Auto merge of #60877 - Centril:rollup-j0o5mo5, r=Centril

Rollup of 6 pull requests

Successful merges:

 - #59825 (string: implement From<&String> for String)
 - #59923 (Fix convert module's documentation links)
 - #60691 (Include expression to wait for to the span of Await)
 - #60769 (Update rustc book CLI docs.)
 - #60816 (README.md: Mention MSVC 2017+, not 2013(!))
 - #60851 (Move `box` from the stable keyword to unstable keywords list)

Failed merges:

r? @ghost

README.md

@@ -128,9 +128,15 @@ build.
 #### MSVC
 [windows-msvc]: #windows-msvc
 
-MSVC builds of Rust additionally require an installation of Visual Studio 2013
-(or later) so `rustc` can use its linker. Make sure to check the “C++ tools”
-option.
+MSVC builds of Rust additionally require an installation of Visual Studio 2017
+(or later) so `rustc` can use its linker.  The simplest way is to get the
+[Visual Studio Build Tools] and check the “C++ build tools” workload.
+
+[Visual Studio Build Tools]: https://visualstudio.microsoft.com/downloads/#build-tools-for-visual-studio-2019
+
+At last check (cmake 3.14.3 and msvc 16.0.3) using the 2019 tools fails to
+build the in-tree LLVM build with a CMake error, so use 2017 instead by
+including the “MSVC v141 – VS 2017 C++ x64/x86 build tools (v14.16)” component.
 
 With these dependencies installed, you can build the compiler in a `cmd.exe`
 shell with:

src/doc/rustc/src/command-line-arguments.md

@@ -17,28 +17,147 @@ to `#[cfg(verbose)]` and `#[cfg(feature = "serde")]` respectively.
 
 ## `-L`: add a directory to the library search path
 
-When looking for external crates, a directory passed to this flag will be searched.
+When looking for external crates or libraries, a directory passed to this flag
+will be searched.
+
+The kind of search path can optionally be specified with the form `-L
+KIND=PATH` where `KIND` may be one of:
+
+- `dependency` — Only search for transitive dependencies in this directory.
+- `crate` — Only search for this crate's direct dependencies in this
+  directory.
+- `native` — Only search for native libraries in this directory.
+- `framework` — Only search for macOS frameworks in this directory.
+- `all` — Search for all library kinds in this directory. This is the default
+  if `KIND` is not specified.
 
 ## `-l`: link the generated crate to a native library
 
 This flag allows you to specify linking to a specific native library when building
 a crate.
 
+The kind of library can optionally be specified with the form `-l KIND=lib`
+where `KIND` may be one of:
+
+- `dylib` — A native dynamic library.
+- `static` — A native static library (such as a `.a` archive).
+- `framework` — A macOS framework.
+
+The kind of library can be specified in a [`#[link]`
+attribute][link-attribute]. If the kind is not specified in the `link`
+attribute or on the command-line, it will link a dynamic library if available,
+otherwise it will use a static library. If the kind is specified on the
+command-line, it will override the kind specified in a `link` attribute.
+
+The name used in a `link` attribute may be overridden using the form `-l
+ATTR_NAME:LINK_NAME` where `ATTR_NAME` is the name in the `link` attribute,
+and `LINK_NAME` is the name of the actual library that will be linked.
+
+[link-attribute]: ../reference/items/external-blocks.html#the-link-attribute
+
 ## `--crate-type`: a list of types of crates for the compiler to emit
 
-This instructs `rustc` on which crate type to build.
+This instructs `rustc` on which crate type to build. This flag accepts a
+comma-separated list of values, and may be specified multiple times. The valid
+crate types are:
+
+- `lib` — Generates a library kind preferred by the compiler, currently
+  defaults to `rlib`.
+- `rlib` — A Rust static library.
+- `staticlib` — A native static library.
+- `dylib` — A Rust dynamic library.
+- `cdylib` — A native dynamic library.
+- `bin` — A runnable executable program.
+- `proc-macro` — Generates a format suitable for a procedural macro library
+  that may be loaded by the compiler.
+
+The crate type may be specified with the [`crate_type` attribute][crate_type].
+The `--crate-type` command-line value will override the `crate_type`
+attribute.
+
+More details may be found in the [linkage chapter] of the reference.
+
+[linkage chapter]: ../reference/linkage.html
+[crate_type]: ../reference/linkage.html
 
 ## `--crate-name`: specify the name of the crate being built
 
 This informs `rustc` of the name of your crate.
 
