Rollup of 11 pull requests

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

@@ -355,7 +355,38 @@ $ rustdoc src/lib.rs --edition 2018
 $ rustdoc --test src/lib.rs --edition 2018
 ```
 
-This flag allows rustdoc to treat your rust code as the given edition. It will compile doctests with
+This flag allows `rustdoc` to treat your rust code as the given edition. It will compile doctests with
 the given edition as well. As with `rustc`, the default edition that `rustdoc` will use is `2015`
 (the first edition).
 
+## `--theme`: add a theme to the documentation output
+
+Using this flag looks like this:
+
+```bash
+$ rustdoc src/lib.rs --theme /path/to/your/custom-theme.css
+```
+
+`rustdoc`'s default output includes two themes: `light` (the default) and
+`dark`. This flag allows you to add custom themes to the output. Giving a CSS
+file to this flag adds it to your documentation as an additional theme choice.
+The theme's name is determined by its filename; a theme file named
+`custom-theme.css` will add a theme named `custom-theme` to the documentation.
+
+## `--check-theme`: verify custom themes against the default theme
+
+Using this flag looks like this:
+
+```bash
+$ rustdoc --check-theme /path/to/your/custom-theme.css
+```
+
+While `rustdoc`'s HTML output is more-or-less consistent between versions, there
+is no guarantee that a theme file will have the same effect. The `--theme` flag
+will still allow you to add the theme to your documentation, but to ensure that
+your theme works as expected, you can use this flag to verify that it implements
+the same CSS rules as the official `light` theme.
+
+`--check-theme` is a separate mode in `rustdoc`. When `rustdoc` sees the
+`--check-theme` flag, it discards all other flags and only performs the CSS rule
+comparison operation.

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

@@ -294,30 +294,6 @@ some consideration for their stability, and names that end in a number). Giving
 `rustdoc` will disable this sorting and instead make it print the items in the order they appear in
 the source.
 
-### `--themes`: provide additional themes
-
-Using this flag looks like this:
-
-```bash
-$ rustdoc src/lib.rs -Z unstable-options --themes theme.css
-```
-
-Giving this flag to `rustdoc` will make it copy your theme into the generated crate docs and enable
-it in the theme selector. Note that `rustdoc` will reject your theme file if it doesn't style
-everything the "light" theme does. See `--theme-checker` below for details.
-
-### `--theme-checker`: verify theme CSS for validity
-
-Using this flag looks like this:
-
-```bash
-$ rustdoc -Z unstable-options --theme-checker theme.css
-```
-
-Before including your theme in crate docs, `rustdoc` will compare all the CSS rules it contains
-against the "light" theme included by default. Using this flag will allow you to see which rules are
-missing if `rustdoc` rejects your theme.
-
 ### `--resource-suffix`: modifying the name of CSS/JavaScript in crate docs
 
 Using this flag looks like this:

src/liballoc/vec.rs

@@ -1333,10 +1333,9 @@ impl<T> Vec<T> {
 
     /// Splits the collection into two at the given index.
     ///
-    /// Returns a newly allocated `Self`. `self` contains elements `[0, at)`,
-    /// and the returned `Self` contains elements `[at, len)`.
-    ///
-    /// Note that the capacity of `self` does not change.
+    /// Returns a newly allocated vector containing the elements in the range
+    /// `[at, len)`. After the call, the original vector will be left containing
+    /// the elements `[0, at)` with its previous capacity unchanged.
     ///
     /// # Panics
     ///

src/libcore/macros.rs → src/libcore/macros/mod.rs

@@ -1,6 +1,4 @@
-/// Panics the current thread.
-///
-/// For details, see `std::macros`.
+#[doc(include = "panic.md")]
 #[macro_export]
 #[allow_internal_unstable(core_panic,
     // FIXME(anp, eddyb) `core_intrinsics` is used here to allow calling

src/libcore/macros/panic.md

@@ -0,0 +1,47 @@
+Panics the current thread.
+
+This allows a program to terminate immediately and provide feedback
+to the caller of the program. `panic!` should be used when a program reaches
+an unrecoverable state.
