Rollup of 12 pull requests

Cargo.lock

@@ -36,6 +36,14 @@ dependencies = [
  "url 1.7.2 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "annotate-snippets"
+version = "0.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "ansi_term 0.11.0 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "ansi_term"
 version = "0.11.0"
@@ -2246,7 +2254,7 @@ dependencies = [
  "rustc-serialize 0.3.24 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc-workspace-hack 1.0.0",
  "rustc_tools_util 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "rustfmt-nightly 1.2.0",
+ "rustfmt-nightly 1.2.1",
  "serde 1.0.82 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde_derive 1.0.81 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde_ignored 0.0.4 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -3038,8 +3046,9 @@ dependencies = [
 
 [[package]]
 name = "rustfmt-nightly"
-version = "1.2.0"
+version = "1.2.1"
 dependencies = [
+ "annotate-snippets 0.5.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "atty 0.2.11 (registry+https://github.com/rust-lang/crates.io-index)",
  "bytecount 0.5.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "cargo_metadata 0.7.1 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -3049,6 +3058,7 @@ dependencies = [
  "env_logger 0.6.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "failure 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "getopts 0.2.17 (registry+https://github.com/rust-lang/crates.io-index)",
+ "ignore 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "itertools 0.8.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "lazy_static 1.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -3061,7 +3071,7 @@ dependencies = [
  "serde_derive 1.0.81 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde_json 1.0.33 (registry+https://github.com/rust-lang/crates.io-index)",
  "term 0.5.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "toml 0.4.10 (registry+https://github.com/rust-lang/crates.io-index)",
+ "toml 0.5.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "unicode-segmentation 1.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "unicode-width 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "unicode_categories 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -3987,6 +3997,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum adler32 1.0.3 (registry+https://github.com/rust-lang/crates.io-index)" = "7e522997b529f05601e05166c07ed17789691f562762c7f3b987263d2dedee5c"
 "checksum aho-corasick 0.6.9 (registry+https://github.com/rust-lang/crates.io-index)" = "1e9a933f4e58658d7b12defcf96dc5c720f20832deebe3e0a19efd3b6aaeeb9e"
 "checksum ammonia 1.1.0 (registry+https://github.com/rust-lang/crates.io-index)" = "fd4c682378117e4186a492b2252b9537990e1617f44aed9788b9a1149de45477"
+"checksum annotate-snippets 0.5.0 (registry+https://github.com/rust-lang/crates.io-index)" = "e8bcdcd5b291ce85a78f2b9d082a8de9676c12b1840d386d67bc5eea6f9d2b4e"
 "checksum ansi_term 0.11.0 (registry+https://github.com/rust-lang/crates.io-index)" = "ee49baf6cb617b853aa8d93bf420db2383fab46d314482ca2803b40d5fde979b"
 "checksum arc-swap 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)" = "1025aeae2b664ca0ea726a89d574fe8f4e77dd712d443236ad1de00379450cf6"
 "checksum argon2rs 0.2.5 (registry+https://github.com/rust-lang/crates.io-index)" = "3f67b0b6a86dae6e67ff4ca2b6201396074996379fba2b92ff649126f37cb392"

src/bootstrap/test.rs

@@ -1268,11 +1268,11 @@ impl Step for Compiletest {
         builder.add_rust_test_threads(&mut cmd);
 
         if builder.config.sanitizers {
-            cmd.env("SANITIZER_SUPPORT", "1");
+            cmd.env("RUSTC_SANITIZER_SUPPORT", "1");
         }
 
         if builder.config.profiler {
-            cmd.env("PROFILER_SUPPORT", "1");
+            cmd.env("RUSTC_PROFILER_SUPPORT", "1");
         }
 
         cmd.env("RUST_TEST_TMPDIR", builder.out.join("tmp"));

src/libcore/iter/adapters/mod.rs

@@ -981,6 +981,16 @@ impl<I> DoubleEndedIterator for Enumerate<I> where
         })
     }
 