-## `--emit`: emit output other than a crate
-
-Instead of producing a crate, this flag can print out things like the assembly or LLVM-IR.
+## `--edition`: specify the edition to use
+
+This flag takes a value of `2015` or `2018`. The default is `2015`. More
+information about editions may be found in the [edition guide].
+
+[edition guide]: ../edition-guide/introduction.html
+
+## `--emit`: specifies the types of output files to generate
+
+This flag controls the types of output files generated by the compiler. It
+accepts a comma-separated list of values, and may be specified multiple times.
+The valid emit kinds are:
+
+- `asm` — Generates a file with the crate's assembly code. The default output
+  filename is `CRATE_NAME.s`.
+- `dep-info` — Generates a file with Makefile syntax that indicates all the
+  source files that were loaded to generate the crate. The default output
+  filename is `CRATE_NAME.d`.
+- `link` — Generates the crates specified by `--crate-type`. The default
+  output filenames depend on the crate type and platform. This is the default
+  if `--emit` is not specified.
+- `llvm-bc` — Generates a binary file containing the [LLVM bitcode]. The
+  default output filename is `CRATE_NAME.bc`.
+- `llvm-ir` — Generates a file containing [LLVM IR]. The default output
+  filename is `CRATE_NAME.ll`.
+- `metadata` — Generates a file containing metadata about the crate. The
+  default output filename is `CRATE_NAME.rmeta`.
+- `mir` — Generates a file containing rustc's mid-level intermediate
+  representation. The default output filename is `CRATE_NAME.mir`.
+- `obj` — Generates a native object file. The default output filename is
+  `CRATE_NAME.o`.
+
+The output filename can be set with the `-o` flag. A suffix may be added to
+the filename with the `-C extra-filename` flag. The files are written to the
+current directory unless the `--out-dir` flag is used. Each emission type may
+also specify the output filename with the form `KIND=PATH`, which takes
+precedence over the `-o` flag.
+
+[LLVM bitcode]: https://llvm.org/docs/BitCodeFormat.html
+[LLVM IR]: https://llvm.org/docs/LangRef.html
 
 ## `--print`: print compiler information
 
-This flag prints out various information about the compiler.
+This flag prints out various information about the compiler. This flag may be
+specified multiple times, and the information is printed in the order the
+flags are specified. Specifying a `--print` flag will usually disable the
+`--emit` step and will only print the requested information. The valid types
+of print values are:
+
+- `crate-name` — The name of the crate.
+- `file-names` — The names of the files created by the `link` emit kind.
+- `sysroot` — Path to the sysroot.
+- `cfg` — List of cfg values. See [conditional compilation] for more
+  information about cfg values.
+- `target-list` — List of known targets. The target may be selected with the
+  `--target` flag.
+- `target-cpus` — List of available CPU values for the current target. The
+  target CPU may be selected with the `-C target-cpu=val` flag.
+- `target-features` — List of available target features for the current
+  target. Target features may be enabled with the `-C target-feature=val`
+  flag.
+- `relocation-models` — List of relocation models. Relocation models may be
+  selected with the `-C relocation-model=val` flag.
+- `code-models` — List of code models. Code models may be selected with the
+  `-C code-model=val` flag.
+- `tls-models` — List of Thread Local Storage models supported. The model may
+  be selected with the `-Z tls-model=val` flag.
+- `native-static-libs` — This may be used when creating a `staticlib` crate
+  type. If this is the only flag, it will perform a full compilation and
+  include a diagnostic note that indicates the linker flags to use when
+  linking the resulting static library. The note starts with the text
+  `native-static-libs:` to make it easier to fetch the output.
+
+[conditional compilation]: ../reference/conditional-compilation.html
 
 ## `-g`: include debug information
 
@@ -54,7 +173,8 @@ This flag controls the output filename.
 
 ## `--out-dir`: directory to write the output in
 
-The outputted crate will be written to this directory.
+The outputted crate will be written to this directory. This flag is ignored if
+the `-o` flag is used.
 
 ## `--explain`: provide a detailed explanation of an error message
 
@@ -111,8 +231,9 @@ This flag, when combined with other flags, makes them produce extra output.
 
 ## `--extern`: specify where an external library is located
 
-This flag allows you to pass the name and location of an external crate that will
-be linked into the crate you're buildling.
+This flag allows you to pass the name and location of an external crate that
+will be linked into the crate you are building. This flag may be specified
+multiple times. The format of the value should be `CRATENAME=PATH`.
 
 ## `--sysroot`: Override the system root
 
@@ -121,8 +242,32 @@ distribution; this flag allows that to be overridden.
 
 ## `--error-format`: control how errors are produced
 
-This flag lets you control the format of errors.
+This flag lets you control the format of messages. Messages are printed to
+stderr. The valid options are:
+
+- `human` — Human-readable output. This is the default.
+- `json` — Structured JSON output.
+- `short` — Short, one-line messages.
 
