Auto merge of #74313 - Manishearth:rollup-b55rn6t, r=Manishearth

Rollup of 8 pull requests

Successful merges:

 - #73354 (Update RELEASES.md for 1.45.0)
 - #73852 (rustdoc: insert newlines between attributes)
 - #73867 (Document the union keyword)
 - #74046 (Fix caching issue when building tools.)
 - #74123 (clean up E0718 explanation)
 - #74147 (rustdoc: Allow linking from private items to private types)
 - #74285 (#71669: add ui, codegen tests for volatile + nearby int intrinsics)
 - #74286 (Added detailed error code explanation for issue E0688 in Rust compiler.)

Failed merges:

r? @ghost

RELEASES.md

@@ -1,3 +1,166 @@
+Version 1.45.0 (2020-07-16)
+==========================
+
+Language
+--------
+- [Out of range float to int conversions using `as` has been defined as a saturating
+  conversion.][71269] This was previously undefined behaviour, but you can use the
+   `{f64, f32}::to_int_unchecked` methods to continue using the current behaviour, which
+   may be desirable in rare performance sensitive situations.
+- [`mem::Discriminant<T>` now uses `T`'s discriminant type instead of always
+  using `u64`.][70705]
+- [Function like procedural macros can now be used in expression, pattern, and  statement
+  positions.][68717] This means you can now use a function-like procedural macro
+  anywhere you can use a declarative (`macro_rules!`) macro.
+
+Compiler
+--------
+- [You can now override individual target features through the `target-feature`
+  flag.][72094] E.g. `-C target-feature=+avx2 -C target-feature=+fma` is now
+  equivalent to `-C target-feature=+avx2,+fma`.
+- [Added the `force-unwind-tables` flag.][69984] This option allows
+  rustc to always generate unwind tables regardless of panic strategy.
+- [Added the `embed-bitcode` flag.][71716] This codegen flag allows rustc
+  to include LLVM bitcode into generated `rlib`s (this is on by default).
+- [Added the `tiny` value to the `code-model` codegen flag.][72397]
+- [Added tier 3 support\* for the `mipsel-sony-psp` target.][72062]
+- [Added tier 3 support for the `thumbv7a-uwp-windows-msvc` target.][72133]
+
+\* Refer to Rust's [platform support page][forge-platform-support] for more
+information on Rust's tiered platform support.
+
+
+Libraries
+---------
+- [`net::{SocketAddr, SocketAddrV4, SocketAddrV6}` now implements `PartialOrd`
+  and `Ord`.][72239]
+- [`proc_macro::TokenStream` now implements `Default`.][72234]
+- [You can now use `char` with
+  `ops::{Range, RangeFrom, RangeFull, RangeInclusive, RangeTo}` to iterate over
+  a range of codepoints.][72413] E.g.
+  you can now write the following;
+  ```rust
+  for ch in 'a'..='z' {
+      print!("{}", ch);
+  }
+  println!();
+  // Prints "abcdefghijklmnopqrstuvwxyz"
+  ```
+- [`OsString` now implements `FromStr`.][71662]
+- [The `saturating_neg` method as been added to all signed integer primitive
+  types, and the `saturating_abs` method has been added for all integer
+  primitive types.][71886]
+- [`Arc<T>`, `Rc<T>` now implement  `From<Cow<'_, T>>`, and `Box` now
+  implements `From<Cow>` when `T` is `[T: Copy]`, `str`, `CStr`, `OsStr`,
+  or `Path`.][71447]
+- [`Box<[T]>` now implements `From<[T; N]>`.][71095]
+- [`BitOr` and `BitOrAssign` are implemented for all `NonZero`
+  integer types.][69813]
+- [The `fetch_min`, and `fetch_max` methods have been added to all atomic
+  integer types.][72324]
+- [The `fetch_update` method has been added to all atomic integer types.][71843]
+
+Stabilized APIs
+---------------
+- [`Arc::as_ptr`]
+- [`BTreeMap::remove_entry`]
+- [`Rc::as_ptr`]
+- [`rc::Weak::as_ptr`]
+- [`rc::Weak::from_raw`]
+- [`rc::Weak::into_raw`]
+- [`str::strip_prefix`]
+- [`str::strip_suffix`]
+- [`sync::Weak::as_ptr`]
+- [`sync::Weak::from_raw`]
+- [`sync::Weak::into_raw`]
+- [`char::UNICODE_VERSION`]
+- [`Span::resolved_at`]
+- [`Span::located_at`]
+- [`Span::mixed_site`]
+- [`unix::process::CommandExt::arg0`]
+
+Cargo
+-----
+
+Misc
+----
+- [Rustdoc now supports strikethrough text in Markdown.][71928] E.g.
+  `~~outdated information~~` becomes "~~outdated information~~".
+- [Added an emoji to Rustdoc's deprecated API message.][72014]
+
+Compatibility Notes
+-------------------
+- [Trying to self initialize a static value (that is creating a value using
