Auto merge of rust-lang#71151 - Dylan-DPC:rollup-6rt4h7b, r=Dylan-DPC

Rollup of 8 pull requests

Successful merges:

 - rust-lang#70657 (Allow `try`-blocks in places where an open delim is expected)
 - rust-lang#70947 (tighten CTFE safety net for accesses to globals)
 - rust-lang#70949 (simplify `vec!` macro)
 - rust-lang#71002 (fix target & runtool args order)
 - rust-lang#71082 (ptr: introduce len() method on raw slices)
 - rust-lang#71128 (Remove unused single_step flag)
 - rust-lang#71133 (Tighten time complexity on the doc of sort_by_key)
 - rust-lang#71135 (Update books)

Failed merges:

r? @ghost

Author: bors

src/doc/book

@@ -42,10 +42,9 @@ macro_rules! vec {
     ($elem:expr; $n:expr) => (
         $crate::vec::from_elem($elem, $n)
     );
-    ($($x:expr),*) => (
-        <[_]>::into_vec(box [$($x),*])
+    ($($x:expr),+ $(,)?) => (
+        <[_]>::into_vec(box [$($x),+])
     );
-    ($($x:expr,)*) => ($crate::vec![$($x),*])
 }
 
 // HACK(japaric): with cfg(test) the inherent `[T]::into_vec` method, which is

src/doc/edition-guide

@@ -254,7 +254,7 @@ impl<T> [T] {
 
     /// Sorts the slice with a key extraction function.
     ///
-    /// This sort is stable (i.e., does not reorder equal elements) and `O(m n log(m n))`
+    /// This sort is stable (i.e., does not reorder equal elements) and `O(m n log n)`
     /// worst-case, where the key function is `O(m)`.
     ///
     /// For expensive key functions (e.g. functions that are not simple property accesses or

src/doc/embedded-book

@@ -706,6 +706,34 @@ impl<T: ?Sized> *const T {
     }
 }
 
+#[cfg(not(bootstrap))]
+#[lang = "const_slice_ptr"]
+impl<T> *const [T] {
+    /// Returns the length of a raw slice.
+    ///
+    /// The returned value is the number of **elements**, not the number of bytes.
+    ///
+    /// This function is safe, even when the raw slice cannot be cast to a slice
+    /// reference because the pointer is null or unaligned.
+    ///
+    /// # Examples
+    ///
+    /// ```rust
+    /// #![feature(slice_ptr_len)]
+    ///
+    /// use std::ptr;
+    ///
+    /// let slice: *const [i8] = ptr::slice_from_raw_parts(ptr::null(), 3);
+    /// assert_eq!(slice.len(), 3);
+    /// ```
+    #[inline]
+    #[unstable(feature = "slice_ptr_len", issue = "71146")]
+    #[rustc_const_unstable(feature = "const_slice_ptr_len", issue = "71146")]
+    pub const fn len(self) -> usize {
+        unsafe { Repr { rust: self }.raw }.len
+    }
+}
+
 // Equality for pointers
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T: ?Sized> PartialEq for *const T {

src/doc/reference

@@ -894,6 +894,34 @@ impl<T: ?Sized> *mut T {
     }
 }
 
+#[cfg(not(bootstrap))]
+#[lang = "mut_slice_ptr"]
+impl<T> *mut [T] {
+    /// Returns the length of a raw slice.
+    ///
+    /// The returned value is the number of **elements**, not the number of bytes.
+    ///
+    /// This function is safe, even when the raw slice cannot be cast to a slice
+    /// reference because the pointer is null or unaligned.
+    ///
+    /// # Examples
+    ///
+    /// ```rust
+    /// #![feature(slice_ptr_len)]
+    ///
+    /// use std::ptr;
+    ///
+    /// let slice: *mut [i8] = ptr::slice_from_raw_parts_mut(ptr::null_mut(), 3);
+    /// assert_eq!(slice.len(), 3);
+    /// ```
+    #[inline]
+    #[unstable(feature = "slice_ptr_len", issue = "71146")]
+    #[rustc_const_unstable(feature = "const_slice_ptr_len", issue = "71146")]
+    pub const fn len(self) -> usize {
+        unsafe { Repr { rust_mut: self }.raw }.len
+    }
+}
+
 // Equality for pointers
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T: ?Sized> PartialEq for *mut T {

