Auto merge of #47962 - kennytm:rollup, r=kennytm

Rollup of 10 pull requests

- Successful merges: #46156, #47829, #47842, #47898, #47914, #47916, #47919, #47942, #47951, #47973
- Failed merges: #47753

src/doc/unstable-book/src/language-features/lang-items.md

@@ -37,28 +37,23 @@ unsafe fn allocate(size: usize, _align: usize) -> *mut u8 {
     p
 }
 
-#[lang = "exchange_free"]
-unsafe fn deallocate(ptr: *mut u8, _size: usize, _align: usize) {
-    libc::free(ptr as *mut libc::c_void)
-}
-
 #[lang = "box_free"]
 unsafe fn box_free<T: ?Sized>(ptr: *mut T) {
-    deallocate(ptr as *mut u8, ::core::mem::size_of_val(&*ptr), ::core::mem::align_of_val(&*ptr));
+    libc::free(ptr as *mut libc::c_void)
 }
 
 #[start]
-fn main(argc: isize, argv: *const *const u8) -> isize {
-    let x = box 1;
+fn main(_argc: isize, _argv: *const *const u8) -> isize {
+    let _x = box 1;
 
     0
 }
 
 #[lang = "eh_personality"] extern fn rust_eh_personality() {}
 #[lang = "panic_fmt"] extern fn rust_begin_panic() -> ! { unsafe { intrinsics::abort() } }
-# #[lang = "eh_unwind_resume"] extern fn rust_eh_unwind_resume() {}
-# #[no_mangle] pub extern fn rust_eh_register_frames () {}
-# #[no_mangle] pub extern fn rust_eh_unregister_frames () {}
+#[lang = "eh_unwind_resume"] extern fn rust_eh_unwind_resume() {}
+#[no_mangle] pub extern fn rust_eh_register_frames () {}
+#[no_mangle] pub extern fn rust_eh_unregister_frames () {}
 ```
 
 Note the use of `abort`: the `exchange_malloc` lang item is assumed to
@@ -80,7 +75,7 @@ Other features provided by lang items include:
 
 Lang items are loaded lazily by the compiler; e.g. if one never uses
 `Box` then there is no need to define functions for `exchange_malloc`
-and `exchange_free`. `rustc` will emit an error when an item is needed
+and `box_free`. `rustc` will emit an error when an item is needed
 but not found in the current crate or any that it depends on.
 
 Most lang items are defined by `libcore`, but if you're trying to build
@@ -318,4 +313,4 @@ the source code.
   - `phantom_data`: `libcore/marker.rs`
   - `freeze`: `libcore/marker.rs`
   - `debug_trait`: `libcore/fmt/mod.rs`
-  - `non_zero`: `libcore/nonzero.rs`
\ No newline at end of file
+  - `non_zero`: `libcore/nonzero.rs`

src/libcore/intrinsics.rs

@@ -992,7 +992,7 @@
     ///         ptr::copy_nonoverlapping(y, x, 1);
     ///         ptr::copy_nonoverlapping(&t, y, 1);
     ///
-    ///         // y and t now point to the same thing, but we need to completely forget `tmp`
+    ///         // y and t now point to the same thing, but we need to completely forget `t`
     ///         // because it's no longer relevant.
     ///         mem::forget(t);
     ///     }

src/libcore/mem.rs

@@ -189,6 +189,7 @@ pub fn forget<T>(t: T) {
 /// Type | size_of::\<Type>()
 /// ---- | ---------------
 /// () | 0
+/// bool | 1
 /// u8 | 1
 /// u16 | 2
 /// u32 | 4

src/libcore/num/f32.rs

@@ -239,7 +239,9 @@ fn powi(self, n: i32) -> f32 {
     /// Converts to degrees, assuming the number is in radians.
     #[inline]
     fn to_degrees(self) -> f32 {
-        self * (180.0f32 / consts::PI)
+        // Use a constant for better precision.
+        const PIS_IN_180: f32 = 57.2957795130823208767981548141051703_f32;
+        self * PIS_IN_180
     }
 
     /// Converts to radians, assuming the number is in degrees.

src/libcore/num/f64.rs

@@ -237,6 +237,9 @@ fn powi(self, n: i32) -> f64 {
     /// Converts to degrees, assuming the number is in radians.
     #[inline]
     fn to_degrees(self) -> f64 {
+        // The division here is correctly rounded with respect to the true
