Auto merge of #50611 - alexcrichton:rollup, r=alexcrichton

Rollup of 18 pull requests

Successful merges:

 - #49423 (Extend tests for RFC1598 (GAT))
 - #50010 (Give SliceIndex impls a test suite of girth befitting the implementation (and fix a UTF8 boundary check))
 - #50447 (Fix update-references for tests within subdirectories.)
 - #50514 (Pull in a wasm fix from LLVM upstream)
 - #50524 (Make DepGraph::previous_work_products immutable)
 - #50532 (Don't use Lock for heavily accessed CrateMetadata::cnum_map.)
 - #50538 ( Make CrateNum allocation more thread-safe. )
 - #50564 (Inline `Span` methods.)
 - #50565 (Use SmallVec for DepNodeIndex within dep_graph.)
 - #50569 (Allow for specifying a linker plugin for cross-language LTO)
 - #50572 (Clarify in the docs that `mul_add` is not always faster.)
 - #50574 (add fn `into_inner(self) -> (Idx, Idx)` to RangeInclusive (#49022))
 - #50575 (std: Avoid `ptr::copy` if unnecessary in `vec::Drain`)
 - #50588 (Move "See also" disambiguation links for primitive types to top)
 - #50590 (Fix tuple struct field spans)
 - #50591 (Restore RawVec::reserve* documentation)
 - #50598 (Remove unnecessary mutable borrow and resizing in DepGraph::serialize)
 - #50606 (Retry when downloading the Docker cache.)

Failed merges:

 - #50161 (added missing implementation hint)
 - #50558 (Remove all reference to DepGraph::work_products)

7 files changed, 261 insertions, 78 deletions

diff --git a/src/libcore/num/f32.rs b/src/libcore/num/f32.rs
index 672119eba7f..4a7dc13f0f2 100644
--- a/src/libcore/num/f32.rs
+++ b/src/libcore/num/f32.rs
@@ -11,9 +11,9 @@
 //! This module provides constants which are specific to the implementation
 //! of the `f32` floating point data type.
 //!
-//! Mathematically significant numbers are provided in the `consts` sub-module.
-//!
 //! *[See also the `f32` primitive type](../../std/primitive.f32.html).*
+//!
+//! Mathematically significant numbers are provided in the `consts` sub-module.
 
 #![stable(feature = "rust1", since = "1.0.0")]
 
diff --git a/src/libcore/num/f64.rs b/src/libcore/num/f64.rs
index 220b23a1e6a..801de5e87bd 100644
--- a/src/libcore/num/f64.rs
+++ b/src/libcore/num/f64.rs
@@ -11,9 +11,9 @@
 //! This module provides constants which are specific to the implementation
 //! of the `f64` floating point data type.
 //!
-//! Mathematically significant numbers are provided in the `consts` sub-module.
-//!
 //! *[See also the `f64` primitive type](../../std/primitive.f64.html).*
+//!
+//! Mathematically significant numbers are provided in the `consts` sub-module.
 
 #![stable(feature = "rust1", since = "1.0.0")]
 
diff --git a/src/libcore/ops/range.rs b/src/libcore/ops/range.rs
index b01a769eda7..697e6a3efde 100644
--- a/src/libcore/ops/range.rs
+++ b/src/libcore/ops/range.rs
@@ -411,6 +411,21 @@ impl<Idx> RangeInclusive<Idx> {
     pub fn end(&self) -> &Idx {
         &self.end
     }
+
+    /// Destructures the RangeInclusive into (lower bound, upper (inclusive) bound).
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(inclusive_range_methods)]
+    ///
+    /// assert_eq!((3..=5).into_inner(), (3, 5));
+    /// ```
+    #[unstable(feature = "inclusive_range_methods", issue = "49022")]
+    #[inline]
+    pub fn into_inner(self) -> (Idx, Idx) {
+        (self.start, self.end)
+    }
 }
 
