks the capacity of this `String` with a lower bound.
+    ///
+    /// The capacity will remain at least as large as both the length
+    /// and the supplied value.
+    ///
+    /// Panics if the current capacity is smaller than the supplied
+    /// minimum capacity.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(shrink_to)]
+    /// let mut s = String::from("foo");
+    ///
+    /// s.reserve(100);
+    /// assert!(s.capacity() >= 100);
+    ///
+    /// s.shrink_to(10);
+    /// assert!(s.capacity() >= 10);
+    /// s.shrink_to(0);
+    /// assert!(s.capacity() >= 3);
+    /// ```
+    #[inline]
+    #[unstable(feature = "shrink_to", reason = "new API", issue="0")]
+    pub fn shrink_to(&mut self, min_capacity: usize) {
+        self.vec.shrink_to(min_capacity)
+    }
+
     /// Appends the given [`char`] to the end of this `String`.
     ///
     /// [`char`]: ../../std/primitive.char.html
@@ -1177,16 +1205,14 @@ impl String {
     /// # Examples
     ///
     /// ```
-    /// #![feature(string_retain)]
-    ///
     /// let mut s = String::from("f_o_ob_ar");
     ///
     /// s.retain(|c| c != '_');
     ///
     /// assert_eq!(s, "foobar");
     /// ```
     #[inline]
-    #[unstable(feature = "string_retain", issue = "43874")]
+    #[stable(feature = "string_retain", since = "1.26.0")]
     pub fn retain<F>(&mut self, mut f: F)
         where F: FnMut(char) -> bool
     {

src/liballoc/string.rs

@@ -66,7 +66,7 @@
 
 #![stable(feature = "rust1", since = "1.0.0")]
 
-use core::cmp::Ordering;
+use core::cmp::{self, Ordering};
 use core::fmt;
 use core::hash::{self, Hash};
 use core::intrinsics::{arith_offset, assume};
@@ -334,9 +334,10 @@ impl<T> Vec<T> {
     /// The vector will be able to hold exactly `capacity` elements without
     /// reallocating. If `capacity` is 0, the vector will not allocate.
     ///
-    /// It is important to note that this function does not specify the *length*
-    /// of the returned vector, but only the *capacity*. For an explanation of
-    /// the difference between length and capacity, see *[Capacity and reallocation]*.
+    /// It is important to note that although the returned vector has the
+    /// *capacity* specified, the vector will have a zero *length*. For an
+    /// explanation of the difference between length and capacity, see
+    /// *[Capacity and reallocation]*.
     ///
     /// [Capacity and reallocation]: #capacity-and-reallocation
     ///
@@ -586,6 +587,31 @@ impl<T> Vec<T> {
         self.buf.shrink_to_fit(self.len);
     }
 
+    /// Shrinks the capacity of the vector with a lower bound.
+    ///
+    /// The capacity will remain at least as large as both the length
+    /// and the supplied value.
+    ///
+    /// Panics if the current capacity is smaller than the supplied
+    /// minimum capacity.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(shrink_to)]
+    /// let mut vec = Vec::with_capacity(10);
+    /// vec.extend([1, 2, 3].iter().cloned());
+    /// assert_eq!(vec.capacity(), 10);
+    /// vec.shrink_to(4);
+    /// assert!(vec.capacity() >= 4);
+    /// vec.shrink_to(0);
+    /// assert!(vec.capacity() >= 3);
+    /// ```
+    #[unstable(feature = "shrink_to", reason = "new API", issue="0")]
+    pub fn shrink_to(&mut self, min_capacity: usize) {
+        self.buf.shrink_to_fit(cmp::max(self.len, min_capacity));
+    }
+
     /// Converts the vector into [`Box<[T]>`][owned slice].
     ///
     /// Note that this will drop any excess capacity.

