Auto merge of rust-lang#83308 - Dylan-DPC:rollup-p2j6sy8, r=Dylan-DPC

Rollup of 8 pull requests

Successful merges:

 - rust-lang#79986 (Only build help popup when it's really needed)
 - rust-lang#82570 (Add `as_str` method for split whitespace str iterators)
 - rust-lang#83244 (Fix overflowing length in Vec<ZST> to VecDeque)
 - rust-lang#83254 (Include output stream in `panic!()` documentation)
 - rust-lang#83269 (Revert the second deprecation of collections::Bound)
 - rust-lang#83277 (Mark early otherwise optimization unsound)
 - rust-lang#83285 (Update LLVM to bring in SIMD updates for WebAssembly)
 - rust-lang#83297 (Do not ICE on ty::Error as an error must already have been reported)

Failed merges:

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

Author: bors

compiler/rustc_middle/src/ty/relate.rs

@@ -10,6 +10,7 @@ use crate::ty::subst::{GenericArg, GenericArgKind, SubstsRef};
 use crate::ty::{self, Ty, TyCtxt, TypeFoldable};
 use rustc_hir as ast;
 use rustc_hir::def_id::DefId;
+use rustc_span::DUMMY_SP;
 use rustc_target::spec::abi;
 use std::iter;
 
@@ -499,11 +500,14 @@ pub fn super_relate_consts<R: TypeRelation<'tcx>>(
 
     // FIXME(oli-obk): once const generics can have generic types, this assertion
     // will likely get triggered. Move to `normalize_erasing_regions` at that point.
-    assert_eq!(
-        tcx.erase_regions(a.ty),
-        tcx.erase_regions(b.ty),
-        "cannot relate constants of different types"
-    );
+    let a_ty = tcx.erase_regions(a.ty);
+    let b_ty = tcx.erase_regions(b.ty);
+    if a_ty != b_ty {
+        relation.tcx().sess.delay_span_bug(
+            DUMMY_SP,
+            &format!("cannot relate constants of different types: {} != {}", a_ty, b_ty),
+        );
+    }
 
     let eagerly_eval = |x: &'tcx ty::Const<'tcx>| x.eval(tcx, relation.param_env());
     let a = eagerly_eval(a);

compiler/rustc_mir/src/transform/early_otherwise_branch.rs

@@ -26,6 +26,11 @@ pub struct EarlyOtherwiseBranch;
 
 impl<'tcx> MirPass<'tcx> for EarlyOtherwiseBranch {
     fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
+        //  FIXME(#78496)
+        if !tcx.sess.opts.debugging_opts.unsound_mir_opts {
+            return;
+        }
+
         if tcx.sess.mir_opt_level() < 3 {
             return;
         }

library/alloc/src/collections/vec_deque/mod.rs

@@ -2783,27 +2783,26 @@ impl<T> From<Vec<T>> for VecDeque<T> {
     /// This avoids reallocating where possible, but the conditions for that are
     /// strict, and subject to change, and so shouldn't be relied upon unless the
     /// `Vec<T>` came from `From<VecDeque<T>>` and hasn't been reallocated.
-    fn from(other: Vec<T>) -> Self {
-        unsafe {
-            let mut other = ManuallyDrop::new(other);
-            let other_buf = other.as_mut_ptr();
-            let mut buf = RawVec::from_raw_parts(other_buf, other.capacity());
-            let len = other.len();
-
-            // We need to extend the buf if it's not a power of two, too small
-            // or doesn't have at least one free space.
-            // We check if `T` is a ZST in the first condition,
-            // because `usize::MAX` (the capacity returned by `capacity()` for ZST)
-            // is not a power of two and thus it'll always try
-            // to reserve more memory which will panic for ZST (rust-lang/rust#78532)
-            if (!buf.capacity().is_power_of_two() && mem::size_of::<T>() != 0)
-                || (buf.capacity() < (MINIMUM_CAPACITY + 1))
-                || (buf.capacity() == len)
-            {
-                let cap = cmp::max(buf.capacity() + 1, MINIMUM_CAPACITY + 1).next_power_of_two();
-                buf.reserve_exact(len, cap - len);
+    fn from(mut other: Vec<T>) -> Self {
+        let len = other.len();
+        if mem::size_of::<T>() == 0 {
+            // There's no actual allocation for ZSTs to worry about capacity,
+            // but `VecDeque` can't handle as much length as `Vec`.
+            assert!(len < MAXIMUM_ZST_CAPACITY, "capacity overflow");
+        } else {
+            // We need to resize if the capacity is not a power of two, too small or
+            // doesn't have at least one free space. We do this while it's still in
+            // the `Vec` so the items will drop on panic.
+            let min_cap = cmp::max(MINIMUM_CAPACITY, len) + 1;
+            let cap = cmp::max(min_cap, other.capacity()).next_power_of_two();
+            if other.capacity() != cap {
+                other.reserve_exact(cap - len);
             }
+        }
 