+  itself) is unsound and now causes a compile error.][71140]
+- [`{f32, f64}::powi` now returns a slightly different value on Windows.][73420]
+  This is due to changes in LLVM's intrinsics which `{f32, f64}::powi` uses.
+- [Rustdoc's CLI's extra error exit codes have been removed.][71900] These were
+  previously undocumented and not intended for public use. Rustdoc still provides
+  a non-zero exit code on errors.
+
+Internals Only
+--------------
+- [Make clippy a git subtree instead of a git submodule][70655]
+- [Unify the undo log of all snapshot types][69464]
+
+[73420]: https://github.com/rust-lang/rust/issues/73420/
+[72324]: https://github.com/rust-lang/rust/pull/72324/
+[71843]: https://github.com/rust-lang/rust/pull/71843/
+[71886]: https://github.com/rust-lang/rust/pull/71886/
+[72234]: https://github.com/rust-lang/rust/pull/72234/
+[72239]: https://github.com/rust-lang/rust/pull/72239/
+[72397]: https://github.com/rust-lang/rust/pull/72397/
+[72413]: https://github.com/rust-lang/rust/pull/72413/
+[72014]: https://github.com/rust-lang/rust/pull/72014/
+[72062]: https://github.com/rust-lang/rust/pull/72062/
+[72094]: https://github.com/rust-lang/rust/pull/72094/
+[72133]: https://github.com/rust-lang/rust/pull/72133/
+[71900]: https://github.com/rust-lang/rust/pull/71900/
+[71928]: https://github.com/rust-lang/rust/pull/71928/
+[71662]: https://github.com/rust-lang/rust/pull/71662/
+[71716]: https://github.com/rust-lang/rust/pull/71716/
+[71447]: https://github.com/rust-lang/rust/pull/71447/
+[71269]: https://github.com/rust-lang/rust/pull/71269/
+[71095]: https://github.com/rust-lang/rust/pull/71095/
+[71140]: https://github.com/rust-lang/rust/pull/71140/
+[70655]: https://github.com/rust-lang/rust/pull/70655/
+[70705]: https://github.com/rust-lang/rust/pull/70705/
+[69984]: https://github.com/rust-lang/rust/pull/69984/
+[69813]: https://github.com/rust-lang/rust/pull/69813/
+[69464]: https://github.com/rust-lang/rust/pull/69464/
+[68717]: https://github.com/rust-lang/rust/pull/68717/
+[`Arc::as_ptr`]: https://doc.rust-lang.org/stable/std/sync/struct.Arc.html#method.as_ptr
+[`BTreeMap::remove_entry`]: https://doc.rust-lang.org/stable/std/collections/struct.BTreeMap.html#method.remove_entry
+[`Rc::as_ptr`]: https://doc.rust-lang.org/stable/std/rc/struct.Rc.html#method.as_ptr
+[`rc::Weak::as_ptr`]: https://doc.rust-lang.org/stable/std/rc/struct.Weak.html#method.as_ptr
+[`rc::Weak::from_raw`]: https://doc.rust-lang.org/stable/std/rc/struct.Weak.html#method.from_raw
+[`rc::Weak::into_raw`]: https://doc.rust-lang.org/stable/std/rc/struct.Weak.html#method.into_raw
+[`sync::Weak::as_ptr`]: https://doc.rust-lang.org/stable/std/sync/struct.Weak.html#method.as_ptr
+[`sync::Weak::from_raw`]: https://doc.rust-lang.org/stable/std/sync/struct.Weak.html#method.from_raw
+[`sync::Weak::into_raw`]: https://doc.rust-lang.org/stable/std/sync/struct.Weak.html#method.into_raw
+[`str::strip_prefix`]: https://doc.rust-lang.org/stable/std/primitive.str.html#method.strip_prefix
+[`str::strip_suffix`]: https://doc.rust-lang.org/stable/std/primitive.str.html#method.strip_suffix
+[`char::UNICODE_VERSION`]: https://doc.rust-lang.org/stable/std/char/constant.UNICODE_VERSION.html
+[`Span::resolved_at`]: https://doc.rust-lang.org/stable/proc_macro/struct.Span.html#method.resolved_at
+[`Span::located_at`]: https://doc.rust-lang.org/stable/proc_macro/struct.Span.html#method.located_at
+[`Span::mixed_site`]: https://doc.rust-lang.org/stable/proc_macro/struct.Span.html#method.mixed_site
+[`unix::process::CommandExt::arg0`]: https://doc.rust-lang.org/std/os/unix/process/trait.CommandExt.html#tymethod.arg0
+
+
+Version 1.44.1 (2020-06-18)
+===========================
+
+* [rustfmt accepts rustfmt_skip in cfg_attr again.][73078]
+* [Don't hash executable filenames on apple platforms, fixing backtraces.][cargo/8329]
+* [Fix crashes when finding backtrace on macOS.][71397]
+* [Clippy applies lint levels into different files.][clippy/5356]
+
+[71397]: https://github.com/rust-lang/rust/issues/71397
+[73078]: https://github.com/rust-lang/rust/issues/73078
+[cargo/8329]: https://github.com/rust-lang/cargo/pull/8329
+[clippy/5356]: https://github.com/rust-lang/rust-clippy/issues/5356
+
+
 Version 1.44.0 (2020-06-04)
 ==========================
 