 ## `--color`: configure coloring of output
 
-This flag lets you control color settings of the output.
+This flag lets you control color settings of the output. The valid options
+are:
+
+- `auto` — Use colors if output goes to a tty. This is the default.
+- `always` — Always use colors.
+- `never` — Never colorize output.
+
+## `--remap-path-prefix`: remap source names in output
+
+Remap source path prefixes in all output, including compiler diagnostics,
+debug information, macro expansions, etc. It takes a value of the form
+`FROM=TO` where a path prefix equal to `FROM` is rewritten to the value `TO`.
+The `FROM` may itself contain an `=` symbol, but the `TO` value may not. This
+flag may be specified multiple times.
+
+This is useful for normalizing build products, for example by removing the
+current directory out of pathnames emitted into the object files. The
+replacement is purely textual, with no consideration of the current system's
+pathname syntax. For example `--remap-path-prefix foo=bar` will match
+`foo/lib.rs` but not `./foo/lib.rs`.

src/liballoc/string.rs

@@ -2189,6 +2189,14 @@ impl From<&str> for String {
     }
 }
 
+#[stable(feature = "from_ref_string", since = "1.35.0")]
+impl From<&String> for String {
+    #[inline]
+    fn from(s: &String) -> String {
+        s.clone()
+    }
+}
+
 // note: test pulls in libstd, which causes errors here
 #[cfg(not(test))]
 #[stable(feature = "string_from_box", since = "1.18.0")]