+        unsafe {
+            let (other_buf, len, capacity) = other.into_raw_parts();
+            let buf = RawVec::from_raw_parts(other_buf, capacity);
             VecDeque { tail: 0, head: len, buf }
         }
     }

library/alloc/src/collections/vec_deque/tests.rs

@@ -457,6 +457,21 @@ fn test_from_vec() {
             assert!(vd.into_iter().eq(vec));
         }
     }
+
+    let vec = Vec::from([(); MAXIMUM_ZST_CAPACITY - 1]);
+    let vd = VecDeque::from(vec.clone());
+    assert!(vd.cap().is_power_of_two());
+    assert_eq!(vd.len(), vec.len());
+}
+
+#[test]
+#[should_panic = "capacity overflow"]
+fn test_from_vec_zst_overflow() {
+    use crate::vec::Vec;
+    let vec = Vec::from([(); MAXIMUM_ZST_CAPACITY]);
+    let vd = VecDeque::from(vec.clone()); // no room for +1
+    assert!(vd.cap().is_power_of_two());
+    assert_eq!(vd.len(), vec.len());
 }
 
 #[test]

library/core/src/iter/adapters/filter.rs

@@ -13,7 +13,8 @@ use crate::ops::Try;
 #[stable(feature = "rust1", since = "1.0.0")]
 #[derive(Clone)]
 pub struct Filter<I, P> {
-    iter: I,
+    // Used for `SplitWhitespace` and `SplitAsciiWhitespace` `as_str` methods
+    pub(crate) iter: I,
     predicate: P,
 }
 impl<I, P> Filter<I, P> {

library/core/src/iter/adapters/map.rs

@@ -57,7 +57,8 @@ use crate::ops::Try;
 #[stable(feature = "rust1", since = "1.0.0")]
 #[derive(Clone)]
 pub struct Map<I, F> {
-    iter: I,
+    // Used for `SplitWhitespace` and `SplitAsciiWhitespace` `as_str` methods
+    pub(crate) iter: I,
     f: F,
 }
 

library/core/src/macros/panic.md

@@ -9,11 +9,15 @@ tests. `panic!` is closely tied with the `unwrap` method of both
 [`Option`][ounwrap] and [`Result`][runwrap] enums. Both implementations call
 `panic!` when they are set to [`None`] or [`Err`] variants.
 
-This macro is used to inject panic into a Rust thread, causing the thread to
-panic entirely. This macro panics with a string and uses the [`format!`] syntax
-for building the message.
-
-Each thread's panic can be reaped as the [`Box`]`<`[`Any`]`>` type,
+When using `panic!()` you can specify a string payload, that is built using
+the [`format!`] syntax. That payload is used when injecting the panic into
+the calling Rust thread, causing the thread to panic entirely.
+
+The behavior of the default `std` hook, i.e. the code that runs directly
+after the panic is invoked, is to print the message payload to
+`stderr` along with the file/line/column information of the `panic!()`
+call. You can override the panic hook using [`std::panic::set_hook()`].
+Inside the hook a panic can be accessed as a `&dyn Any + Send`,
 which contains either a `&str` or `String` for regular `panic!()` invocations.
 To panic with a value of another other type, [`panic_any`] can be used.
 
@@ -26,6 +30,7 @@ See also the macro [`compile_error!`], for raising errors during compilation.
 
