Auto merge of rust-lang#83105 - JohnTitor:rollup-tqpm8pb, r=JohnTitor

Rollup of 10 pull requests

Successful merges:

 - rust-lang#81465 (Add documentation about formatting `Duration` values)
 - rust-lang#82121 (Implement Extend and FromIterator for OsString)
 - rust-lang#82617 (Document `everybody_loops`)
 - rust-lang#82789 (Get with field index from pattern slice instead of directly indexing)
 - rust-lang#82798 (Rename `rustdoc` to `rustdoc::all`)
 - rust-lang#82804 (std: Fix a bug on the wasm32-wasi target opening files)
 - rust-lang#82943 (Demonstrate best practice for feeding stdin of a child processes)
 - rust-lang#83066 (Add `reverse` search alias for Iterator::rev())
 - rust-lang#83070 (Update cargo)
 - rust-lang#83081 (Fix panic message of `assert_failed_inner`)

Failed merges:

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

Author: bors

compiler/rustc_interface/src/util.rs

@@ -712,16 +712,24 @@ pub fn non_durable_rename(src: &Path, dst: &Path) -> std::io::Result<()> {
     std::fs::rename(src, dst)
 }
 
-// Note: Also used by librustdoc, see PR #43348. Consider moving this struct elsewhere.
-//
-// FIXME: Currently the `everybody_loops` transformation is not applied to:
-//  * `const fn`, due to issue #43636 that `loop` is not supported for const evaluation. We are
-//    waiting for miri to fix that.
-//  * `impl Trait`, due to issue #43869 that functions returning impl Trait cannot be diverging.
-//    Solving this may require `!` to implement every trait, which relies on the an even more
-//    ambitious form of the closed RFC #1637. See also [#34511].
-//
-// [#34511]: https://github.com/rust-lang/rust/issues/34511#issuecomment-322340401
+/// Replaces function bodies with `loop {}` (an infinite loop). This gets rid of
+/// all semantic errors in the body while still satisfying the return type,
+/// except in certain cases, see below for more.
+///
+/// This pass is known as `everybody_loops`. Very punny.
+///
+/// As of March 2021, `everybody_loops` is only used for the
+/// `-Z unpretty=everybody_loops` debugging option.
+///
+/// FIXME: Currently the `everybody_loops` transformation is not applied to:
+///  * `const fn`; support could be added, but hasn't. Originally `const fn`
+///    was skipped due to issue #43636 that `loop` was not supported for
+///    const evaluation.
+///  * `impl Trait`, due to issue #43869 that functions returning impl Trait cannot be diverging.
+///    Solving this may require `!` to implement every trait, which relies on the an even more
+///    ambitious form of the closed RFC #1637. See also [#34511].
+///
+/// [#34511]: https://github.com/rust-lang/rust/issues/34511#issuecomment-322340401
 pub struct ReplaceBodyWithLoop<'a, 'b> {
     within_static_or_const: bool,
     nested_blocks: Option<Vec<ast::Block>>,

compiler/rustc_lint/src/lib.rs

@@ -346,6 +346,7 @@ fn register_builtins(store: &mut LintStore, no_interleave_lints: bool) {
         "intra_doc_link_resolution_failure",
         "use `rustdoc::broken_intra_doc_links` instead",
     );
+    store.register_removed("rustdoc", "use `rustdoc::all` instead");
 
     store.register_removed("unknown_features", "replaced by an error");
     store.register_removed("unsigned_negation", "replaced by negate_unsigned feature gate");

compiler/rustc_mir_build/src/thir/pattern/deconstruct_pat.rs

@@ -1343,7 +1343,9 @@ impl<'p, 'tcx> Fields<'p, 'tcx> {
         match &mut fields {
             Fields::Vec(pats) => {
                 for (i, pat) in new_pats {
-                    pats[i] = pat
+                    if let Some(p) = pats.get_mut(i) {
+                        *p = pat;
+                    }
                 }
             }
             Fields::Filtered { fields, .. } => {