src/bootstrap/bin/rustc.rs

@@ -76,6 +76,10 @@ fn main() {
         cmd.env("RUST_BACKTRACE", "1");
     }
 
+    if let Ok(lint_flags) = env::var("RUSTC_LINT_FLAGS") {
+        cmd.args(lint_flags.split_whitespace());
+    }
+
     if target.is_some() {
         // The stage0 compiler has a special sysroot distinct from what we
         // actually downloaded, so we just always pass the `--sysroot` option,

src/bootstrap/builder.rs

@@ -1130,22 +1130,32 @@ impl<'a> Builder<'a> {
         cargo.env("RUSTC_VERBOSE", self.verbosity.to_string());
 
         if source_type == SourceType::InTree {
+            let mut lint_flags = Vec::new();
             // When extending this list, add the new lints to the RUSTFLAGS of the
             // build_bootstrap function of src/bootstrap/bootstrap.py as well as
             // some code doesn't go through this `rustc` wrapper.
-            rustflags.arg("-Wrust_2018_idioms");
-            rustflags.arg("-Wunused_lifetimes");
+            lint_flags.push("-Wrust_2018_idioms");
+            lint_flags.push("-Wunused_lifetimes");
 
             if self.config.deny_warnings {
-                rustflags.arg("-Dwarnings");
+                lint_flags.push("-Dwarnings");
             }
 