+    #[inline]
+    fn nth_back(&mut self, n: usize) -> Option<(usize, <I as Iterator>::Item)> {
+        self.iter.nth_back(n).map(|a| {
+            let len = self.iter.len();
+            // Can safely add, `ExactSizeIterator` promises that the number of
+            // elements fits into a `usize`.
+            (self.count + len, a)
+        })
+    }
+
     #[inline]
     fn try_rfold<Acc, Fold, R>(&mut self, init: Acc, mut fold: Fold) -> R where
         Self: Sized, Fold: FnMut(Acc, Self::Item) -> R, R: Try<Ok=Acc>
@@ -1790,6 +1800,17 @@ impl<I> DoubleEndedIterator for Fuse<I> where I: DoubleEndedIterator {
         }
     }
 
+    #[inline]
+    default fn nth_back(&mut self, n: usize) -> Option<<I as Iterator>::Item> {
+        if self.done {
+            None
+        } else {
+            let nth = self.iter.nth_back(n);
+            self.done = nth.is_none();
+            nth
+        }
+    }
+
     #[inline]
     default fn try_rfold<Acc, Fold, R>(&mut self, init: Acc, fold: Fold) -> R where
         Self: Sized, Fold: FnMut(Acc, Self::Item) -> R, R: Try<Ok=Acc>
@@ -1878,6 +1899,11 @@ impl<I> DoubleEndedIterator for Fuse<I>
         self.iter.next_back()
     }
 
+    #[inline]
+    fn nth_back(&mut self, n: usize) -> Option<<I as Iterator>::Item> {
+        self.iter.nth_back(n)
+    }
+
     #[inline]
     fn try_rfold<Acc, Fold, R>(&mut self, init: Acc, fold: Fold) -> R where
         Self: Sized, Fold: FnMut(Acc, Self::Item) -> R, R: Try<Ok=Acc>

src/libcore/slice/mod.rs

@@ -838,7 +838,7 @@ impl<T> [T] {
     }
 
     /// Returns an iterator over `chunk_size` elements of the slice at a time, starting at the
-    /// beginning of the slice.
+    /// end of the slice.
     ///
     /// The chunks are slices and do not overlap. If `chunk_size` does not divide the length of the
     /// slice, then the last up to `chunk_size-1` elements will be omitted and can be retrieved
@@ -849,7 +849,7 @@ impl<T> [T] {
     ///
     /// See [`rchunks`] for a variant of this iterator that also returns the remainder as a smaller
     /// chunk, and [`chunks_exact`] for the same iterator but starting at the beginning of the
-    /// slice of the slice.
+    /// slice.
     ///
     /// # Panics
     ///
@@ -890,7 +890,7 @@ impl<T> [T] {
     ///
     /// See [`rchunks_mut`] for a variant of this iterator that also returns the remainder as a
     /// smaller chunk, and [`chunks_exact_mut`] for the same iterator but starting at the beginning
-    /// of the slice of the slice.
+    /// of the slice.
     ///
     /// # Panics
     ///

src/libcore/str/mod.rs

@@ -795,6 +795,11 @@ impl DoubleEndedIterator for Bytes<'_> {
         self.0.next_back()
     }
 
+    #[inline]
+    fn nth_back(&mut self, n: usize) -> Option<Self::Item> {
+        self.0.nth_back(n)
+    }
+
     #[inline]
     fn rfind<P>(&mut self, predicate: P) -> Option<Self::Item> where
         P: FnMut(&Self::Item) -> bool

src/libcore/tests/iter.rs

@@ -389,6 +389,24 @@ fn test_iterator_enumerate_nth() {
     assert_eq!(i, 3);
 }
 
+#[test]
+fn test_iterator_enumerate_nth_back() {
+    let xs = [0, 1, 2, 3, 4, 5];
+    let mut it = xs.iter().enumerate();
+    while let Some((i, &x)) = it.nth_back(0) {
+        assert_eq!(i, x);
+    }
+
+    let mut it = xs.iter().enumerate();
+    while let Some((i, &x)) = it.nth_back(1) {
+        assert_eq!(i, x);
+    }
+
+    let (i, &x) = xs.iter().enumerate().nth_back(3).unwrap();
+    assert_eq!(i, x);
+    assert_eq!(i, 2);
+}
+
 #[test]
 fn test_iterator_enumerate_count() {
     let xs = [0, 1, 2, 3, 4, 5];

src/librustc/hir/lowering.rs

@@ -4685,6 +4685,14 @@ impl<'a> LoweringContext<'a> {
                         Symbol::intern("try_trait")
                     ].into()),
                 );
+                let try_span = self.sess.source_map().end_point(e.span);
+                let try_span = self.mark_span_with_reason(
+                    CompilerDesugaringKind::QuestionMark,
+                    try_span,
+                    Some(vec![
+                        Symbol::intern("try_trait")
+                    ].into()),
+                );
 