+        // value of 180/π. (This differs from f32, where a constant must be
+        // used to ensure a correctly rounded result.)
         self * (180.0f64 / consts::PI)
     }
 

src/librustc_errors/snippet.rs

@@ -10,32 +10,8 @@
 
 // Code for annotating snippets.
 
-use syntax_pos::{Span, FileMap};
-use CodeMapper;
-use std::rc::Rc;
 use Level;
 
-#[derive(Clone)]
-pub struct SnippetData {
-    codemap: Rc<CodeMapper>,
-    files: Vec<FileInfo>,
-}
-
-#[derive(Clone)]
-pub struct FileInfo {
-    file: Rc<FileMap>,
-
-    /// The "primary file", if any, gets a `-->` marker instead of
-    /// `>>>`, and has a line-number/column printed and not just a
-    /// filename (other files are not guaranteed to have line numbers
-    /// or columns). It appears first in the listing. It is known to
-    /// contain at least one primary span, though primary spans (which
-    /// are designated with `^^^`) may also occur in other files.
-    primary_span: Option<Span>,
-
-    lines: Vec<Line>,
-}
-
 #[derive(Clone, Debug, PartialOrd, Ord, PartialEq, Eq)]
 pub struct Line {
     pub line_index: usize,

src/librustc_mir/dataflow/impls/borrows.rs

@@ -396,8 +396,7 @@ fn statement_effect_on_borrows(&self,
                         // Issue #46746: Two-phase borrows handles
                         // stmts of form `Tmp = &mut Borrow` ...
                         match lhs {
-                            Place::Local(..) => {} // okay
-                            Place::Static(..) => unreachable!(), // (filtered by is_unsafe_place)
+                            Place::Local(..) | Place::Static(..) => {} // okay
                             Place::Projection(..) => {
                                 // ... can assign into projections,
                                 // e.g. `box (&mut _)`. Current

src/librustc_passes/loops.rs

@@ -119,6 +119,11 @@ fn visit_expr(&mut self, e: &'hir hir::Expr) {
                                              kind.name())
                                 .span_label(e.span,
                                             "can only break with a value inside `loop`")
+                                .span_suggestion(e.span,
+                                                 &format!("instead, use `break` on its own \
+                                                           without a value inside this `{}` loop",
+                                                          kind.name()),
+                                                 "break".to_string())
                                 .emit();
                         }
                     }

src/librustdoc/html/static/rustdoc.css

@@ -181,15 +181,19 @@ nav.sub {
 	overflow: auto;
 }
 
-.sidebar .current {
+.sidebar .block > ul > li {
 	margin-right: -20px;
 }
 
-.content, nav { max-width: 960px; }
+.content, nav {
+	max-width: 960px;
+}
 
 /* Everything else */
 
-.js-only, .hidden { display: none !important; }
+.js-only, .hidden {
+	display: none !important;
+}
 
 .sidebar img {
 	margin: 20px auto;
@@ -218,7 +222,9 @@ nav.sub {
 	border: none;
 }
 
-.location a:first-child { font-weight: 500; }
+.location a:first-child {
+	font-weight: 500;
+}
 
 .block {
 	padding: 0;
@@ -299,7 +305,9 @@ nav.sub {
 	-ms-user-select: none;
 	user-select: none;
 }
-.line-numbers span { cursor: pointer; }
+.line-numbers span {
+	cursor: pointer;
+}
 
 .docblock-short p {
 	display: inline;
@@ -317,7 +325,9 @@ nav.sub {
 	text-overflow: ellipsis;
 	margin: 0;
 }
-.docblock-short code { white-space: nowrap; }
+.docblock-short code {
