Auto merge of #73746 - Manishearth:rollup-80jnynm, r=Manishearth

Rollup of 14 pull requests

Successful merges:

 - #72617 (Add a fast path for `std::thread::panicking`.)
 - #72738 (Self contained linking option)
 - #72770 (Implement mixed script confusable lint.)
 - #73418 (Add unstable `core::mem::variant_count` intrinsic)
 - #73460 (Emit line info for generator variants)
 - #73534 (Provide suggestions for some moved value errors)
 - #73538 (make commented examples use valid syntax, and be more consistent )
 - #73581 (Create 0766 error code)
 - #73619 (Document the mod keyword)
 - #73621 (Document the mut keyword)
 - #73648 (Document the return keyword)
 - #73673 (Fix ptr doc warnings.)
 - #73674 (Tweak binop errors)
 - #73687 (Clean up E0701 explanation)

Failed merges:

 - #73708 (Explain move errors that occur due to method calls involving `self` (take two))

r? @ghost

Cargo.lock

@@ -5405,15 +5405,15 @@ dependencies = [
 
 [[package]]
 name = "unicode-script"
-version = "0.4.0"
+version = "0.5.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5b2c5c29e805da6817f5af6a627d65adb045cebf05cccd5a3493d6109454391c"
+checksum = "58b33414ea8db4b7ea0343548dbdc31d27aef06beacf7044a87e564d9b0feb7d"
 
 [[package]]
 name = "unicode-security"
-version = "0.0.3"
+version = "0.0.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a5f9011bbed9c13372bc8df618b55a38138445199caf3b61d432c6859c36dee0"
+checksum = "5d87c28edc5b263377e448d6cdcb935c06b95413d8013ba6fae470558ccab18f"
 dependencies = [
  "unicode-normalization",
  "unicode-script",

config.toml.example

@@ -118,18 +118,24 @@
 # nightlies are already produced for. The current platform must be able to run
 # binaries of this build triple and the nightly will be used to bootstrap the
 # first compiler.
-#build = "x86_64-unknown-linux-gnu"    # defaults to your host platform
+#
+# Defaults to host platform
+#build = "x86_64-unknown-linux-gnu"
 
 # In addition to the build triple, other triples to produce full compiler
 # toolchains for. Each of these triples will be bootstrapped from the build
 # triple and then will continue to bootstrap themselves. This platform must
 # currently be able to run all of the triples provided here.
-#host = ["x86_64-unknown-linux-gnu"]   # defaults to just the build triple
+#
+# Defaults to just the build triple
+#host = ["x86_64-unknown-linux-gnu"]
 
 # In addition to all host triples, other triples to produce the standard library
 # for. Each host triple will be used to produce a copy of the standard library
 # for each target triple.
-#target = ["x86_64-unknown-linux-gnu"] # defaults to just the build triple
+#
+# Defaults to just the build triple
+#target = ["x86_64-unknown-linux-gnu"]
 
 # Use this directory to store build artifacts.
 # You can use "$ROOT" to indicate the root of the git repository.
@@ -174,7 +180,7 @@
 # Python interpreter to use for various tasks throughout the build, notably
 # rustdoc tests, the lldb python interpreter, and some dist bits and pieces.
 #
-# Defaults to the Python interpreter used to execute x.py.
+# Defaults to the Python interpreter used to execute x.py
 #python = "python"
 
 # Force Cargo to check that Cargo.lock describes the precise dependency
@@ -313,11 +319,15 @@
 
 # Whether or not debug assertions are enabled for the compiler and standard
 # library.
-#debug-assertions = debug
+#
+# Defaults to rust.debug value
+#debug-assertions = false
 
 # Whether or not debug assertions are enabled for the standard library.
 # Overrides the `debug-assertions` option, if defined.
-#debug-assertions-std = debug-assertions
+#
+# Defaults to rust.debug-assertions value
+#debug-assertions-std = false
 
 # Debuginfo level for most of Rust code, corresponds to the `-C debuginfo=N` option of `rustc`.
 # `0` - no debug info
@@ -326,16 +336,24 @@
 # Can be overridden for specific subsets of Rust code (rustc, std or tools).
 # Debuginfo for tests run with compiletest is not controlled by this option
 # and needs to be enabled separately with `debuginfo-level-tests`.
-#debuginfo-level = if debug { 2 } else { 0 }
+#
+# Defaults to 2 if debug is true
+#debuginfo-level = 0
 
 # Debuginfo level for the compiler.
-#debuginfo-level-rustc = debuginfo-level
+#
+# Defaults to rust.debuginfo-level value
+#debuginfo-level-rustc = 0
 
 # Debuginfo level for the standard library.
-#debuginfo-level-std = debuginfo-level
+#
+# Defaults to rust.debuginfo-level value
+#debuginfo-level-std = 0
 
 # Debuginfo level for the tools.
-#debuginfo-level-tools = debuginfo-level
+#
+# Defaults to rust.debuginfo-level value
+#debuginfo-level-tools = 0
 
 # Debuginfo level for the test suites run with compiletest.
 # FIXME(#61117): Some tests fail when this option is enabled.