 #[stable(feature = "inclusive_range", since = "1.26.0")]
diff --git a/src/libcore/slice/mod.rs b/src/libcore/slice/mod.rs
index 83e8a6e4b68..93ebc23ac0b 100644
--- a/src/libcore/slice/mod.rs
+++ b/src/libcore/slice/mod.rs
@@ -2262,6 +2262,12 @@ fn slice_index_order_fail(index: usize, end: usize) -> ! {
     panic!("slice index starts at {} but ends at {}", index, end);
 }
 
+#[inline(never)]
+#[cold]
+fn slice_index_overflow_fail() -> ! {
+    panic!("attempted to index slice up to maximum usize");
+}
+
 /// A helper trait used for indexing operations.
 #[unstable(feature = "slice_get_slice", issue = "35729")]
 #[rustc_on_unimplemented = "slice indices are of type `usize` or ranges of `usize`"]
@@ -2538,15 +2544,13 @@ impl<T> SliceIndex<[T]> for ops::RangeInclusive<usize> {
 
     #[inline]
     fn index(self, slice: &[T]) -> &[T] {
-        assert!(self.end != usize::max_value(),
-            "attempted to index slice up to maximum usize");
+        if self.end == usize::max_value() { slice_index_overflow_fail(); }
         (self.start..self.end + 1).index(slice)
     }
 
     #[inline]
     fn index_mut(self, slice: &mut [T]) -> &mut [T] {
-        assert!(self.end != usize::max_value(),
-            "attempted to index slice up to maximum usize");
+        if self.end == usize::max_value() { slice_index_overflow_fail(); }
         (self.start..self.end + 1).index_mut(slice)
     }
 }
diff --git a/src/libcore/str/mod.rs b/src/libcore/str/mod.rs
index b39d9feb35b..df7b2f25a86 100644
--- a/src/libcore/str/mod.rs
+++ b/src/libcore/str/mod.rs
@@ -1849,6 +1849,12 @@ mod traits {
         }
     }
 
