Auto merge of #58361 - GuillaumeGomez:rollup, r=GuillaumeGomez

Rollup of 16 pull requests

Successful merges:

 - #57259 (Update reference of rlibc crate to compiler-builtins crate)
 - #57740 (Use `to_ne_bytes` for converting IPv4Addr to octets)
 - #57926 (Tiny expansion to docs for `core::convert`.)
 - #58157 (Add Cargo.lock automatically adding message)
 - #58203 (rustdoc: display sugared return types for async functions)
 - #58243 (Add trait alias support in rustdoc)
 - #58262 (Add #[must_use] message to Fn* traits)
 - #58295 (std::sys::unix::stdio: explain why we do into_raw)
 - #58297 (Cleanup JS a bit)
 - #58317 (Some writing improvement, conciseness of intro)
 - #58324 (miri: give non-generic functions a stable address)
 - #58332 (operand-to-place copies should never be overlapping)
 - #58345 (When there are multiple filenames, print what got interpreted as filenames)
 - #58346 (rpath computation: explain why we pop())
 - #58350 (Fix failing tidy (line endings on Windows))
 - #58352 (miri value visitor: use `?` in macro)

Failed merges:

r? @ghost

Cargo.lock

@@ -1,3 +1,5 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
 [[package]]
 name = "adler32"
 version = "1.0.3"

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

@@ -1,9 +1,8 @@
 # Unstable features
 
 Rustdoc is under active development, and like the Rust compiler, some features are only available
-on the nightly releases. Some of these are new and need some more testing before they're able to get
-released to the world at large, and some of them are tied to features in the Rust compiler that are
-themselves unstable. Several features here require a matching `#![feature(...)]` attribute to
+on nightly releases. Some of these features are new and need some more testing before they're able to be
+released to the world at large, and some of them are tied to features in the Rust compiler that are unstable. Several features here require a matching `#![feature(...)]` attribute to
 enable, and thus are more fully documented in the [Unstable Book]. Those sections will link over
 there as necessary.
 
@@ -428,4 +427,4 @@ $ rustdoc src/lib.rs --test -Z unstable-options --persist-doctests target/rustdo
 
 This flag allows you to keep doctest executables around after they're compiled or run.
 Usually, rustdoc will immediately discard a compiled doctest after it's been tested, but
-with this option, you can keep those binaries around for farther testing.
+with this option, you can keep those binaries around for farther testing.

src/libcore/convert.rs

@@ -17,7 +17,10 @@
 //! [`TryFrom<T>`][`TryFrom`] rather than [`Into<U>`][`Into`] or [`TryInto<U>`][`TryInto`],
 //! as [`From`] and [`TryFrom`] provide greater flexibility and offer
 //! equivalent [`Into`] or [`TryInto`] implementations for free, thanks to a
-//! blanket implementation in the standard library.
+//! blanket implementation in the standard library.  However, there are some cases
+//! where this is not possible, such as creating conversions into a type defined
+//! outside your library, so implementing [`Into`] instead of [`From`] is
+//! sometimes necessary.
 //!
 //! # Generic Implementations
 //!

src/libcore/lib.rs

@@ -24,7 +24,7 @@
 //!   often generated by LLVM. Additionally, this library can make explicit
 //!   calls to these functions. Their signatures are the same as found in C.
 //!   These functions are often provided by the system libc, but can also be
-//!   provided by the [rlibc crate](https://crates.io/crates/rlibc).
+//!   provided by the [compiler-builtins crate](https://crates.io/crates/compiler_builtins).
 //!
 //! * `rust_begin_panic` - This function takes four arguments, a
 //!   `fmt::Arguments`, a `&'static str`, and two `u32`'s. These four arguments

src/libcore/ops/function.rs

@@ -62,7 +62,7 @@
     label="expected an `Fn<{Args}>` closure, found `{Self}`",
 )]
 #[fundamental] // so that regex can rely that `&str: !FnMut`
-#[must_use]
+#[must_use = "closures are lazy and do nothing unless called"]
 pub trait Fn<Args> : FnMut<Args> {
     /// Performs the call operation.
     #[unstable(feature = "fn_traits", issue = "29625")]
@@ -141,7 +141,7 @@ pub trait Fn<Args> : FnMut<Args> {
     label="expected an `FnMut<{Args}>` closure, found `{Self}`",
 )]
 #[fundamental] // so that regex can rely that `&str: !FnMut`
-#[must_use]
+#[must_use = "closures are lazy and do nothing unless called"]
 pub trait FnMut<Args> : FnOnce<Args> {
     /// Performs the call operation.
     #[unstable(feature = "fn_traits", issue = "29625")]
@@ -220,7 +220,7 @@ pub trait FnMut<Args> : FnOnce<Args> {
     label="expected an `FnOnce<{Args}>` closure, found `{Self}`",
 )]
 #[fundamental] // so that regex can rely that `&str: !FnMut`
-#[must_use]
+#[must_use = "closures are lazy and do nothing unless called"]
 pub trait FnOnce<Args> {
     /// The returned type after the call operator is used.
     #[stable(feature = "fn_once_output", since = "1.12.0")]