             // FIXME(#58633) hide "unused attribute" errors in incremental
             // builds of the standard library, as the underlying checks are
             // not yet properly integrated with incremental recompilation.
             if mode == Mode::Std && compiler.stage == 0 && self.config.incremental {
-                rustflags.arg("-Aunused-attributes");
+                lint_flags.push("-Aunused-attributes");
             }
+            // This does not use RUSTFLAGS due to caching issues with Cargo.
+            // Clippy is treated as an "in tree" tool, but shares the same
+            // cache as other "submodule" tools. With these options set in
+            // RUSTFLAGS, that causes *every* shared dependency to be rebuilt.
+            // By injecting this into the rustc wrapper, this circumvents
+            // Cargo's fingerprint detection. This is fine because lint flags
+            // are always ignored in dependencies. Eventually this should be
+            // fixed via better support from Cargo.
+            cargo.env("RUSTC_LINT_FLAGS", lint_flags.join(" "));
         }
 
         if let Mode::Rustc | Mode::Codegen = mode {

src/librustc_error_codes/error_codes.rs

@@ -383,6 +383,7 @@ E0669: include_str!("./error_codes/E0669.md"),
 E0670: include_str!("./error_codes/E0670.md"),
 E0671: include_str!("./error_codes/E0671.md"),
 E0687: include_str!("./error_codes/E0687.md"),
+E0688: include_str!("./error_codes/E0688.md"),
 E0689: include_str!("./error_codes/E0689.md"),
 E0690: include_str!("./error_codes/E0690.md"),
 E0691: include_str!("./error_codes/E0691.md"),
@@ -616,7 +617,6 @@ E0768: include_str!("./error_codes/E0768.md"),
     E0640, // infer outlives requirements
 //  E0645, // trait aliases not finished
     E0667, // `impl Trait` in projections
-    E0688, // in-band lifetimes cannot be mixed with explicit lifetime binders
 //  E0694, // an unknown tool name found in scoped attributes
 //  E0702, // replaced with a generic attribute input check
 //  E0707, // multiple elided lifetimes used in arguments of `async fn`

src/librustc_error_codes/error_codes/E0688.md

@@ -0,0 +1,36 @@
+In-band lifetimes were mixed with explicit lifetime binders.
+
+Erroneous code example:
+
+```compile_fail,E0688
+#![feature(in_band_lifetimes)]
+
+fn foo<'a>(x: &'a u32, y: &'b u32) {}   // error!
+
+struct Foo<'a> { x: &'a u32 }
+
+impl Foo<'a> {
+    fn bar<'b>(x: &'a u32, y: &'b u32, z: &'c u32) {}   // error!
+}
+
+impl<'b> Foo<'a> {  // error!
+    fn baz() {}
+}
+```
+
+In-band lifetimes cannot be mixed with explicit lifetime binders.
+For example:
+
+```
+fn foo<'a, 'b>(x: &'a u32, y: &'b u32) {}   // ok!
+
+struct Foo<'a> { x: &'a u32 }
+
+impl<'a> Foo<'a> {
+    fn bar<'b,'c>(x: &'a u32, y: &'b u32, z: &'c u32) {}    // ok!
+}
+
+impl<'a> Foo<'a> {  // ok!
+    fn baz() {}
+}
+```

src/librustc_error_codes/error_codes/E0718.md

@@ -1,7 +1,6 @@
-This error indicates that a `#[lang = ".."]` attribute was placed
-on the wrong type of item.
+A `#[lang = ".."]` attribute was placed on the wrong item type.
 