+    #[inline(never)]
+    #[cold]
+    fn str_index_overflow_fail() -> ! {
+        panic!("attempted to index str up to maximum usize");
+    }
+
     #[stable(feature = "str_checked_slicing", since = "1.20.0")]
     impl SliceIndex<str> for ops::RangeFull {
         type Output = str;
@@ -2029,19 +2035,13 @@ mod traits {
         type Output = str;
         #[inline]
         fn get(self, slice: &str) -> Option<&Self::Output> {
-            if let Some(end) = self.end.checked_add(1) {
-                (self.start..end).get(slice)
-            } else {
-                None
-            }
+            if self.end == usize::max_value() { None }
+            else { (self.start..self.end+1).get(slice) }
         }
         #[inline]
         fn get_mut(self, slice: &mut str) -> Option<&mut Self::Output> {
-            if let Some(end) = self.end.checked_add(1) {
-                (self.start..end).get_mut(slice)
-            } else {
-                None
-            }
+            if self.end == usize::max_value() { None }
+            else { (self.start..self.end+1).get_mut(slice) }
         }
         #[inline]
         unsafe fn get_unchecked(self, slice: &str) -> &Self::Output {
@@ -2053,14 +2053,12 @@ mod traits {
         }
         #[inline]
         fn index(self, slice: &str) -> &Self::Output {
-            assert!(self.end != usize::max_value(),
-                "attempted to index str up to maximum usize");
+            if self.end == usize::max_value() { str_index_overflow_fail(); }
             (self.start..self.end+1).index(slice)
         }
         #[inline]
         fn index_mut(self, slice: &mut str) -> &mut Self::Output {
-            assert!(self.end != usize::max_value(),
-                "attempted to index str up to maximum usize");
+            if self.end == usize::max_value() { str_index_overflow_fail(); }
             (self.start..self.end+1).index_mut(slice)
         }
     }
@@ -2072,40 +2070,30 @@ mod traits {
         type Output = str;
         #[inline]
         fn get(self, slice: &str) -> Option<&Self::Output> {
-            if self.end < usize::max_value() && slice.is_char_boundary(self.end + 1) {
-                Some(unsafe { self.get_unchecked(slice) })
-            } else {
-                None
-            }
+            if self.end == usize::max_value() { None }
+            else { (..self.end+1).get(slice) }
         }
         #[inline]
         fn get_mut(self, slice: &mut str) -> Option<&mut Self::Output> {
-            if self.end < usize::max_value() && slice.is_char_boundary(self.end + 1) {
-                Some(unsafe { self.get_unchecked_mut(slice) })
-            } else {
-                None
-            }
+            if self.end == usize::max_value() { None }
+            else { (..self.end+1).get_mut(slice) }
         }
         #[inline]
         unsafe fn get_unchecked(self, slice: &str) -> &Self::Output {
-            let ptr = slice.as_ptr();
-            super::from_utf8_unchecked(slice::from_raw_parts(ptr, self.end + 1))
+            (..self.end+1).get_unchecked(slice)
         }
         #[inline]
         unsafe fn get_unchecked_mut(self, slice: &mut str) -> &mut Self::Output {
-            let ptr = slice.as_ptr();
-            super::from_utf8_unchecked_mut(slice::from_raw_parts_mut(ptr as *mut u8, self.end + 1))
+            (..self.end+1).get_unchecked_mut(slice)
         }
         #[inline]
         fn index(self, slice: &str) -> &Self::Output {
-            assert!(self.end != usize::max_value(),
-                "attempted to index str up to maximum usize");
+            if self.end == usize::max_value() { str_index_overflow_fail(); }
             (..self.end+1).index(slice)
         }
         #[inline]
         fn index_mut(self, slice: &mut str) -> &mut Self::Output {
-            assert!(self.end != usize::max_value(),
-                "attempted to index str up to maximum usize");
+            if self.end == usize::max_value() { str_index_overflow_fail(); }
             (..self.end+1).index_mut(slice)
         }
     }
diff --git a/src/libcore/tests/slice.rs b/src/libcore/tests/slice.rs
index c81e5e97cbb..19b5c86c474 100644
--- a/src/libcore/tests/slice.rs
+++ b/src/libcore/tests/slice.rs
@@ -376,48 +376,224 @@ fn test_windows_zip() {
     assert_eq!(res, [14, 18, 22, 26]);
 }
 
-#[test]
-fn get_range() {
-    let v: &[i32] = &[0, 1, 2, 3, 4, 5];
-    assert_eq!(v.get(..), Some(&[0, 1, 2, 3, 4, 5][..]));
-    assert_eq!(v.get(..2), Some(&[0, 1][..]));
-    assert_eq!(v.get(2..), Some(&[2, 3, 4, 5][..]));
-    assert_eq!(v.get(1..4), Some(&[1, 2, 3][..]));
-    assert_eq!(v.get(7..), None);
-    assert_eq!(v.get(7..10), None);
-}
+// The current implementation of SliceIndex fails to handle methods
+// orthogonally from range types; therefore, it is worth testing
+// all of the indexing operations on each input.
+mod slice_index {
+    // This checks all six indexing methods, given an input range that
+    // should succeed. (it is NOT suitable for testing invalid inputs)
+    macro_rules! assert_range_eq {
+        ($arr:expr, $range:expr, $expected:expr)
+        => {
+            let mut arr = $arr;
+            let mut expected = $expected;
+            {
+                let s: &[_] = &arr;
+                let expected: &[_] = &expected;
+
+                assert_eq!(&s[$range], expected, "(in assertion for: index)");
+                assert_eq!(s.get($range), Some(expected), "(in assertion for: get)");
+                unsafe {
+                    assert_eq!(
+                        s.get_unchecked($range), expected,
+                        "(in assertion for: get_unchecked)",
+                    );
+                }
+            }
+            {
+                let s: &mut [_] = &mut arr;
+                let expected: &mut [_] = &mut expected;
+
+                assert_eq!(
+                    &mut s[$range], expected,
+                    "(in assertion for: index_mut)",
+                );
+                assert_eq!(
+                    s.get_mut($range), Some(&mut expected[..]),
+                    "(in assertion for: get_mut)",
+                );
+                unsafe {
+                    assert_eq!(
+                        s.get_unchecked_mut($range), expected,
+                        "(in assertion for: get_unchecked_mut)",
+                    );
+                }
+            }
+        }
+    }
 