+
+This macro is the perfect way to assert conditions in example code and in
+tests. `panic!` is closely tied with the `unwrap` method of both [`Option`]
+and [`Result`][runwrap] enums. Both implementations call `panic!` when they are set
+to None or Err variants.
+
+This macro is used to inject panic into a Rust thread, causing the thread to
+panic entirely. Each thread's panic can be reaped as the `Box<Any>` type,
+and the single-argument form of the `panic!` macro will be the value which
+is transmitted.
+
+[`Result`] enum is often a better solution for recovering from errors than
+using the `panic!` macro. This macro should be used to avoid proceeding using
+incorrect values, such as from external sources. Detailed information about
+error handling is found in the [book].
+
+The multi-argument form of this macro panics with a string and has the
+[`format!`] syntax for building a string.
+
+See also the macro [`compile_error!`], for raising errors during compilation.
+
+[runwrap]: ../std/result/enum.Result.html#method.unwrap
+[`Option`]: ../std/option/enum.Option.html#method.unwrap
+[`Result`]: ../std/result/enum.Result.html
+[`format!`]: ../std/macro.format.html
+[`compile_error!`]: ../std/macro.compile_error.html
+[book]: ../book/ch09-00-error-handling.html
+
+# Current implementation
+
+If the main thread panics it will terminate all your threads and end your
+program with code `101`.
+
+# Examples
+
+```should_panic
+# #![allow(unreachable_code)]
+panic!();
+panic!("this is a terrible mistake!");
+panic!(4); // panic with the value of 4 to be collected elsewhere
+panic!("this is a {} {message}", "fancy", message = "message");
+```

src/libcore/mem/mod.rs

@@ -744,20 +744,20 @@ pub fn drop<T>(_x: T) { }
 ///     bar: u8,
 /// }
 ///
-/// let foo_slice = [10u8];
+/// let foo_array = [10u8];
 ///
 /// unsafe {
-///     // Copy the data from 'foo_slice' and treat it as a 'Foo'
-///     let mut foo_struct: Foo = mem::transmute_copy(&foo_slice);
+///     // Copy the data from 'foo_array' and treat it as a 'Foo'
+///     let mut foo_struct: Foo = mem::transmute_copy(&foo_array);
 ///     assert_eq!(foo_struct.bar, 10);
 ///
 ///     // Modify the copied data
 ///     foo_struct.bar = 20;
 ///     assert_eq!(foo_struct.bar, 20);
 /// }
 ///
-/// // The contents of 'foo_slice' should not have changed
-/// assert_eq!(foo_slice, [10]);
+/// // The contents of 'foo_array' should not have changed
+/// assert_eq!(foo_array, [10]);
 /// ```
 #[inline]
 #[stable(feature = "rust1", since = "1.0.0")]

src/libpanic_unwind/lib.rs

@@ -39,11 +39,6 @@ cfg_if::cfg_if! {
     if #[cfg(miri)] {
         #[path = "miri.rs"]
         mod imp;
-        // On MSVC we need the SEH lang items as well...
-        // This should match the conditions of the `seh.rs` import below.
-        #[cfg(all(target_env = "msvc", not(target_arch = "aarch64")))]
-        #[allow(unused)]
-        mod seh;
     } else if #[cfg(target_os = "emscripten")] {
         #[path = "emcc.rs"]
         mod imp;

src/libpanic_unwind/miri.rs

@@ -1,3 +1,5 @@
+#![allow(nonstandard_style)]
+
 use core::any::Any;
 use alloc::boxed::Box;
 
@@ -13,11 +15,28 @@ pub unsafe fn cleanup(ptr: *mut u8) -> Box<dyn Any + Send> {
     Box::from_raw(ptr)
 }
 
-
 // This is required by the compiler to exist (e.g., it's a lang item),
 // but is never used by Miri. Therefore, we just use a stub here
 #[lang = "eh_personality"]
 #[cfg(not(test))]
 fn rust_eh_personality() {
     unsafe { core::intrinsics::abort() }
 }
+
+// The rest is required on *some* targets to exist (specifically, MSVC targets that use SEH).
