Auto merge of #66366 - JohnTitor:rollup-xlc1bj2, r=JohnTitor

Rollup of 14 pull requests

Successful merges:

 - #65932 (download .tar.xz if python3 is used)
 - #66094 (Fix documentation for `Iterator::count()`.)
 - #66166 (rename cfg(rustdoc) into cfg(doc))
 - #66186 (Add long error explanation for E0623)
 - #66227 (docs: Fix link to BufWriter::flush)
 - #66248 (add raw ptr variant of UnsafeCell::get)
 - #66292 (add Result::map_or)
 - #66297 (Add a callback that allows compiler consumers to override queries.)
 - #66317 (Use a relative bindir for rustdoc to find rustc)
 - #66330 (Improve non-exhaustiveness handling in usefulness checking)
 - #66331 (Add some tests for fixed ICEs)
 - #66334 (Move Session fields to CrateStore)
 - #66335 (Move self-profile infrastructure to data structures)
 - #66337 (Remove dead code for encoding/decoding lint IDs)

Failed merges:

r? @ghost

Cargo.lock

@@ -3120,7 +3120,6 @@ dependencies = [
  "graphviz",
  "jobserver",
  "log",
- "measureme",
  "num_cpus",
  "parking_lot 0.9.0",
  "polonius-engine",
@@ -3470,6 +3469,7 @@ dependencies = [
 name = "rustc_data_structures"
 version = "0.0.0"
 dependencies = [
+ "bitflags",
  "cfg-if",
  "crossbeam-utils 0.6.5",
  "ena",
@@ -3478,6 +3478,7 @@ dependencies = [
  "jobserver",
  "lazy_static 1.3.0",
  "log",
+ "measureme",
  "parking_lot 0.9.0",
  "rustc-hash",
  "rustc-rayon 0.3.0",

src/bootstrap/bin/rustdoc.rs

@@ -25,7 +25,7 @@ fn main() {
     let mut dylib_path = bootstrap::util::dylib_path();
     dylib_path.insert(0, PathBuf::from(libdir.clone()));
 
-    //FIXME(misdreavus): once stdsimd uses cfg(rustdoc) instead of cfg(dox), remove the `--cfg dox`
+    //FIXME(misdreavus): once stdsimd uses cfg(doc) instead of cfg(dox), remove the `--cfg dox`
     //arguments here
     let mut cmd = Command::new(rustdoc);
     cmd.args(&args)

src/bootstrap/bootstrap.py

@@ -102,10 +102,10 @@ def verify(path, sha_path, verbose):
     return verified
 
 
-def unpack(tarball, dst, verbose=False, match=None):
+def unpack(tarball, tarball_suffix, dst, verbose=False, match=None):
     """Unpack the given tarball file"""
     print("extracting", tarball)
-    fname = os.path.basename(tarball).replace(".tar.gz", "")
+    fname = os.path.basename(tarball).replace(tarball_suffix, "")
     with contextlib.closing(tarfile.open(tarball)) as tar:
         for member in tar.getnames():
             if "/" not in member:
@@ -331,6 +331,7 @@ def __init__(self):
         self.use_vendored_sources = ''
         self.verbose = False
 
+
     def download_stage0(self):
         """Fetch the build system for Rust, written in Rust
 
@@ -344,18 +345,30 @@ def download_stage0(self):
         rustc_channel = self.rustc_channel
         cargo_channel = self.cargo_channel
 
+        def support_xz():
+            try:
+                with tempfile.NamedTemporaryFile(delete=False) as temp_file:
+                    temp_path = temp_file.name
+                with tarfile.open(temp_path, "w:xz") as tar:
+                    pass
+                return True
+            except tarfile.CompressionError:
+                return False
+
         if self.rustc().startswith(self.bin_root()) and \
                 (not os.path.exists(self.rustc()) or
                  self.program_out_of_date(self.rustc_stamp())):
             if os.path.exists(self.bin_root()):
                 shutil.rmtree(self.bin_root())
-            filename = "rust-std-{}-{}.tar.gz".format(
-                rustc_channel, self.build)
+            tarball_suffix = '.tar.xz' if support_xz() else '.tar.gz'
+            filename = "rust-std-{}-{}{}".format(
+                rustc_channel, self.build, tarball_suffix)
             pattern = "rust-std-{}".format(self.build)
-            self._download_stage0_helper(filename, pattern)
+            self._download_stage0_helper(filename, pattern, tarball_suffix)
 