src/libcore/convert.rs

@@ -104,7 +104,6 @@ pub const fn identity<T>(x: T) -> T { x }
 /// If you need to do a costly conversion it is better to implement [`From`] with type
 /// `&T` or write a custom function.
 ///
-///
 /// `AsRef` has the same signature as [`Borrow`], but `Borrow` is different in few aspects:
 ///
 /// - Unlike `AsRef`, `Borrow` has a blanket impl for any `T`, and can be used to accept either
@@ -133,7 +132,7 @@ pub const fn identity<T>(x: T) -> T { x }
 /// converted a the specified type `T`.
 ///
 /// For example: By creating a generic function that takes an `AsRef<str>` we express that we
-/// want to accept all references that can be converted to &str as an argument.
+/// want to accept all references that can be converted to `&str` as an argument.
 /// Since both [`String`] and `&str` implement `AsRef<str>` we can accept both as input argument.
 ///
 /// [`String`]: ../../std/string/struct.String.html
@@ -149,7 +148,6 @@ pub const fn identity<T>(x: T) -> T { x }
 /// let s = "hello".to_string();
 /// is_hello(s);
 /// ```
-///
 #[stable(feature = "rust1", since = "1.0.0")]
 pub trait AsRef<T: ?Sized> {
     /// Performs the conversion.
@@ -182,6 +180,7 @@ pub trait AsRef<T: ?Sized> {
 /// write a function `add_one`that takes all arguments that can be converted to `&mut u64`.
 /// Because [`Box<T>`] implements `AsMut<T>` `add_one` accepts arguments of type
 /// `&mut Box<u64>` as well:
+///
 /// ```
 /// fn add_one<T: AsMut<u64>>(num: &mut T) {
 ///     *num.as_mut() += 1;
@@ -191,8 +190,8 @@ pub trait AsRef<T: ?Sized> {
 /// add_one(&mut boxed_num);
 /// assert_eq!(*boxed_num, 1);
 /// ```
-/// [`Box<T>`]: ../../std/boxed/struct.Box.html
 ///
+/// [`Box<T>`]: ../../std/boxed/struct.Box.html
 #[stable(feature = "rust1", since = "1.0.0")]
 pub trait AsMut<T: ?Sized> {
     /// Performs the conversion.
@@ -203,18 +202,18 @@ pub trait AsMut<T: ?Sized> {
 /// A value-to-value conversion that consumes the input value. The
 /// opposite of [`From`].
 ///
-/// One should only implement [`Into`] if a conversion to a type outside the current crate is
-/// required. Otherwise one should always prefer implementing [`From`] over [`Into`] because
-/// implementing [`From`] automatically provides one with a implementation of [`Into`] thanks to
+/// One should only implement `Into` if a conversion to a type outside the current crate is
+/// required. Otherwise one should always prefer implementing [`From`] over `Into` because
+/// implementing [`From`] automatically provides one with a implementation of `Into` thanks to
 /// the blanket implementation in the standard library. [`From`] cannot do these type of
 /// conversions because of Rust's orphaning rules.
 ///
 /// **Note: This trait must not fail**. If the conversion can fail, use [`TryInto`].
 ///
 /// # Generic Implementations
 ///
-/// - [`From<T>`]` for U` implies `Into<U> for T`
-/// - [`Into`]` is reflexive, which means that `Into<T> for T` is implemented
+/// - [`From`]`<T> for U` implies `Into<U> for T`
+/// - `Into` is reflexive, which means that `Into<T> for T` is implemented
 ///
 /// # Implementing `Into` for conversions to external types
 ///
@@ -273,7 +272,7 @@ pub trait AsMut<T: ?Sized> {
 /// [`Option<T>`]: ../../std/option/enum.Option.html
 /// [`Result<T, E>`]: ../../std/result/enum.Result.html
 /// [`String`]: ../../std/string/struct.String.html
-/// [From]: trait.From.html
+/// [`From`]: trait.From.html
 /// [`into`]: trait.Into.html#tymethod.into
 #[stable(feature = "rust1", since = "1.0.0")]
 pub trait Into<T>: Sized {
@@ -285,18 +284,18 @@ pub trait Into<T>: Sized {
 /// Used to do value-to-value conversions while consuming the input value. It is the reciprocal of
 /// [`Into`].
 ///
-/// One should always prefer implementing [`From`] over [`Into`]
-/// because implementing [`From`] automatically provides one with a implementation of [`Into`]
+/// One should always prefer implementing `From` over [`Into`]
+/// because implementing `From` automatically provides one with a implementation of [`Into`]
 /// thanks to the blanket implementation in the standard library.
 ///
 /// Only implement [`Into`] if a conversion to a type outside the current crate is required.
-/// [`From`] cannot do these type of conversions because of Rust's orphaning rules.
+/// `From` cannot do these type of conversions because of Rust's orphaning rules.
 /// See [`Into`] for more details.
 ///
-/// Prefer using [`Into`] over using [`From`] when specifying trait bounds on a generic function.
+/// Prefer using [`Into`] over using `From` when specifying trait bounds on a generic function.
 /// This way, types that directly implement [`Into`] can be used as arguments as well.
 ///
-/// The [`From`] is also very useful when performing error handling. When constructing a function
+/// The `From` is also very useful when performing error handling. When constructing a function
 /// that is capable of failing, the return type will generally be of the form `Result<T, E>`.
 /// The `From` trait simplifies error handling by allowing a function to return a single error type
 /// that encapsulate multiple error types. See the "Examples" section and [the book][book] for more
@@ -306,14 +305,15 @@ pub trait Into<T>: Sized {
 ///
 /// # Generic Implementations
 ///
-/// - [`From<T>`]` for U` implies [`Into<U>`]` for T`
-/// - [`From`] is reflexive, which means that `From<T> for T` is implemented
+/// - `From<T> for U` implies [`Into`]`<U> for T`
+/// - `From` is reflexive, which means that `From<T> for T` is implemented
 ///
 /// # Examples
 ///
 /// [`String`] implements `From<&str>`:
 ///
-/// An explicit conversion from a &str to a String is done as follows:
+/// An explicit conversion from a `&str` to a String is done as follows:
+///
 /// ```
 /// let string = "hello".to_string();
 /// let other_string = String::from("hello");
@@ -361,7 +361,7 @@ pub trait Into<T>: Sized {
 /// [`Option<T>`]: ../../std/option/enum.Option.html
 /// [`Result<T, E>`]: ../../std/result/enum.Result.html
 /// [`String`]: ../../std/string/struct.String.html
-/// [`Into<U>`]: trait.Into.html
+/// [`Into`]: trait.Into.html
 /// [`from`]: trait.From.html#tymethod.from
 /// [book]: ../../book/ch09-00-error-handling.html
 #[stable(feature = "rust1", since = "1.0.0")]
@@ -422,7 +422,7 @@ pub trait TryInto<T>: Sized {
 ///
 /// # Generic Implementations
 ///
-/// - `TryFrom<T> for U` implies [`TryInto<U>`]` for T`
+/// - `TryFrom<T> for U` implies [`TryInto`]`<U> for T`
 /// - [`try_from`] is reflexive, which means that `TryFrom<T> for T`
 /// is implemented and cannot fail -- the associated `Error` type for
 /// calling `T::try_from()` on a value of type `T` is `Infallible`.

src/librustc/session/config.rs

@@ -1744,8 +1744,7 @@ pub fn rustc_short_optgroups() -> Vec<RustcOptGroup> {
         opt::multi_s(
             "",
             "print",
-            "Comma separated list of compiler information to \
-             print on stdout",
+            "Compiler information to print on stdout",
             "[crate-name|file-names|sysroot|cfg|target-list|\
              target-cpus|target-features|relocation-models|\
              code-models|tls-models|target-spec-json|native-static-libs]",

src/libsyntax/parse/parser.rs

@@ -2635,6 +2635,7 @@ impl<'a> Parser<'a> {
                     self.expect(&token::OpenDelim(token::Paren))?;
                     let expr = self.parse_expr()?;
                     self.expect(&token::CloseDelim(token::Paren))?;
+                    hi = self.prev_span;
                     ex = ExprKind::Await(ast::AwaitOrigin::MacroLike, expr);
                 } else if self.token.is_path_start() {
                     let path = self.parse_path(PathStyle::Expr)?;