src/doc/rust-by-example

@@ -1697,7 +1697,7 @@ impl<T> [T] {
     /// elements.
     ///
     /// This sort is unstable (i.e., may reorder equal elements), in-place
-    /// (i.e., does not allocate), and `O(m n log(m n))` worst-case, where the key function is
+    /// (i.e., does not allocate), and `O(m n log n)` worst-case, where the key function is
     /// `O(m)`.
     ///
     /// # Current implementation

src/liballoc/macros.rs

@@ -507,9 +507,7 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
                 expanded_fragments.push(Vec::new());
             }
             expanded_fragments[depth - 1].push((expn_id, expanded_fragment));
-            if !self.cx.ecfg.single_step {
-                invocations.extend(new_invocations.into_iter().rev());
-            }
+            invocations.extend(new_invocations.into_iter().rev());
         }
 
         self.cx.current_expansion = orig_expansion_data;
@@ -1819,7 +1817,6 @@ pub struct ExpansionConfig<'feat> {
     pub recursion_limit: usize,
     pub trace_mac: bool,
     pub should_test: bool, // If false, strip `#[test]` nodes
-    pub single_step: bool,
     pub keep_macs: bool,
 }
 
@@ -1831,7 +1828,6 @@ impl<'feat> ExpansionConfig<'feat> {
             recursion_limit: 1024,
             trace_mac: false,
             should_test: false,
-            single_step: false,
             keep_macs: false,
         }
     }

src/liballoc/slice.rs

@@ -135,6 +135,8 @@ language_item_table! {
     SliceU8AllocImplItem,        "slice_u8_alloc",     slice_u8_alloc_impl,     Target::Impl;
     ConstPtrImplItem,            "const_ptr",          const_ptr_impl,          Target::Impl;
     MutPtrImplItem,              "mut_ptr",            mut_ptr_impl,            Target::Impl;
+    ConstSlicePtrImplItem,       "const_slice_ptr",    const_slice_ptr_impl,    Target::Impl;
+    MutSlicePtrImplItem,         "mut_slice_ptr",      mut_slice_ptr_impl,      Target::Impl;
     I8ImplItem,                  "i8",                 i8_impl,                 Target::Impl;
     I16ImplItem,                 "i16",                i16_impl,                Target::Impl;
     I32ImplItem,                 "i32",                i32_impl,                Target::Impl;

src/libcore/ptr/const_ptr.rs

@@ -384,7 +384,7 @@ trait UnusedDelimLint {
     fn is_expr_delims_necessary(inner: &ast::Expr, followed_by_block: bool) -> bool {
         followed_by_block
             && match inner.kind {
-                ast::ExprKind::Ret(_) | ast::ExprKind::Break(..) => true,
+                ExprKind::Ret(_) | ExprKind::Break(..) => true,
                 _ => parser::contains_exterior_struct_lit(&inner),
             }
     }