-            filename = "rustc-{}-{}.tar.gz".format(rustc_channel, self.build)
-            self._download_stage0_helper(filename, "rustc")
+            filename = "rustc-{}-{}{}".format(rustc_channel, self.build,
+                                              tarball_suffix)
+            self._download_stage0_helper(filename, "rustc", tarball_suffix)
             self.fix_executable("{}/bin/rustc".format(self.bin_root()))
             self.fix_executable("{}/bin/rustdoc".format(self.bin_root()))
             with output(self.rustc_stamp()) as rust_stamp:
@@ -365,20 +378,22 @@ def download_stage0(self):
             # libraries/binaries that are included in rust-std with
             # the system MinGW ones.
             if "pc-windows-gnu" in self.build:
-                filename = "rust-mingw-{}-{}.tar.gz".format(
-                    rustc_channel, self.build)
-                self._download_stage0_helper(filename, "rust-mingw")
+                filename = "rust-mingw-{}-{}{}".format(
+                    rustc_channel, self.build, tarball_suffix)
+                self._download_stage0_helper(filename, "rust-mingw", tarball_suffix)
 
         if self.cargo().startswith(self.bin_root()) and \
                 (not os.path.exists(self.cargo()) or
                  self.program_out_of_date(self.cargo_stamp())):
-            filename = "cargo-{}-{}.tar.gz".format(cargo_channel, self.build)
-            self._download_stage0_helper(filename, "cargo")
+            tarball_suffix = '.tar.xz' if support_xz() else '.tar.gz'
+            filename = "cargo-{}-{}{}".format(cargo_channel, self.build,
+                                              tarball_suffix)
+            self._download_stage0_helper(filename, "cargo", tarball_suffix)
             self.fix_executable("{}/bin/cargo".format(self.bin_root()))
             with output(self.cargo_stamp()) as cargo_stamp:
                 cargo_stamp.write(self.date)
 
-    def _download_stage0_helper(self, filename, pattern):
+    def _download_stage0_helper(self, filename, pattern, tarball_suffix):
         cache_dst = os.path.join(self.build_dir, "cache")
         rustc_cache = os.path.join(cache_dst, self.date)
         if not os.path.exists(rustc_cache):
@@ -388,7 +403,7 @@ def _download_stage0_helper(self, filename, pattern):
         tarball = os.path.join(rustc_cache, filename)
         if not os.path.exists(tarball):
             get("{}/{}".format(url, filename), tarball, verbose=self.verbose)
-        unpack(tarball, self.bin_root(), match=pattern, verbose=self.verbose)
+        unpack(tarball, tarball_suffix, self.bin_root(), match=pattern, verbose=self.verbose)
 
     @staticmethod
     def fix_executable(fname):

src/bootstrap/builder.rs

@@ -1242,7 +1242,8 @@ impl<'a> Builder<'a> {
             cargo.arg("--frozen");
         }
 
-        cargo.env("RUSTC_INSTALL_BINDIR", &self.config.bindir);
+        // Try to use a sysroot-relative bindir, in case it was configured absolutely.
+        cargo.env("RUSTC_INSTALL_BINDIR", self.config.bindir_relative());
 
         self.ci_env.force_coloring_in_ci(&mut cargo);
 

src/bootstrap/config.rs

@@ -647,6 +647,20 @@ impl Config {
         config
     }
 
+    /// Try to find the relative path of `bindir`, otherwise return it in full.
+    pub fn bindir_relative(&self) -> &Path {
+        let bindir = &self.bindir;
+        if bindir.is_absolute() {
+            // Try to make it relative to the prefix.
+            if let Some(prefix) = &self.prefix {
+                if let Ok(stripped) = bindir.strip_prefix(prefix) {
+                    return stripped;
+                }
+            }
+        }
+        bindir
+    }
+
     /// Try to find the relative path of `libdir`.
     pub fn libdir_relative(&self) -> Option<&Path> {
         let libdir = self.libdir.as_ref()?;

src/doc/rustdoc/src/unstable-features.md

@@ -106,24 +106,24 @@ item, it will be accompanied by a banner explaining that the item is only availa
 platforms.
 