src/liballoc/vec.rs

@@ -676,9 +676,42 @@ impl<T> VecDeque<T> {
     /// ```
     #[stable(feature = "deque_extras_15", since = "1.5.0")]
     pub fn shrink_to_fit(&mut self) {
+        self.shrink_to(0);
+    }
+
+    /// Shrinks the capacity of the `VecDeque` with a lower bound.
+    ///
+    /// The capacity will remain at least as large as both the length
+    /// and the supplied value.
+    ///
+    /// Panics if the current capacity is smaller than the supplied
+    /// minimum capacity.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(shrink_to)]
+    /// use std::collections::VecDeque;
+    ///
+    /// let mut buf = VecDeque::with_capacity(15);
+    /// buf.extend(0..4);
+    /// assert_eq!(buf.capacity(), 15);
+    /// buf.shrink_to(6);
+    /// assert!(buf.capacity() >= 6);
+    /// buf.shrink_to(0);
+    /// assert!(buf.capacity() >= 4);
+    /// ```
+    #[unstable(feature = "shrink_to", reason = "new API", issue="0")]
+    pub fn shrink_to(&mut self, min_capacity: usize) {
+        assert!(self.capacity() >= min_capacity, "Tried to shrink to a larger capacity");
+
         // +1 since the ringbuffer always leaves one space empty
         // len + 1 can't overflow for an existing, well-formed ringbuffer.
-        let target_cap = cmp::max(self.len() + 1, MINIMUM_CAPACITY + 1).next_power_of_two();
+        let target_cap = cmp::max(
+            cmp::max(min_capacity, self.len()) + 1,
+            MINIMUM_CAPACITY + 1
+        ).next_power_of_two();
+
         if target_cap < self.cap() {
             // There are three cases of interest:
             //   All elements are out of desired bounds

src/liballoc/vec_deque.rs

@@ -901,7 +901,9 @@ pub fn phase_2_configure_and_expand_inner<'a, F>(sess: &'a Session,
         Some(future) => {
             let prev_graph = time(sess, "blocked while dep-graph loading finishes", || {
                 future.open()
-                      .expect("Could not join with background dep_graph thread")
+                      .unwrap_or_else(|e| rustc_incremental::LoadResult::Error {
+                          message: format!("could not decode incremental cache: {:?}", e)
+                      })
                       .open(sess)
             });
             DepGraph::new(prev_graph)

src/librustc_const_eval/lib.rs

@@ -39,6 +39,7 @@ pub use assert_dep_graph::assert_dep_graph;
 pub use persist::dep_graph_tcx_init;
 pub use persist::load_dep_graph;
 pub use persist::load_query_result_cache;
+pub use persist::LoadResult;
 pub use persist::save_dep_graph;
 pub use persist::save_trans_partition;
 pub use persist::save_work_products;

src/librustc_driver/driver.rs

@@ -89,7 +89,8 @@ impl LoadResult<PreviousDepGraph> {
     pub fn open(self, sess: &Session) -> PreviousDepGraph {
         match self {
             LoadResult::Error { message } => {
-                sess.fatal(&message) /* never returns */
+                sess.warn(&message);
+                PreviousDepGraph::new(SerializedDepGraph::new())
             },
             LoadResult::DataOutOfDate => {
                 if let Err(err) = delete_all_session_dir_contents(sess) {

src/librustc_incremental/lib.rs

@@ -27,6 +27,7 @@ pub use self::fs::prepare_session_directory;
 pub use self::load::dep_graph_tcx_init;
 pub use self::load::load_dep_graph;
 pub use self::load::load_query_result_cache;
+pub use self::load::LoadResult;
 pub use self::save::save_dep_graph;
 pub use self::save::save_work_products;
 pub use self::work_product::save_trans_partition;

src/librustc_incremental/persist/load.rs

@@ -713,6 +713,7 @@ fn link_natively(sess: &Session,
         // linking executables as pie. Different versions of gcc seem to use
         // different quotes in the error message so don't check for them.
         if sess.target.target.options.linker_is_gnu &&
+           sess.linker_flavor() != LinkerFlavor::Ld &&
            (out.contains("unrecognized command line option") ||
             out.contains("unknown argument")) &&
            out.contains("-no-pie") &&
@@ -1008,8 +1009,9 @@ fn link_args(cmd: &mut Linker,
         } else {
             // recent versions of gcc can be configured to generate position
             // independent executables by default. We have to pass -no-pie to
-            // explicitly turn that off.
-            if sess.target.target.options.linker_is_gnu {
+            // explicitly turn that off. Not applicable to ld.
+            if sess.target.target.options.linker_is_gnu
+                && sess.linker_flavor() != LinkerFlavor::Ld {
                 cmd.no_position_independent_executable();
             }
         }