-Examples of erroneous code:
+Erroneous code example:
 
 ```compile_fail,E0718
 #![feature(lang_items)]

src/librustdoc/html/render.rs

@@ -42,6 +42,7 @@ use std::str;
 use std::string::ToString;
 use std::sync::Arc;
 
+use itertools::Itertools;
 use rustc_ast_pretty::pprust;
 use rustc_data_structures::flock;
 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
@@ -3170,15 +3171,19 @@ const ALLOWED_ATTRIBUTES: &[Symbol] = &[
 //     bar: usize,
 // }
 fn render_attributes(w: &mut Buffer, it: &clean::Item, top: bool) {
-    let mut attrs = String::new();
-
-    for attr in &it.attrs.other_attrs {
-        if !ALLOWED_ATTRIBUTES.contains(&attr.name_or_empty()) {
-            continue;
-        }
+    let attrs = it
+        .attrs
+        .other_attrs
+        .iter()
+        .filter_map(|attr| {
+            if ALLOWED_ATTRIBUTES.contains(&attr.name_or_empty()) {
+                Some(pprust::attribute_to_string(&attr))
+            } else {
+                None
+            }
+        })
+        .join("\n");
 
-        attrs.push_str(&pprust::attribute_to_string(&attr));
-    }
     if !attrs.is_empty() {
         write!(
             w,

src/librustdoc/passes/collect_intra_doc_links.rs

@@ -799,6 +799,7 @@ impl<'a, 'tcx> DocFolder for LinkCollector<'a, 'tcx> {
 
                     let hir_id = self.cx.tcx.hir().as_local_hir_id(local);
                     if !self.cx.tcx.privacy_access_levels(LOCAL_CRATE).is_exported(hir_id)
+                        && (item.visibility == Visibility::Public)
                         && !self.cx.render_options.document_private
                     {
                         let item_name = item.name.as_deref().unwrap_or("<unknown>");

src/libstd/keyword_docs.rs

@@ -1732,8 +1732,72 @@ mod dyn_keyword {}
 //
 /// The [Rust equivalent of a C-style union][union].
 ///
-/// The documentation for this keyword is [not yet complete]. Pull requests welcome!
+/// A `union` looks like a [`struct`] in terms of declaration, but all of its
+/// fields exist in the same memory, superimposed over one another. For instance,
+/// if we wanted some bits in memory that we sometimes interpret as a `u32` and
+/// sometimes as an `f32`, we could write:
+///
+/// ```rust
+/// union IntOrFloat {
+///     i: u32,
+///     f: f32,
+/// }
+///
+/// let mut u = IntOrFloat { f: 1.0 };
+/// // Reading the fields of an union is always unsafe
+/// assert_eq!(unsafe { u.i }, 1065353216);
+/// // Updating through any of the field will modify all of them
+/// u.i = 1073741824;
+/// assert_eq!(unsafe { u.f }, 2.0);
+/// ```
+///
+/// # Matching on unions
+///
+/// It is possible to use pattern matching on `union`s. A single field name must
+/// be used and it must match the name of one of the `union`'s field.
+/// Like reading from a `union`, pattern matching on a `union` requires `unsafe`.
+///
+/// ```rust
+/// union IntOrFloat {
+///     i: u32,
+///     f: f32,
+/// }
+///
+/// let u = IntOrFloat { f: 1.0 };
+///
+/// unsafe {
+///     match u {
+///         IntOrFloat { i: 10 } => println!("Found exactly ten!"),
+///         // Matching the field `f` provides an `f32`.
+///         IntOrFloat { f } => println!("Found f = {} !", f),
+///     }
+/// }
+/// ```
+///
+/// # References to union fields
+///
+/// All fields in a `union` are all at the same place in memory which means
+/// borrowing one borrows the entire `union`, for the same lifetime:
+///
+/// ```rust,compile_fail,E0502
+/// union IntOrFloat {
+///     i: u32,
+///     f: f32,
+/// }
 ///
+/// let mut u = IntOrFloat { f: 1.0 };
+///
+/// let f = unsafe { &u.f };
+/// // This will not compile because the field has already been borrowed, even
+/// // if only immutably
+/// let i = unsafe { &mut u.i };
+///
+/// *i = 10;
+/// println!("f = {} and i = {}", f, i);
+/// ```
+///
+/// See the [Reference][union] for more informations on `union`s.
+///
+/// [`struct`]: keyword.struct.html
 /// [union]: ../reference/items/unions.html
-/// [not yet complete]: https://github.com/rust-lang/rust/issues/34601
 mod union_keyword {}