+	white-space: nowrap;
+}
 
 .docblock h1, .docblock h2, .docblock h3, .docblock h4, .docblock h5 {
 	border-bottom: 1px solid;
@@ -384,7 +394,9 @@ h4 > code, h3 > code, .invisible > code {
 	display: inline-block;
 }
 
-#main { position: relative; }
+#main {
+	position: relative;
+}
 #main > .since {
 	top: inherit;
 	font-family: "Fira Sans", "Helvetica Neue", Helvetica, Arial, sans-serif;
@@ -428,7 +440,9 @@ h4 > code, h3 > code, .invisible > code {
 	padding: 0;
 }
 
-.content .item-list li { margin-bottom: 1em; }
+.content .item-list li {
+	margin-bottom: 1em;
+}
 
 .content .multi-column {
 	-moz-column-count: 5;

src/libstd/f32.rs

@@ -1531,6 +1531,7 @@ fn test_to_degrees() {
         assert!(nan.to_degrees().is_nan());
         assert_eq!(inf.to_degrees(), inf);
         assert_eq!(neg_inf.to_degrees(), neg_inf);
+        assert_eq!(1_f32.to_degrees(), 57.2957795130823208767981548141051703);
     }
 
     #[test]

src/libsyntax/parse/lexer/mod.rs

@@ -246,14 +246,27 @@ fn err_span_(&self, from_pos: BytePos, to_pos: BytePos, m: &str) {
         self.err_span(self.mk_sp(from_pos, to_pos), m)
     }
 
+    /// Pushes a character to a message string for error reporting
+    fn push_escaped_char_for_msg(m: &mut String, c: char) {
+        match c {
+            '\u{20}'...'\u{7e}' => {
+                // Don't escape \, ' or " for user-facing messages
+                m.push(c);
+            }
+            _ => {
+                for c in c.escape_default() {
+                    m.push(c);
+                }
+            }
+        }
+    }
+
     /// Report a lexical error spanning [`from_pos`, `to_pos`), appending an
     /// escaped character to the error message
     fn fatal_span_char(&self, from_pos: BytePos, to_pos: BytePos, m: &str, c: char) -> FatalError {
         let mut m = m.to_string();
         m.push_str(": ");
-        for c in c.escape_default() {
-            m.push(c)
-        }
+        Self::push_escaped_char_for_msg(&mut m, c);
         self.fatal_span_(from_pos, to_pos, &m[..])
     }
     fn struct_fatal_span_char(&self,
@@ -264,9 +277,7 @@ fn struct_fatal_span_char(&self,
                               -> DiagnosticBuilder<'a> {
         let mut m = m.to_string();
         m.push_str(": ");
-        for c in c.escape_default() {
-            m.push(c)
-        }
+        Self::push_escaped_char_for_msg(&mut m, c);
         self.sess.span_diagnostic.struct_span_fatal(self.mk_sp(from_pos, to_pos), &m[..])
     }
 
@@ -275,9 +286,7 @@ fn struct_fatal_span_char(&self,
     fn err_span_char(&self, from_pos: BytePos, to_pos: BytePos, m: &str, c: char) {
         let mut m = m.to_string();
         m.push_str(": ");
-        for c in c.escape_default() {
-            m.push(c)
-        }
+        Self::push_escaped_char_for_msg(&mut m, c);
         self.err_span_(from_pos, to_pos, &m[..]);
     }
     fn struct_err_span_char(&self,
@@ -288,9 +297,7 @@ fn struct_err_span_char(&self,
                             -> DiagnosticBuilder<'a> {
         let mut m = m.to_string();
         m.push_str(": ");
-        for c in c.escape_default() {
-            m.push(c)
-        }
+        Self::push_escaped_char_for_msg(&mut m, c);
         self.sess.span_diagnostic.struct_span_err(self.mk_sp(from_pos, to_pos), &m[..])
     }
 

src/libsyntax_pos/lib.rs

@@ -347,13 +347,24 @@ pub fn macro_backtrace(mut self) -> Vec<MacroBacktrace> {
 
     /// Return a `Span` that would enclose both `self` and `end`.
     pub fn to(self, end: Span) -> Span {
-        let span = self.data();
-        let end = end.data();