src/libcore/ptr/mut_ptr.rs

@@ -353,15 +353,30 @@ impl<'mir, 'tcx> interpret::Machine<'mir, 'tcx> for CompileTimeInterpreter {
         static_def_id: Option<DefId>,
         is_write: bool,
     ) -> InterpResult<'tcx> {
-        if is_write && allocation.mutability == Mutability::Not {
-            Err(err_ub!(WriteToReadOnly(alloc_id)).into())
-        } else if is_write {
-            Err(ConstEvalErrKind::ModifiedGlobal.into())
-        } else if memory_extra.can_access_statics || static_def_id.is_none() {
-            // `static_def_id.is_none()` indicates this is not a static, but a const or so.
-            Ok(())
+        if is_write {
+            // Write access. These are never allowed, but we give a targeted error message.
+            if allocation.mutability == Mutability::Not {
+                Err(err_ub!(WriteToReadOnly(alloc_id)).into())
+            } else {
+                Err(ConstEvalErrKind::ModifiedGlobal.into())
+            }
         } else {
-            Err(ConstEvalErrKind::ConstAccessesStatic.into())
+            // Read access. These are usually allowed, with some exceptions.
+            if memory_extra.can_access_statics {
+                // Machine configuration allows us read from anything (e.g., `static` initializer).
+                Ok(())
+            } else if static_def_id.is_some() {
+                // Machine configuration does not allow us to read statics
+                // (e.g., `const` initializer).
+                Err(ConstEvalErrKind::ConstAccessesStatic.into())
+            } else {
+                // Immutable global, this read is fine.
+                // But make sure we never accept a read from something mutable, that would be
+                // unsound. The reason is that as the content of this allocation may be different
+                // now and at run-time, so if we permit reading now we might return the wrong value.
+                assert_eq!(allocation.mutability, Mutability::Not);
+                Ok(())
+            }
         }
     }
 }

src/libcore/slice/mod.rs

@@ -1846,11 +1846,9 @@ impl<'a> Parser<'a> {
     }
 
     fn is_try_block(&self) -> bool {
-        self.token.is_keyword(kw::Try) &&
-        self.look_ahead(1, |t| *t == token::OpenDelim(token::Brace)) &&
-        self.token.uninterpolated_span().rust_2018() &&
-        // Prevent `while try {} {}`, `if try {} {} else {}`, etc.
-        !self.restrictions.contains(Restrictions::NO_STRUCT_LITERAL)
+        self.token.is_keyword(kw::Try)
+            && self.look_ahead(1, |t| *t == token::OpenDelim(token::Brace))
+            && self.token.uninterpolated_span().rust_2018()
     }
 
     /// Parses an `async move? {...}` expression.

src/librustc_expand/expand.rs

@@ -649,11 +649,16 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
                 }
             }
             ty::RawPtr(ty::TypeAndMut { ty: _, mutbl }) => {
-                let lang_def_id = match mutbl {
-                    hir::Mutability::Not => lang_items.const_ptr_impl(),
-                    hir::Mutability::Mut => lang_items.mut_ptr_impl(),
+                let (lang_def_id1, lang_def_id2) = match mutbl {
+                    hir::Mutability::Not => {
+                        (lang_items.const_ptr_impl(), lang_items.const_slice_ptr_impl())
+                    }
+                    hir::Mutability::Mut => {
+                        (lang_items.mut_ptr_impl(), lang_items.mut_slice_ptr_impl())
+                    }
                 };
-                self.assemble_inherent_impl_for_primitive(lang_def_id);
+                self.assemble_inherent_impl_for_primitive(lang_def_id1);
+                self.assemble_inherent_impl_for_primitive(lang_def_id2);
             }
             ty::Int(i) => {
                 let lang_def_id = match i {

src/librustc_hir/lang_items.rs

@@ -112,6 +112,30 @@ impl ItemLikeVisitor<'v> for InherentCollect<'tcx> {
                     item.span,
                 );
             }
+            ty::RawPtr(ty::TypeAndMut { ty: inner, mutbl: hir::Mutability::Not })
+                if matches!(inner.kind, ty::Slice(_)) =>
+            {
+                self.check_primitive_impl(
+                    def_id,
+                    lang_items.const_slice_ptr_impl(),
+                    None,
+                    "const_slice_ptr",
+                    "*const [T]",
+                    item.span,
+                );
+            }
+            ty::RawPtr(ty::TypeAndMut { ty: inner, mutbl: hir::Mutability::Mut })
+                if matches!(inner.kind, ty::Slice(_)) =>
+            {
+                self.check_primitive_impl(
+                    def_id,
+                    lang_items.mut_slice_ptr_impl(),
+                    None,
+                    "mut_slice_ptr",
+                    "*mut [T]",
+                    item.span,
+                );
+            }
             ty::RawPtr(ty::TypeAndMut { ty: _, mutbl: hir::Mutability::Not }) => {
                 self.check_primitive_impl(
                     def_id,