+// We just add it on all targets. Copied from `seh.rs`.
+#[repr(C)]
+pub struct _TypeDescriptor {
+    pub pVFTable: *const u8,
+    pub spare: *mut u8,
+    pub name: [u8; 11],
+}
+
+const TYPE_NAME: [u8; 11] = *b"rust_panic\0";
+
+#[cfg_attr(not(test), lang = "eh_catch_typeinfo")]
+static mut TYPE_DESCRIPTOR: _TypeDescriptor = _TypeDescriptor {
+    pVFTable: core::ptr::null(),
+    spare: core::ptr::null_mut(),
+    name: TYPE_NAME,
+};

src/librustc/hir/def.rs

@@ -42,8 +42,6 @@ pub enum NonMacroAttrKind {
     DeriveHelper,
     /// Single-segment custom attribute registered with `#[register_attr]`.
     Registered,
-    /// Single-segment custom attribute registered by a legacy plugin (`register_attribute`).
-    LegacyPluginHelper,
 }
 
 #[derive(Clone, Copy, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, HashStable)]
@@ -330,7 +328,6 @@ impl NonMacroAttrKind {
             NonMacroAttrKind::Tool => "tool attribute",
             NonMacroAttrKind::DeriveHelper => "derive helper attribute",
             NonMacroAttrKind::Registered => "explicitly registered attribute",
-            NonMacroAttrKind::LegacyPluginHelper => "legacy plugin helper attribute",
         }
     }
 
@@ -345,8 +342,7 @@ impl NonMacroAttrKind {
     pub fn is_used(self) -> bool {
         match self {
             NonMacroAttrKind::Tool | NonMacroAttrKind::DeriveHelper => true,
-            NonMacroAttrKind::Builtin | NonMacroAttrKind::Registered |
-            NonMacroAttrKind::LegacyPluginHelper => false,
+            NonMacroAttrKind::Builtin | NonMacroAttrKind::Registered  => false,
         }
     }
 }

src/librustc/hir/lowering.rs

@@ -1219,7 +1219,7 @@ impl<'a> LoweringContext<'a> {
                                     ImplTraitContext::disallowed(),
                                 ),
                                 unsafety: f.unsafety,
-                                abi: this.lower_abi(f.abi),
+                                abi: this.lower_extern(f.ext),
                                 decl: this.lower_fn_decl(&f.decl, None, false, None),
                                 param_names: this.lower_fn_params_to_names(&f.decl),
                             }))

src/librustc/hir/lowering/item.rs

@@ -735,7 +735,7 @@ impl LoweringContext<'_> {
 
     fn lower_foreign_mod(&mut self, fm: &ForeignMod) -> hir::ForeignMod {
         hir::ForeignMod {
-            abi: self.lower_abi(fm.abi),
+            abi: fm.abi.map_or(abi::Abi::C, |abi| self.lower_abi(abi)),
             items: fm.items
                 .iter()
                 .map(|x| self.lower_foreign_item(x))
@@ -1283,18 +1283,26 @@ impl LoweringContext<'_> {
             unsafety: h.unsafety,
             asyncness: self.lower_asyncness(h.asyncness.node),
             constness: h.constness.node,
-            abi: self.lower_abi(h.abi),
+            abi: self.lower_extern(h.ext),
         }
     }
 
-    pub(super) fn lower_abi(&mut self, abi: Abi) -> abi::Abi {
-        abi::lookup(&abi.symbol.as_str()).unwrap_or_else(|| {
+    pub(super) fn lower_abi(&mut self, abi: StrLit) -> abi::Abi {
+        abi::lookup(&abi.symbol_unescaped.as_str()).unwrap_or_else(|| {
             self.error_on_invalid_abi(abi);
             abi::Abi::Rust
         })
     }
 
-    fn error_on_invalid_abi(&self, abi: Abi) {
+    pub(super) fn lower_extern(&mut self, ext: Extern) -> abi::Abi {
+        match ext {
+            Extern::None => abi::Abi::Rust,
+            Extern::Implicit => abi::Abi::C,
+            Extern::Explicit(abi) => self.lower_abi(abi),
+        }
+    }
+
+    fn error_on_invalid_abi(&self, abi: StrLit) {
         struct_span_err!(
             self.sess,
             abi.span,

src/librustc/session/mod.rs

@@ -21,11 +21,10 @@ use errors::emitter::{Emitter, EmitterWriter};
 use errors::emitter::HumanReadableErrorType;
 use errors::annotate_snippet_emitter_writer::{AnnotateSnippetEmitterWriter};
 use syntax::edition::Edition;
-use syntax::feature_gate::{self, AttributeType};
+use syntax::feature_gate;
 use errors::json::JsonEmitter;
 use syntax::source_map;
 use syntax::sess::{ParseSess, ProcessCfgMod};
-use syntax::symbol::Symbol;
 use syntax_pos::{MultiSpan, Span};
 
 use rustc_target::spec::{PanicStrategy, RelroLevel, Target, TargetTriple};
@@ -79,7 +78,6 @@ pub struct Session {
     /// in order to avoid redundantly verbose output (Issue #24690, #44953).