src/librustc/mir/interpret/mod.rs

@@ -27,7 +27,7 @@ pub use self::pointer::{Pointer, PointerArithmetic};
 use std::fmt;
 use crate::mir;
 use crate::hir::def_id::DefId;
-use crate::ty::{self, TyCtxt, Instance};
+use crate::ty::{self, TyCtxt, Instance, subst::UnpackedKind};
 use crate::ty::layout::{self, Size};
 use std::io;
 use crate::rustc_serialize::{Encoder, Decodable, Encodable};
@@ -318,14 +318,29 @@ impl<'tcx> AllocMap<'tcx> {
         id
     }
 
-    /// Functions cannot be identified by pointers, as asm-equal functions can get deduplicated
-    /// by the linker and functions can be duplicated across crates.
-    /// We thus generate a new `AllocId` for every mention of a function. This means that
-    /// `main as fn() == main as fn()` is false, while `let x = main as fn(); x == x` is true.
     pub fn create_fn_alloc(&mut self, instance: Instance<'tcx>) -> AllocId {
-        let id = self.reserve();
-        self.id_to_kind.insert(id, AllocKind::Function(instance));
-        id
+        // Functions cannot be identified by pointers, as asm-equal functions can get deduplicated
+        // by the linker (we set the "unnamed_addr" attribute for LLVM) and functions can be
+        // duplicated across crates.
+        // We thus generate a new `AllocId` for every mention of a function. This means that
+        // `main as fn() == main as fn()` is false, while `let x = main as fn(); x == x` is true.
+        // However, formatting code relies on function identity (see #58320), so we only do
+        // this for generic functions.  Lifetime parameters are ignored.
+        let is_generic = instance.substs.into_iter().any(|kind| {
+            match kind.unpack() {
+                UnpackedKind::Lifetime(_) => false,
+                _ => true,
+            }
+        });
+        if is_generic {
+            // Get a fresh ID
+            let id = self.reserve();
+            self.id_to_kind.insert(id, AllocKind::Function(instance));
+            id
+        } else {
+            // Deduplicate
+            self.intern(AllocKind::Function(instance))
+        }
     }
 
     /// Returns `None` in case the `AllocId` is dangling. An `EvalContext` can still have a

src/librustc_codegen_llvm/back/rpath.rs

@@ -101,9 +101,9 @@ fn get_rpath_relative_to_output(config: &mut RPathConfig, lib: &Path) -> String
 
     let cwd = env::current_dir().unwrap();
     let mut lib = fs::canonicalize(&cwd.join(lib)).unwrap_or_else(|_| cwd.join(lib));
-    lib.pop();
+    lib.pop(); // strip filename
     let mut output = cwd.join(&config.out_filename);
-    output.pop();
+    output.pop(); // strip filename
     let output = fs::canonicalize(&output).unwrap_or(output);
     let relative = path_relative_from(&lib, &output).unwrap_or_else(||
         panic!("couldn't create relative path from {:?} to {:?}", output, lib));

src/librustc_driver/lib.rs

@@ -838,7 +838,15 @@ impl<'a> CompilerCalls<'a> for RustcDefaultCalls {
                 early_error(sopts.error_format, "no input filename given");
             }
             1 => panic!("make_input should have provided valid inputs"),
-            _ => early_error(sopts.error_format, "multiple input filenames provided"),
+            _ =>
+                early_error(
+                    sopts.error_format,
+                    &format!(
+                        "multiple input filenames provided (first two filenames are `{}` and `{}`)",
+                        matches.free[0],
+                        matches.free[1],
+                    ),
+                )
         }
     }
 

src/librustc_mir/interpret/place.rs

@@ -823,6 +823,8 @@ where
         let src = match self.try_read_immediate(src)? {
             Ok(src_val) => {
                 // Yay, we got a value that we can write directly.
+                // FIXME: Add a check to make sure that if `src` is indirect,
+                // it does not overlap with `dest`.
                 return self.write_immediate_no_validate(src_val, dest);
             }
             Err(mplace) => mplace,
@@ -836,7 +838,8 @@ where
         self.memory.copy(
             src_ptr, src_align,
             dest_ptr, dest_align,
-            dest.layout.size, false
+            dest.layout.size,
+            /*nonoverlapping*/ true,
         )?;
 