src/librustc_lint/unused.rs

@@ -62,6 +62,8 @@ pub fn collect_trait_impls(krate: Crate, cx: &DocContext<'_>) -> Crate {
         lang_items.slice_u8_alloc_impl(),
         lang_items.const_ptr_impl(),
         lang_items.mut_ptr_impl(),
+        lang_items.const_slice_ptr_impl(),
+        lang_items.mut_slice_ptr_impl(),
     ];
 
     for def_id in primitive_impls.iter().filter_map(|&def_id| def_id) {

src/librustc_mir/const_eval/machine.rs

@@ -263,7 +263,12 @@ fn run_test(
     if no_run && !compile_fail {
         compiler.arg("--emit=metadata");
     }
-    compiler.arg("--target").arg(target.to_string());
+    compiler.arg("--target").arg(match target {
+        TargetTriple::TargetTriple(s) => s,
+        TargetTriple::TargetPath(path) => {
+            path.to_str().expect("target path must be valid unicode").to_string()
+        }
+    });
 
     compiler.arg("-");
     compiler.stdin(Stdio::piped());
@@ -312,8 +317,8 @@ fn run_test(
 
     if let Some(tool) = runtool {
         cmd = Command::new(tool);
-        cmd.arg(output_file);
         cmd.args(runtool_args);
+        cmd.arg(output_file);
     } else {
         cmd = Command::new(output_file);
     }

src/librustc_parse/parser/expr.rs

@@ -1,7 +1,11 @@
+// run-pass
 // compile-flags: --edition 2018
 
 #![feature(try_blocks)]
 
 fn main() {
-    match try { false } { _ => {} } //~ ERROR expected expression, found reserved keyword `try`
+    match try { } {
+        Err(()) => (),
+        Ok(()) => (),
+    }
 }

src/librustc_typeck/check/method/probe.rs

@@ -3,5 +3,6 @@
 #![feature(try_blocks)]
 
 fn main() {
-    while try { false } {} //~ ERROR expected expression, found reserved keyword `try`
+    while try { false } {}
+    //~^ ERROR the trait bound `bool: std::ops::Try` is not satisfied
 }

src/librustc_typeck/coherence/inherent_impls.rs

@@ -1,8 +1,11 @@
-error: expected expression, found reserved keyword `try`
-  --> $DIR/try-block-in-while.rs:6:11
+error[E0277]: the trait bound `bool: std::ops::Try` is not satisfied
+  --> $DIR/try-block-in-while.rs:6:15
    |
 LL |     while try { false } {}
-   |           ^^^ expected expression
+   |               ^^^^^^^^^ the trait `std::ops::Try` is not implemented for `bool`
+   |
+   = note: required by `std::ops::Try::from_ok`
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0277`.

src/librustdoc/passes/collect_trait_impls.rs

@@ -0,0 +1,28 @@
+// check-pass
+// compile-flags: --edition 2018
+
+#![feature(try_blocks)]
+#![warn(unused_parens, unused_braces)]
+
+fn consume<T>(_: Result<T, T>) -> T { todo!() }
+
+fn main() {
+    consume((try {}));
+    //~^ WARN unnecessary parentheses
+
+    consume({ try {} });
+    //~^ WARN unnecessary braces
+
+    match (try {}) {
+        //~^ WARN unnecessary parentheses
+        Ok(()) | Err(()) => (),
+    }
+
+    if let Err(()) = (try {}) {}
+    //~^ WARN unnecessary parentheses
+
+    match (try {}) {
+        //~^ WARN unnecessary parentheses
+        Ok(()) | Err(()) => (),
+    }
+}