-#[test]
-fn get_mut_range() {
-    let v: &mut [i32] = &mut [0, 1, 2, 3, 4, 5];
-    assert_eq!(v.get_mut(..), Some(&mut [0, 1, 2, 3, 4, 5][..]));
-    assert_eq!(v.get_mut(..2), Some(&mut [0, 1][..]));
-    assert_eq!(v.get_mut(2..), Some(&mut [2, 3, 4, 5][..]));
-    assert_eq!(v.get_mut(1..4), Some(&mut [1, 2, 3][..]));
-    assert_eq!(v.get_mut(7..), None);
-    assert_eq!(v.get_mut(7..10), None);
-}
+    // Make sure the macro can actually detect bugs,
+    // because if it can't, then what are we even doing here?
+    //
+    // (Be aware this only demonstrates the ability to detect bugs
+    //  in the FIRST method that panics, as the macro is not designed
+    //  to be used in `should_panic`)
+    #[test]
+    #[should_panic(expected = "out of range")]
+    fn assert_range_eq_can_fail_by_panic() {
+        assert_range_eq!([0, 1, 2], 0..5, [0, 1, 2]);
+    }
 
-#[test]
-fn get_unchecked_range() {
-    unsafe {
-        let v: &[i32] = &[0, 1, 2, 3, 4, 5];
-        assert_eq!(v.get_unchecked(..), &[0, 1, 2, 3, 4, 5][..]);
-        assert_eq!(v.get_unchecked(..2), &[0, 1][..]);
-        assert_eq!(v.get_unchecked(2..), &[2, 3, 4, 5][..]);
-        assert_eq!(v.get_unchecked(1..4), &[1, 2, 3][..]);
+    // (Be aware this only demonstrates the ability to detect bugs
+    //  in the FIRST method it calls, as the macro is not designed
+    //  to be used in `should_panic`)
+    #[test]
+    #[should_panic(expected = "==")]
+    fn assert_range_eq_can_fail_by_inequality() {
+        assert_range_eq!([0, 1, 2], 0..2, [0, 1, 2]);
     }
-}
 