+        let span_data = self.data();
+        let end_data = end.data();
+        // FIXME(jseyfried): self.ctxt should always equal end.ctxt here (c.f. issue #23480)
+        // Return the macro span on its own to avoid weird diagnostic output. It is preferable to
+        // have an incomplete span than a completely nonsensical one.
+        if span_data.ctxt != end_data.ctxt {
+            if span_data.ctxt == SyntaxContext::empty() {
+                return end;
+            } else if end_data.ctxt == SyntaxContext::empty() {
+                return self;
+            }
+            // both span fall within a macro
+            // FIXME(estebank) check if it is the *same* macro
+        }
         Span::new(
-            cmp::min(span.lo, end.lo),
-            cmp::max(span.hi, end.hi),
-            // FIXME(jseyfried): self.ctxt should always equal end.ctxt here (c.f. issue #23480)
-            if span.ctxt == SyntaxContext::empty() { end.ctxt } else { span.ctxt },
+            cmp::min(span_data.lo, end_data.lo),
+            cmp::max(span_data.hi, end_data.hi),
+            if span_data.ctxt == SyntaxContext::empty() { end_data.ctxt } else { span_data.ctxt },
         )
     }
 

src/test/parse-fail/bad-char-literals.rs

@@ -15,7 +15,7 @@
 fn main() {
     // these literals are just silly.
     ''';
-    //~^ ERROR: character constant must be escaped: \'
+    //~^ ERROR: character constant must be escaped: '
 
     // note that this is a literal "\n" byte
     '

src/test/parse-fail/lex-stray-backslash.rs

+// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// compile-flags: -Z parse-only
+
+\ //~ ERROR: unknown start of token: \

src/test/run-pass/issue-47789.rs

+// Copyright 2018 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+
+#![feature(nll)]
+
+static mut x: &'static u32 = &0;
+
+fn foo() {
+    unsafe { x = &1; }
+}
+
+fn main() { }

src/test/ui/loop-break-value-no-repeat.stderr

@@ -3,6 +3,10 @@ error[E0571]: `break` with value from a `for` loop
    |
 22 |         break 22 //~ ERROR `break` with value from a `for` loop
    |         ^^^^^^^^ can only break with a value inside `loop`
+help: instead, use `break` on its own without a value inside this `for` loop
+   |
+22 |         break //~ ERROR `break` with value from a `for` loop
+   |         ^^^^^
 
 error: aborting due to previous error
 

src/test/ui/macros/span-covering-argument-1.rs

+// Copyright 2018 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+macro_rules! bad {
+    ($s:ident whatever) => {
+        {
+            let $s = 0;
+            *&mut $s = 0;
+            //~^ ERROR cannot borrow immutable local variable `foo` as mutable [E0596]
+        }
+    }
+}
+
+fn main() {
+    bad!(foo whatever);
+}

src/test/ui/macros/span-covering-argument-1.stderr

+error[E0596]: cannot borrow immutable local variable `foo` as mutable
+  --> $DIR/span-covering-argument-1.rs:15:19
+   |
+14 |             let $s = 0;
+   |                 -- consider changing this to `mut $s`
+15 |             *&mut $s = 0;
+   |                   ^^ cannot borrow mutably
+...
+22 |     bad!(foo whatever);
+   |     ------------------- in this macro invocation
+
+error: aborting due to previous error
+

src/test/ui/span/macro-span-replacement.stderr

 warning: struct is never used: `S`
-  --> $DIR/macro-span-replacement.rs:17:9
+  --> $DIR/macro-span-replacement.rs:17:14
    |
 17 |         $b $a; //~ WARN struct is never used
-   |         ^^^^^^
+   |              ^
 ...
 22 |     m!(S struct);
    |     ------------- in this macro invocation