 [ounwrap]: Option::unwrap
 [runwrap]: Result::unwrap
+[`std::panic::set_hook()`]: ../std/panic/fn.set_hook.html
 [`panic_any`]: ../std/panic/fn.panic_any.html
 [`Box`]: ../std/boxed/struct.Box.html
 [`Any`]: crate::any::Any

library/core/src/slice/iter.rs

@@ -335,9 +335,11 @@ pub struct Split<'a, T: 'a, P>
 where
     P: FnMut(&T) -> bool,
 {
-    v: &'a [T],
+    // Used for `SplitWhitespace` and `SplitAsciiWhitespace` `as_str` methods
+    pub(crate) v: &'a [T],
     pred: P,
-    finished: bool,
+    // Used for `SplitAsciiWhitespace` `as_str` method
+    pub(crate) finished: bool,
 }
 
 impl<'a, T: 'a, P: FnMut(&T) -> bool> Split<'a, T, P> {

library/core/src/str/iter.rs

@@ -1200,6 +1200,30 @@ impl<'a> DoubleEndedIterator for SplitWhitespace<'a> {
 #[stable(feature = "fused", since = "1.26.0")]
 impl FusedIterator for SplitWhitespace<'_> {}
 
+impl<'a> SplitWhitespace<'a> {
+    /// Returns remainder of the splitted string
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(str_split_whitespace_as_str)]
+    ///
+    /// let mut split = "Mary had a little lamb".split_whitespace();
+    /// assert_eq!(split.as_str(), "Mary had a little lamb");
+    ///
+    /// split.next();
+    /// assert_eq!(split.as_str(), "had a little lamb");
+    ///
+    /// split.by_ref().for_each(drop);
+    /// assert_eq!(split.as_str(), "");
+    /// ```
+    #[inline]
+    #[unstable(feature = "str_split_whitespace_as_str", issue = "77998")]
+    pub fn as_str(&self) -> &'a str {
+        self.inner.iter.as_str()
+    }
+}
+
 #[stable(feature = "split_ascii_whitespace", since = "1.34.0")]
 impl<'a> Iterator for SplitAsciiWhitespace<'a> {
     type Item = &'a str;
@@ -1231,6 +1255,35 @@ impl<'a> DoubleEndedIterator for SplitAsciiWhitespace<'a> {
 #[stable(feature = "split_ascii_whitespace", since = "1.34.0")]
 impl FusedIterator for SplitAsciiWhitespace<'_> {}
 
+impl<'a> SplitAsciiWhitespace<'a> {
+    /// Returns remainder of the splitted string
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(str_split_whitespace_as_str)]
+    ///
+    /// let mut split = "Mary had a little lamb".split_ascii_whitespace();
+    /// assert_eq!(split.as_str(), "Mary had a little lamb");
+    ///
+    /// split.next();
+    /// assert_eq!(split.as_str(), "had a little lamb");
+    ///
+    /// split.by_ref().for_each(drop);
+    /// assert_eq!(split.as_str(), "");
+    /// ```
+    #[inline]
+    #[unstable(feature = "str_split_whitespace_as_str", issue = "77998")]
+    pub fn as_str(&self) -> &'a str {
+        if self.inner.iter.iter.finished {
+            return "";
+        }
+
+        // SAFETY: Slice is created from str.
+        unsafe { crate::str::from_utf8_unchecked(&self.inner.iter.iter.v) }
+    }
+}
+
 #[stable(feature = "split_inclusive", since = "1.51.0")]
 impl<'a, P: Pattern<'a>> Iterator for SplitInclusive<'a, P> {
     type Item = &'a str;

library/std/src/collections/mod.rs

@@ -401,9 +401,10 @@
 #![stable(feature = "rust1", since = "1.0.0")]
 
 #[stable(feature = "rust1", since = "1.0.0")]
-#[rustc_deprecated(reason = "moved to `std::ops::Bound`", since = "1.52.0")]
+// FIXME(#82080) The deprecation here is only theoretical, and does not actually produce a warning.
+#[rustc_deprecated(reason = "moved to `std::ops::Bound`", since = "1.26.0")]
 #[doc(hidden)]
-pub type Bound<T> = crate::ops::Bound<T>;
+pub use crate::ops::Bound;
 
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use alloc_crate::collections::{binary_heap, btree_map, btree_set};