library/core/src/iter/traits/iterator.rs

@@ -2737,6 +2737,7 @@ pub trait Iterator {
     /// assert_eq!(iter.next(), None);
     /// ```
     #[inline]
+    #[doc(alias = "reverse")]
     #[stable(feature = "rust1", since = "1.0.0")]
     fn rev(self) -> Rev<Self>
     where

library/core/src/panicking.rs

@@ -154,7 +154,7 @@ fn assert_failed_inner(
         Some(args) => panic!(
             r#"assertion failed: `(left {} right)`
   left: `{:?}`,
- right: `{:?}: {}`"#,
+ right: `{:?}`: {}"#,
             op, left, right, args
         ),
         None => panic!(

library/core/src/time.rs

@@ -48,6 +48,17 @@ const MICROS_PER_SEC: u64 = 1_000_000;
 ///
 /// let ten_millis = Duration::from_millis(10);
 /// ```
+///
+/// # Formatting `Duration` values
+///
+/// `Duration` intentionally does not have a `Display` impl, as there are a
+/// variety of ways to format spans of time for human readability. `Duration`
+/// provides a `Debug` impl that shows the full precision of the value.
+///
+/// The `Debug` output uses the non-ASCII "µs" suffix for microseconds. If your
+/// program output may appear in contexts that cannot rely on full Unicode
+/// compatibility, you may wish to format `Duration` objects yourself or use a
+/// crate to do so.
 #[stable(feature = "duration", since = "1.3.0")]
 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Default)]
 pub struct Duration {

library/std/src/ffi/os_str.rs

@@ -5,6 +5,7 @@ use crate::borrow::{Borrow, Cow};
 use crate::cmp;
 use crate::fmt;
 use crate::hash::{Hash, Hasher};
+use crate::iter::{Extend, FromIterator};
 use crate::ops;
 use crate::rc::Rc;
 use crate::str::FromStr;
@@ -1192,3 +1193,88 @@ impl FromStr for OsString {
         Ok(OsString::from(s))
     }
 }
+
+#[stable(feature = "osstring_extend", since = "1.52.0")]
+impl Extend<OsString> for OsString {
+    #[inline]
+    fn extend<T: IntoIterator<Item = OsString>>(&mut self, iter: T) {
+        for s in iter {
+            self.push(&s);
+        }
+    }
+}
+
+#[stable(feature = "osstring_extend", since = "1.52.0")]
+impl<'a> Extend<&'a OsStr> for OsString {
+    #[inline]
+    fn extend<T: IntoIterator<Item = &'a OsStr>>(&mut self, iter: T) {
+        for s in iter {
+            self.push(s);
+        }
+    }
+}
+
+#[stable(feature = "osstring_extend", since = "1.52.0")]
+impl<'a> Extend<Cow<'a, OsStr>> for OsString {
+    #[inline]
+    fn extend<T: IntoIterator<Item = Cow<'a, OsStr>>>(&mut self, iter: T) {
+        for s in iter {
+            self.push(&s);
+        }
+    }
+}
+
+#[stable(feature = "osstring_extend", since = "1.52.0")]
+impl FromIterator<OsString> for OsString {
+    #[inline]
+    fn from_iter<I: IntoIterator<Item = OsString>>(iter: I) -> Self {
+        let mut iterator = iter.into_iter();
+
+        // Because we're iterating over `OsString`s, we can avoid at least
+        // one allocation by getting the first string from the iterator
+        // and appending to it all the subsequent strings.
+        match iterator.next() {
+            None => OsString::new(),
+            Some(mut buf) => {
+                buf.extend(iterator);
+                buf
+            }
+        }
+    }
+}
+
+#[stable(feature = "osstring_extend", since = "1.52.0")]
+impl<'a> FromIterator<&'a OsStr> for OsString {
+    #[inline]
+    fn from_iter<I: IntoIterator<Item = &'a OsStr>>(iter: I) -> Self {
+        let mut buf = Self::new();
+        for s in iter {
+            buf.push(s);
+        }
+        buf
+    }
+}
+
+#[stable(feature = "osstring_extend", since = "1.52.0")]
+impl<'a> FromIterator<Cow<'a, OsStr>> for OsString {
+    #[inline]
+    fn from_iter<I: IntoIterator<Item = Cow<'a, OsStr>>>(iter: I) -> Self {
+        let mut iterator = iter.into_iter();
+
+        // Because we're iterating over `OsString`s, we can avoid at least
+        // one allocation by getting the first owned string from the iterator
+        // and appending to it all the subsequent strings.
+        match iterator.next() {
+            None => OsString::new(),
+            Some(Cow::Owned(mut buf)) => {
+                buf.extend(iterator);
+                buf
+            }
+            Some(Cow::Borrowed(buf)) => {
+                let mut buf = OsString::from(buf);
+                buf.extend(iterator);
+                buf
+            }
+        }
+    }
+}