 For Rustdoc to document an item, it needs to see it, regardless of what platform it's currently
-running on. To aid this, Rustdoc sets the flag `#[cfg(rustdoc)]` when running on your crate.
+running on. To aid this, Rustdoc sets the flag `#[cfg(doc)]` when running on your crate.
 Combining this with the target platform of a given item allows it to appear when building your crate
 normally on that platform, as well as when building documentation anywhere.
 
-For example, `#[cfg(any(windows, rustdoc))]` will preserve the item either on Windows or during the
+For example, `#[cfg(any(windows, doc))]` will preserve the item either on Windows or during the
 documentation process. Then, adding a new attribute `#[doc(cfg(windows))]` will tell Rustdoc that
 the item is supposed to be used on Windows. For example:
 
 ```rust
 #![feature(doc_cfg)]
 
 /// Token struct that can only be used on Windows.
-#[cfg(any(windows, rustdoc))]
+#[cfg(any(windows, doc))]
 #[doc(cfg(windows))]
 pub struct WindowsToken;
 
 /// Token struct that can only be used on Unix.
-#[cfg(any(unix, rustdoc))]
+#[cfg(any(unix, doc))]
 #[doc(cfg(unix))]
 pub struct UnixToken;
 ```

src/doc/unstable-book/src/language-features/doc-cfg.md

@@ -13,7 +13,7 @@ This attribute has two effects:
 2. The item's doc-tests will only run on the specific platform.
 
 In addition to allowing the use of the `#[doc(cfg)]` attribute, this feature enables the use of a
-special conditional compilation flag, `#[cfg(rustdoc)]`, set whenever building documentation on your
+special conditional compilation flag, `#[cfg(doc)]`, set whenever building documentation on your
 crate.
 
 This feature was introduced as part of PR [#43348] to allow the platform-specific parts of the
@@ -22,7 +22,7 @@ standard library be documented.
 ```rust
 #![feature(doc_cfg)]
 
-#[cfg(any(windows, rustdoc))]
+#[cfg(any(windows, doc))]
 #[doc(cfg(windows))]
 /// The application's icon in the notification area (a.k.a. system tray).
 ///

src/libcore/cell.rs

@@ -1545,9 +1545,46 @@ impl<T: ?Sized> UnsafeCell<T> {
     #[stable(feature = "rust1", since = "1.0.0")]
     pub const fn get(&self) -> *mut T {
         // We can just cast the pointer from `UnsafeCell<T>` to `T` because of
-        // #[repr(transparent)]
+        // #[repr(transparent)]. This exploits libstd's special status, there is
+        // no guarantee for user code that this will work in future versions of the compiler!
         self as *const UnsafeCell<T> as *const T as *mut T
     }
+
+    /// Gets a mutable pointer to the wrapped value.
+    /// The difference to [`get`] is that this function accepts a raw pointer,
+    /// which is useful to avoid the creation of temporary references.
+    ///
+    /// The result can be cast to a pointer of any kind.
+    /// Ensure that the access is unique (no active references, mutable or not)
+    /// when casting to `&mut T`, and ensure that there are no mutations
+    /// or mutable aliases going on when casting to `&T`.
+    ///
+    /// [`get`]: #method.get
+    ///
+    /// # Examples
+    ///
+    /// Gradual initialization of an `UnsafeCell` requires `raw_get`, as
+    /// calling `get` would require creating a reference to uninitialized data:
+    ///
+    /// ```
+    /// #![feature(unsafe_cell_raw_get)]
+    /// use std::cell::UnsafeCell;
+    /// use std::mem::MaybeUninit;
+    ///
+    /// let m = MaybeUninit::<UnsafeCell<i32>>::uninit();
+    /// unsafe { UnsafeCell::raw_get(m.as_ptr()).write(5); }
+    /// let uc = unsafe { m.assume_init() };
+    ///
+    /// assert_eq!(uc.into_inner(), 5);
+    /// ```
+    #[inline]
+    #[unstable(feature = "unsafe_cell_raw_get", issue = "66358")]
+    pub const fn raw_get(this: *const Self) -> *mut T {
+        // We can just cast the pointer from `UnsafeCell<T>` to `T` because of
+        // #[repr(transparent)]. This exploits libstd's special status, there is
+        // no guarantee for user code that this will work in future versions of the compiler!
+        this as *const T as *mut T
+    }
 }
 
 #[stable(feature = "unsafe_cell_default", since = "1.10.0")]

src/libcore/iter/traits/iterator.rs

@@ -201,12 +201,13 @@ pub trait Iterator {
 
     /// Consumes the iterator, counting the number of iterations and returning it.
     ///
-    /// This method will evaluate the iterator until its [`next`] returns
-    /// [`None`]. Once [`None`] is encountered, `count()` returns the number of
-    /// times it called [`next`].
+    /// This method will call [`next`] repeatedly until [`None`] is encountered,
+    /// returning the number of times it saw [`Some`]. Note that [`next`] has to be
+    /// called at least once even if the iterator does not have any elements.
     ///
     /// [`next`]: #tymethod.next
     /// [`None`]: ../../std/option/enum.Option.html#variant.None
+    /// [`Some`]: ../../std/option/enum.Option.html#variant.Some
     ///
     /// # Overflow Behavior
     ///

src/libcore/result.rs

@@ -514,6 +514,28 @@ impl<T, E> Result<T, E> {
         }
     }
 
+    /// Applies a function to the contained value (if any),
+    /// or returns the provided default (if not).
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(result_map_or)]
+    /// let x: Result<_, &str> = Ok("foo");
+    /// assert_eq!(x.map_or(42, |v| v.len()), 3);
+    ///
+    /// let x: Result<&str, _> = Err("bar");
+    /// assert_eq!(x.map_or(42, |v| v.len()), 42);
+    /// ```
+    #[inline]
+    #[unstable(feature = "result_map_or", issue = "66293")]
+    pub fn map_or<U, F: FnOnce(T) -> U>(self, default: U, f: F) -> U {
+        match self {
+            Ok(t) => f(t),
+            Err(_) => default,
+        }
+    }
+
     /// Maps a `Result<T, E>` to `U` by applying a function to a
     /// contained [`Ok`] value, or a fallback function to a
     /// contained [`Err`] value.

src/librustc/Cargo.toml

@@ -40,4 +40,3 @@ byteorder = { version = "1.3" }
 chalk-engine = { version = "0.9.0", default-features=false }
 rustc_fs_util = { path = "../librustc_fs_util" }
 smallvec = { version = "1.0", features = ["union", "may_dangle"] }
-measureme = "0.4"

src/librustc/error_codes.rs

@@ -1896,6 +1896,51 @@ fn foo<'a>(x: &'a i32, y: &i32) -> &'a i32 {
 ```
 "##,
 