         Ok(())

src/librustc_mir/interpret/visitor.rs

@@ -125,14 +125,14 @@ impl<'a, 'mir, 'tcx, M: Machine<'a, 'mir, 'tcx>> Value<'a, 'mir, 'tcx, M>
 }
 
 macro_rules! make_value_visitor {
-    ($visitor_trait_name:ident, $($mutability:ident)*) => {
+    ($visitor_trait_name:ident, $($mutability:ident)?) => {
         // How to traverse a value and what to do when we are at the leaves.
         pub trait $visitor_trait_name<'a, 'mir, 'tcx: 'mir+'a, M: Machine<'a, 'mir, 'tcx>>: Sized {
             type V: Value<'a, 'mir, 'tcx, M>;
 
             /// The visitor must have an `EvalContext` in it.
-            fn ecx(&$($mutability)* self)
-                -> &$($mutability)* EvalContext<'a, 'mir, 'tcx, M>;
+            fn ecx(&$($mutability)? self)
+                -> &$($mutability)? EvalContext<'a, 'mir, 'tcx, M>;
 
             // Recursive actions, ready to be overloaded.
             /// Visit the given value, dispatching as appropriate to more specialized visitors.

src/librustdoc/clean/mod.rs

@@ -517,6 +517,7 @@ pub enum ItemEnum {
     StaticItem(Static),
     ConstantItem(Constant),
     TraitItem(Trait),
+    TraitAliasItem(TraitAlias),
     ImplItem(Impl),
     /// A method signature only. Used for required methods in traits (ie,
     /// non-default-methods).
@@ -554,6 +555,7 @@ impl ItemEnum {
             ItemEnum::TyMethodItem(ref i) => &i.generics,
             ItemEnum::MethodItem(ref i) => &i.generics,
             ItemEnum::ForeignFunctionItem(ref f) => &f.generics,
+            ItemEnum::TraitAliasItem(ref ta) => &ta.generics,
             _ => return None,
         })
     }
@@ -603,6 +605,7 @@ impl Clean<Item> for doctree::Module {
         items.extend(self.impls.iter().flat_map(|x| x.clean(cx)));
         items.extend(self.macros.iter().map(|x| x.clean(cx)));
         items.extend(self.proc_macros.iter().map(|x| x.clean(cx)));
+        items.extend(self.trait_aliases.iter().map(|x| x.clean(cx)));
 
         // determine if we should display the inner contents or
         // the outer `mod` item for the source code.
@@ -1724,6 +1727,30 @@ impl FnDecl {
     pub fn self_type(&self) -> Option<SelfTy> {
         self.inputs.values.get(0).and_then(|v| v.to_self())
     }
+
+    /// Returns the sugared return type for an async function.
+    ///
+    /// For example, if the return type is `impl std::future::Future<Output = i32>`, this function
+    /// will return `i32`.
+    ///
+    /// # Panics
+    ///
+    /// This function will panic if the return type does not match the expected sugaring for async
+    /// functions.
+    pub fn sugared_async_return_type(&self) -> FunctionRetTy {
+        match &self.output {
+            FunctionRetTy::Return(Type::ImplTrait(bounds)) => {
+                match &bounds[0] {
+                    GenericBound::TraitBound(PolyTrait { trait_, .. }, ..) => {
+                        let bindings = trait_.bindings().unwrap();
+                        FunctionRetTy::Return(bindings[0].ty.clone())
+                    }
+                    _ => panic!("unexpected desugaring of async function"),
+                }
+            }
+            _ => panic!("unexpected desugaring of async function"),
+        }
+    }
 }
 
 #[derive(Clone, RustcEncodable, RustcDecodable, PartialEq, Eq, Debug, Hash)]
@@ -1885,13 +1912,38 @@ impl Clean<Item> for doctree::Trait {
                 items: self.items.clean(cx),
                 generics: self.generics.clean(cx),
                 bounds: self.bounds.clean(cx),
-                is_spotlight: is_spotlight,
+                is_spotlight,
                 is_auto: self.is_auto.clean(cx),
             }),
         }
     }
 }
 