library/std/src/process.rs

@@ -71,11 +71,15 @@
 //!     .spawn()
 //!     .expect("failed to execute child");
 //!
-//! {
-//!     // limited borrow of stdin
-//!     let stdin = child.stdin.as_mut().expect("failed to get stdin");
+//! // If the child process fills its stdout buffer, it may end up
+//! // waiting until the parent reads the stdout, and not be able to
+//! // read stdin in the meantime, causing a deadlock.
+//! // Writing from another thread ensures that stdout is being read
+//! // at the same time, avoiding the problem.
+//! let mut stdin = child.stdin.take().expect("failed to get stdin");
+//! std::thread::spawn(move || {
 //!     stdin.write_all(b"test").expect("failed to write to stdin");
-//! }
+//! });
 //!
 //! let output = child
 //!     .wait_with_output()
@@ -1145,14 +1149,21 @@ impl Stdio {
     ///     .spawn()
     ///     .expect("Failed to spawn child process");
     ///
-    /// {
-    ///     let stdin = child.stdin.as_mut().expect("Failed to open stdin");
+    /// let mut stdin = child.stdin.take().expect("Failed to open stdin");
+    /// std::thread::spawn(move || {
     ///     stdin.write_all("Hello, world!".as_bytes()).expect("Failed to write to stdin");
-    /// }
+    /// });
     ///
     /// let output = child.wait_with_output().expect("Failed to read stdout");
     /// assert_eq!(String::from_utf8_lossy(&output.stdout), "!dlrow ,olleH");
     /// ```
+    ///
+    /// Writing more than a pipe buffer's worth of input to stdin without also reading
+    /// stdout and stderr at the same time may cause a deadlock.
+    /// This is an issue when running any program that doesn't guarantee that it reads
+    /// its entire stdin before writing more than a pipe buffer's worth of output.
+    /// The size of a pipe buffer varies on different targets.
+    ///
     #[stable(feature = "process", since = "1.0.0")]
     pub fn piped() -> Stdio {
         Stdio(imp::Stdio::MakePipe)

library/std/src/sys/wasi/fs.rs

@@ -650,13 +650,11 @@ fn open_parent(p: &Path) -> io::Result<(ManuallyDrop<WasiFd>, PathBuf)> {
                 );
                 return Err(io::Error::new(io::ErrorKind::Other, msg));
             }
-            let len = CStr::from_ptr(buf.as_ptr().cast()).to_bytes().len();
-            buf.set_len(len);
-            buf.shrink_to_fit();
+            let relative = CStr::from_ptr(relative_path).to_bytes().to_vec();
 
             return Ok((
                 ManuallyDrop::new(WasiFd::from_raw(fd as u32)),
-                PathBuf::from(OsString::from_vec(buf)),
+                PathBuf::from(OsString::from_vec(relative)),
             ));
         }
     }

src/librustdoc/lint.rs

@@ -175,8 +175,8 @@ crate fn register_lints(_sess: &Session, lint_store: &mut LintStore) {
     lint_store.register_lints(&**RUSTDOC_LINTS);
     lint_store.register_group(
         true,
-        "rustdoc",
-        None,
+        "rustdoc::all",
+        Some("rustdoc"),
         RUSTDOC_LINTS.iter().map(|&lint| LintId::of(lint)).collect(),
     );
     for lint in &*RUSTDOC_LINTS {