+E0623: r##"
+A lifetime didn't match what was expected.
+
+Erroneous code example:
+
+```compile_fail,E0623
+struct Foo<'a> {
+    x: &'a isize,
+}
+
+fn bar<'short, 'long>(c: Foo<'short>, l: &'long isize) {
+    let _: Foo<'long> = c; // error!
+}
+```
+
+In this example, we tried to set a value with an incompatible lifetime to
+another one (`'long` is unrelated to `'short`). We can solve this issue in
+two different ways:
+
+Either we make `'short` live at least as long as `'long`:
+
+```
+struct Foo<'a> {
+    x: &'a isize,
+}
+
+// we set 'short to live at least as long as 'long
+fn bar<'short: 'long, 'long>(c: Foo<'short>, l: &'long isize) {
+    let _: Foo<'long> = c; // ok!
+}
+```
+
+Or we use only one lifetime:
+
+```
+struct Foo<'a> {
+    x: &'a isize,
+}
+
+fn bar<'short>(c: Foo<'short>, l: &'short isize) {
+    let _: Foo<'short> = c; // ok!
+}
+```
+"##,
+
 E0635: r##"
 The `#![feature]` attribute specified an unknown feature.
 
@@ -2329,7 +2374,6 @@ the future, [RFC 2091] prohibits their implementation without a follow-up RFC.
     E0488, // lifetime of variable does not enclose its declaration
     E0489, // type/lifetime parameter not in scope here
     E0490, // a value of type `..` is borrowed for too long
-    E0623, // lifetime mismatch where both parameters are anonymous regions
     E0628, // generators cannot have explicit parameters
     E0631, // type mismatch in closure arguments
     E0637, // "'_" is not a valid lifetime bound

src/librustc/lib.rs

@@ -124,7 +124,6 @@ pub mod util {
     pub mod captures;
     pub mod common;
     pub mod nodemap;
-    pub mod profiling;
     pub mod bug;
 }