+#[derive(Clone, RustcEncodable, RustcDecodable, Debug)]
+pub struct TraitAlias {
+    pub generics: Generics,
+    pub bounds: Vec<GenericBound>,
+}
+
+impl Clean<Item> for doctree::TraitAlias {
+    fn clean(&self, cx: &DocContext) -> Item {
+        let attrs = self.attrs.clean(cx);
+        Item {
+            name: Some(self.name.clean(cx)),
+            attrs,
+            source: self.whence.clean(cx),
+            def_id: cx.tcx.hir().local_def_id(self.id),
+            visibility: self.vis.clean(cx),
+            stability: self.stab.clean(cx),
+            deprecation: self.depr.clean(cx),
+            inner: TraitAliasItem(TraitAlias {
+                generics: self.generics.clean(cx),
+                bounds: self.bounds.clean(cx),
+            }),
+        }
+    }
+}
+
 impl Clean<bool> for hir::IsAuto {
     fn clean(&self, _: &DocContext) -> bool {
         match *self {
@@ -2223,6 +2275,7 @@ pub enum TypeKind {
     Macro,
     Attr,
     Derive,
+    TraitAlias,
 }
 
 pub trait GetDefId {
@@ -2282,6 +2335,21 @@ impl Type {
             _ => None,
         }
     }
+
+    pub fn bindings(&self) -> Option<&[TypeBinding]> {
+        match *self {
+            ResolvedPath { ref path, .. } => {
+                path.segments.last().and_then(|seg| {
+                    if let GenericArgs::AngleBracketed { ref bindings, .. } = seg.args {
+                        Some(&**bindings)
+                    } else {
+                        None
+                    }
+                })
+            }
+            _ => None
+        }
+    }
 }
 
 impl GetDefId for Type {
@@ -3819,10 +3887,9 @@ pub fn register_def(cx: &DocContext, def: Def) -> DefId {
             MacroKind::Derive => (i, TypeKind::Derive),
             MacroKind::ProcMacroStub => unreachable!(),
         },
+        Def::TraitAlias(i) => (i, TypeKind::TraitAlias),
         Def::SelfTy(Some(def_id), _) => (def_id, TypeKind::Trait),
-        Def::SelfTy(_, Some(impl_def_id)) => {
-            return impl_def_id
-        }
+        Def::SelfTy(_, Some(impl_def_id)) => return impl_def_id,
         _ => return def.def_id()
     };
     if did.is_local() { return did }

src/librustdoc/doctree.rs

@@ -38,6 +38,7 @@ pub struct Module {
     pub foreigns: Vec<hir::ForeignMod>,
     pub macros: Vec<Macro>,
     pub proc_macros: Vec<ProcMacro>,
+    pub trait_aliases: Vec<TraitAlias>,
     pub is_crate: bool,
 }
 
@@ -53,21 +54,22 @@ impl Module {
             where_inner: syntax_pos::DUMMY_SP,
             attrs      : hir::HirVec::new(),
             extern_crates: Vec::new(),
-            imports    : Vec::new(),
-            structs    : Vec::new(),
-            unions     : Vec::new(),
-            enums      : Vec::new(),
-            fns        : Vec::new(),
-            mods       : Vec::new(),
-            typedefs   : Vec::new(),
-            existentials: Vec::new(),
-            statics    : Vec::new(),
-            constants  : Vec::new(),
-            traits     : Vec::new(),
-            impls      : Vec::new(),
-            foreigns   : Vec::new(),
-            macros     : Vec::new(),
-            proc_macros: Vec::new(),
+            imports    :   Vec::new(),
+            structs    :   Vec::new(),
+            unions     :   Vec::new(),
+            enums      :   Vec::new(),
+            fns        :   Vec::new(),
+            mods       :   Vec::new(),
+            typedefs   :   Vec::new(),
+            existentials:  Vec::new(),
+            statics    :   Vec::new(),
+            constants  :   Vec::new(),
+            traits     :   Vec::new(),
+            impls      :   Vec::new(),
+            foreigns   :   Vec::new(),
+            macros     :   Vec::new(),
+            proc_macros:   Vec::new(),
+            trait_aliases: Vec::new(),
             is_crate   : false,
         }
     }
@@ -208,6 +210,18 @@ pub struct Trait {
     pub depr: Option<attr::Deprecation>,
 }
 
+pub struct TraitAlias {
+    pub name: Name,
+    pub generics: hir::Generics,
+    pub bounds: hir::HirVec<hir::GenericBound>,
+    pub attrs: hir::HirVec<ast::Attribute>,
+    pub id: ast::NodeId,
+    pub whence: Span,
+    pub vis: hir::Visibility,
+    pub stab: Option<attr::Stability>,
+    pub depr: Option<attr::Deprecation>,
+}
+
 #[derive(Debug)]
 pub struct Impl {
     pub unsafety: hir::Unsafety,