                 // `Try::into_result(<expr>)`
                 let discr = {
@@ -4729,14 +4737,14 @@ impl<'a> LoweringContext<'a> {
                 //              return Try::from_error(From::from(err)),`
                 let err_arm = {
                     let err_ident = self.str_to_ident("err");
-                    let (err_local, err_local_nid) = self.pat_ident(e.span, err_ident);
+                    let (err_local, err_local_nid) = self.pat_ident(try_span, err_ident);
                     let from_expr = {
                         let path = &["convert", "From", "from"];
                         let from = P(self.expr_std_path(
-                                e.span, path, None, ThinVec::new()));
-                        let err_expr = self.expr_ident(e.span, err_ident, err_local_nid);
+                                try_span, path, None, ThinVec::new()));
+                        let err_expr = self.expr_ident(try_span, err_ident, err_local_nid);
 
-                        self.expr_call(e.span, from, hir_vec![err_expr])
+                        self.expr_call(try_span, from, hir_vec![err_expr])
                     };
                     let from_err_expr =
                         self.wrap_in_try_constructor("from_error", from_expr, unstable_span);
@@ -4745,7 +4753,7 @@ impl<'a> LoweringContext<'a> {
                     let ret_expr = if let Some(catch_node) = catch_scope {
                         let target_id = Ok(self.lower_node_id(catch_node).hir_id);
                         P(self.expr(
-                            e.span,
+                            try_span,
                             hir::ExprKind::Break(
                                 hir::Destination {
                                     label: None,
@@ -4756,10 +4764,10 @@ impl<'a> LoweringContext<'a> {
                             thin_attrs,
                         ))
                     } else {
-                        P(self.expr(e.span, hir::ExprKind::Ret(Some(from_err_expr)), thin_attrs))
+                        P(self.expr(try_span, hir::ExprKind::Ret(Some(from_err_expr)), thin_attrs))
                     };
 
-                    let err_pat = self.pat_err(e.span, err_local);
+                    let err_pat = self.pat_err(try_span, err_local);
                     self.arm(hir_vec![err_pat], ret_expr)
                 };
 

src/librustc/session/config.rs

@@ -1467,6 +1467,8 @@ options! {DebuggingOptions, DebuggingSetter, basic_debugging_options,
         "inject the given attribute in the crate"),
     self_profile: bool = (false, parse_bool, [UNTRACKED],
         "run the self profiler and output the raw event data"),
+    self_profile_events: Option<Vec<String>> = (None, parse_opt_comma_list, [UNTRACKED],
+        "specifies which kinds of events get recorded by the self profiler"),
     emit_stack_sizes: bool = (false, parse_bool, [UNTRACKED],
         "emits a section containing stack size metadata"),
     plt: Option<bool> = (None, parse_opt_bool, [TRACKED],

src/librustc/session/mod.rs

@@ -1138,7 +1138,7 @@ fn build_session_(
 ) -> Session {
     let self_profiler =
         if sopts.debugging_opts.self_profile {
-            let profiler = SelfProfiler::new();
+            let profiler = SelfProfiler::new(&sopts.debugging_opts.self_profile_events);
             match profiler {
                 Ok(profiler) => {
                     crate::ty::query::QueryName::register_with_profiler(&profiler);

src/librustc/traits/error_reporting.rs

@@ -638,6 +638,18 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
                         let OnUnimplementedNote { message, label, note }
                             = self.on_unimplemented_note(trait_ref, obligation);
                         let have_alt_message = message.is_some() || label.is_some();
+                        let is_try = self.tcx.sess.source_map().span_to_snippet(span)
+                            .map(|s| &s == "?")
+                            .unwrap_or(false);
+                        let is_from = format!("{}", trait_ref).starts_with("std::convert::From<");
+                        let message = if is_try && is_from {
+                            Some(format!(
+                                "`?` couldn't convert the error to `{}`",
+                                trait_ref.self_ty(),
+                            ))
+                        } else {
+                            message
+                        };
 
                         let mut err = struct_span_err!(
                             self.tcx.sess,