-#[test]
-fn get_unchecked_mut_range() {
-    unsafe {
-        let v: &mut [i32] = &mut [0, 1, 2, 3, 4, 5];
-        assert_eq!(v.get_unchecked_mut(..), &mut [0, 1, 2, 3, 4, 5][..]);
-        assert_eq!(v.get_unchecked_mut(..2), &mut [0, 1][..]);
-        assert_eq!(v.get_unchecked_mut(2..), &mut[2, 3, 4, 5][..]);
-        assert_eq!(v.get_unchecked_mut(1..4), &mut [1, 2, 3][..]);
+    // Test cases for bad index operations.
+    //
+    // This generates `should_panic` test cases for Index/IndexMut
+    // and `None` test cases for get/get_mut.
+    macro_rules! panic_cases {
+        ($(
+            // each test case needs a unique name to namespace the tests
+            in mod $case_name:ident {
+                data: $data:expr;
+
+                // optional:
+                //
+                // one or more similar inputs for which data[input] succeeds,
+                // and the corresponding output as an array.  This helps validate
+                // "critical points" where an input range straddles the boundary
+                // between valid and invalid.
+                // (such as the input `len..len`, which is just barely valid)
+                $(
+                    good: data[$good:expr] == $output:expr;
+                )*
+
+                bad: data[$bad:expr];
+                message: $expect_msg:expr;
+            }
+        )*) => {$(
+            mod $case_name {
+                #[test]
+                fn pass() {
+                    let mut v = $data;
+
+                    $( assert_range_eq!($data, $good, $output); )*
+
+                    {
+                        let v: &[_] = &v;
+                        assert_eq!(v.get($bad), None, "(in None assertion for get)");
+                    }
+
+                    {
+                        let v: &mut [_] = &mut v;
+                        assert_eq!(v.get_mut($bad), None, "(in None assertion for get_mut)");
+                    }
+                }
+
+                #[test]
+                #[should_panic(expected = $expect_msg)]
+                fn index_fail() {
+                    let v = $data;
+                    let v: &[_] = &v;
+                    let _v = &v[$bad];
+                }
+
+                #[test]
+                #[should_panic(expected = $expect_msg)]
+                fn index_mut_fail() {
+                    let mut v = $data;
+                    let v: &mut [_] = &mut v;
+                    let _v = &mut v[$bad];
+                }
+            }
+        )*};
     }
+
+    #[test]
+    fn simple() {
+        let v = [0, 1, 2, 3, 4, 5];
+
+        assert_range_eq!(v, .., [0, 1, 2, 3, 4, 5]);
+        assert_range_eq!(v, ..2, [0, 1]);
+        assert_range_eq!(v, ..=1, [0, 1]);
+        assert_range_eq!(v, 2.., [2, 3, 4, 5]);
+        assert_range_eq!(v, 1..4, [1, 2, 3]);
+        assert_range_eq!(v, 1..=3, [1, 2, 3]);
+    }
+
+    panic_cases! {
+        in mod rangefrom_len {
+            data: [0, 1, 2, 3, 4, 5];
+
+            good: data[6..] == [];
+            bad: data[7..];
+            message: "but ends at"; // perhaps not ideal
+        }
+
+        in mod rangeto_len {
+            data: [0, 1, 2, 3, 4, 5];
+
+            good: data[..6] == [0, 1, 2, 3, 4, 5];
+            bad: data[..7];
+            message: "out of range";
+        }
+
+        in mod rangetoinclusive_len {
+            data: [0, 1, 2, 3, 4, 5];
+
+            good: data[..=5] == [0, 1, 2, 3, 4, 5];
+            bad: data[..=6];
+            message: "out of range";
+        }
+
+        in mod range_len_len {
+            data: [0, 1, 2, 3, 4, 5];
+
+            good: data[6..6] == [];
+            bad: data[7..7];
+            message: "out of range";
+        }
+
+        in mod rangeinclusive_len_len {
+            data: [0, 1, 2, 3, 4, 5];
+
+            good: data[6..=5] == [];
+            bad: data[7..=6];
+            message: "out of range";
+        }
+    }
+
+    panic_cases! {
+        in mod range_neg_width {
+            data: [0, 1, 2, 3, 4, 5];
+
+            good: data[4..4] == [];
+            bad: data[4..3];
+            message: "but ends at";
+        }
+
+        in mod rangeinclusive_neg_width {
+            data: [0, 1, 2, 3, 4, 5];
+
+            good: data[4..=3] == [];
+            bad: data[4..=2];
+            message: "but ends at";
+        }
+    }
+
+    panic_cases! {
+        in mod rangeinclusive_overflow {
+            data: [0, 1];
+
+            // note: using 0 specifically ensures that the result of overflowing is 0..0,
+            //       so that `get` doesn't simply return None for the wrong reason.
+            bad: data[0 ..= ::std::usize::MAX];
+            message: "maximum usize";
+        }
+
+        in mod rangetoinclusive_overflow {
+            data: [0, 1];
+
+            bad: data[..= ::std::usize::MAX];
+            message: "maximum usize";
+        }
+    } // panic_cases!
 }
 
 #[test]
diff --git a/src/libcore/tests/str.rs b/src/libcore/tests/str.rs
index 08daafccc54..343c9596c53 100644
--- a/src/libcore/tests/str.rs
+++ b/src/libcore/tests/str.rs
@@ -8,4 +8,4 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-// All `str` tests live in collectionstests::str
+// All `str` tests live in liballoc/tests