src/libcore/intrinsics.rs

@@ -1917,6 +1917,15 @@ extern "rust-intrinsic" {
     #[rustc_const_unstable(feature = "const_discriminant", issue = "69821")]
     pub fn discriminant_value<T>(v: &T) -> <T as DiscriminantKind>::Discriminant;
 
+    /// Returns the number of variants of the type `T` cast to a `usize`;
+    /// if `T` has no variants, returns 0. Uninhabited variants will be counted.
+    ///
+    /// The to-be-stabilized version of this intrinsic is
+    /// [`std::mem::variant_count`](../../std/mem/fn.variant_count.html)
+    #[rustc_const_unstable(feature = "variant_count", issue = "73662")]
+    #[cfg(not(bootstrap))]
+    pub fn variant_count<T>() -> usize;
+
     /// Rust's "try catch" construct which invokes the function pointer `try_fn`
     /// with the data pointer `data`.
     ///
@@ -1960,6 +1969,12 @@ extern "rust-intrinsic" {
     pub fn ptr_guaranteed_ne<T>(ptr: *const T, other: *const T) -> bool;
 }
 
+#[rustc_const_unstable(feature = "variant_count", issue = "73662")]
+#[cfg(bootstrap)]
+pub const fn variant_count<T>() -> usize {
+    0
+}
+
 // Some functions are defined here because they accidentally got made
 // available in this module on stable. See <https://github.com/rust-lang/rust/issues/15702>.
 // (`transmute` also falls into this category, but it cannot be wrapped due to the

src/libcore/lib.rs

@@ -124,6 +124,7 @@
 #![feature(unsized_locals)]
 #![feature(untagged_unions)]
 #![feature(unwind_attributes)]
+#![feature(variant_count)]
 #![feature(doc_alias)]
 #![feature(mmx_target_feature)]
 #![feature(tbm_target_feature)]

src/libcore/mem/mod.rs

@@ -999,3 +999,33 @@ impl<T> fmt::Debug for Discriminant<T> {
 pub const fn discriminant<T>(v: &T) -> Discriminant<T> {
     Discriminant(intrinsics::discriminant_value(v))
 }
+
+/// Returns the number of variants in the enum type `T`.
+///
+/// If `T` is not an enum, calling this function will not result in undefined behavior, but the
+/// return value is unspecified. Equally, if `T` is an enum with more variants than `usize::MAX`
+/// the return value is unspecified. Uninhabited variants will be counted.
+///
+/// # Examples
+///
+/// ```
+/// # #![feature(never_type)]
+/// # #![feature(variant_count)]
+///
+/// use std::mem;
+///
+/// enum Void {}
+/// enum Foo { A(&'static str), B(i32), C(i32) }
+///
+/// assert_eq!(mem::variant_count::<Void>(), 0);
+/// assert_eq!(mem::variant_count::<Foo>(), 3);
+///
+/// assert_eq!(mem::variant_count::<Option<!>>(), 2);
+/// assert_eq!(mem::variant_count::<Result<!, !>>(), 2);
+/// ```
+#[inline(always)]
+#[unstable(feature = "variant_count", issue = "73662")]
+#[rustc_const_unstable(feature = "variant_count", issue = "73662")]
+pub const fn variant_count<T>() -> usize {
+    intrinsics::variant_count::<T>()
+}

src/libcore/ptr/const_ptr.rs

@@ -316,7 +316,6 @@ impl<T: ?Sized> *const T {
     /// differently have not been explored. This method should not be used to introduce such
     /// differences, and it should also not be stabilized before we have a better understanding
     /// of this issue.
-    /// ```
     #[unstable(feature = "const_raw_ptr_comparison", issue = "53020")]
     #[rustc_const_unstable(feature = "const_raw_ptr_comparison", issue = "53020")]
     #[inline]
@@ -349,7 +348,6 @@ impl<T: ?Sized> *const T {
     /// differently have not been explored. This method should not be used to introduce such
     /// differences, and it should also not be stabilized before we have a better understanding
     /// of this issue.
-    /// ```
     #[unstable(feature = "const_raw_ptr_comparison", issue = "53020")]
     #[rustc_const_unstable(feature = "const_raw_ptr_comparison", issue = "53020")]
     #[inline]

src/libcore/ptr/mut_ptr.rs

@@ -294,7 +294,6 @@ impl<T: ?Sized> *mut T {
     /// differently have not been explored. This method should not be used to introduce such
     /// differences, and it should also not be stabilized before we have a better understanding
     /// of this issue.
-    /// ```
     #[unstable(feature = "const_raw_ptr_comparison", issue = "53020")]
     #[rustc_const_unstable(feature = "const_raw_ptr_comparison", issue = "53020")]
     #[inline]
@@ -327,7 +326,6 @@ impl<T: ?Sized> *mut T {
     /// differently have not been explored. This method should not be used to introduce such
     /// differences, and it should also not be stabilized before we have a better understanding
     /// of this issue.
-    /// ```
     #[unstable(feature = "const_raw_ptr_comparison", issue = "53020")]
     #[rustc_const_unstable(feature = "const_raw_ptr_comparison", issue = "53020")]
     #[inline]