     pub one_time_diagnostics: Lock<FxHashSet<(DiagnosticMessageId, Option<Span>, String)>>,
     pub plugin_llvm_passes: OneThread<RefCell<Vec<String>>>,
-    pub plugin_attributes: Lock<Vec<(Symbol, AttributeType)>>,
     pub crate_types: Once<Vec<config::CrateType>>,
     /// The `crate_disambiguator` is constructed out of all the `-C metadata`
     /// arguments passed to the compiler. Its value together with the crate-name
@@ -1166,7 +1164,6 @@ fn build_session_(
         working_dir,
         one_time_diagnostics: Default::default(),
         plugin_llvm_passes: OneThread::new(RefCell::new(Vec::new())),
-        plugin_attributes: Lock::new(Vec::new()),
         crate_types: Once::new(),
         crate_disambiguator: Once::new(),
         features: Once::new(),

src/librustc_interface/passes.rs

@@ -240,15 +240,8 @@ pub fn register_plugins<'a>(
         }
     });
 
-    let Registry {
-        syntax_exts,
-        llvm_passes,
-        attributes,
-        ..
-    } = registry;
-
+    let Registry { syntax_exts, llvm_passes, .. } = registry;
     *sess.plugin_llvm_passes.borrow_mut() = llvm_passes;
-    *sess.plugin_attributes.borrow_mut() = attributes;
 
     Ok((krate, PluginInfo { syntax_exts }, Lrc::new(lint_store)))
 }

src/librustc_lint/unused.rs

@@ -309,29 +309,11 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnusedAttributes {
             }
         }
 
-        let plugin_attributes = cx.sess().plugin_attributes.borrow();
-        for &(name, ty) in plugin_attributes.iter() {
-            if ty == AttributeType::Whitelisted && attr.check_name(name) {
-                debug!("{:?} (plugin attr) is whitelisted with ty {:?}", name, ty);
-                break;
-            }
-        }
-
-        let name = attr.name_or_empty();
         if !attr::is_used(attr) {
             debug!("emitting warning for: {:?}", attr);
             cx.span_lint(UNUSED_ATTRIBUTES, attr.span, "unused attribute");
             // Is it a builtin attribute that must be used at the crate level?
-            let known_crate = attr_info.map(|&&(_, ty, ..)| {
-                    ty == AttributeType::CrateLevel
-            }).unwrap_or(false);
-
-            // Has a plugin registered this attribute as one that must be used at
-            // the crate level?
-            let plugin_crate = plugin_attributes.iter()
-                .find(|&&(x, t)| name == x && AttributeType::CrateLevel == t)
-                .is_some();
-            if known_crate || plugin_crate {
+            if attr_info.map_or(false, |(_, ty, ..)| ty == &AttributeType::CrateLevel) {
                 let msg = match attr.style {
                     ast::AttrStyle::Outer => {
                         "crate-level attribute should be an inner attribute: add an exclamation \