Rollup of 8 pull requests

src/bootstrap/bootstrap.py

@@ -314,7 +314,6 @@ def __init__(self):
         self.build_dir = os.path.join(os.getcwd(), "build")
         self.clean = False
         self.config_toml = ''
-        self.printed = False
         self.rust_root = os.path.abspath(os.path.join(__file__, '../../..'))
         self.use_locked_deps = ''
         self.use_vendored_sources = ''
@@ -336,7 +335,6 @@ def download_stage0(self):
         if self.rustc().startswith(self.bin_root()) and \
                 (not os.path.exists(self.rustc()) or
                  self.program_out_of_date(self.rustc_stamp())):
-            self.print_what_bootstrap_means()
             if os.path.exists(self.bin_root()):
                 shutil.rmtree(self.bin_root())
             filename = "rust-std-{}-{}.tar.gz".format(
@@ -354,7 +352,6 @@ def download_stage0(self):
         if self.cargo().startswith(self.bin_root()) and \
                 (not os.path.exists(self.cargo()) or
                  self.program_out_of_date(self.cargo_stamp())):
-            self.print_what_bootstrap_means()
             filename = "cargo-{}-{}.tar.gz".format(cargo_channel, self.build)
             self._download_stage0_helper(filename, "cargo")
             self.fix_executable("{}/bin/cargo".format(self.bin_root()))
@@ -555,23 +552,6 @@ def exe_suffix():
             return '.exe'
         return ''
 
-    def print_what_bootstrap_means(self):
-        """Prints more information about the build system"""
-        if hasattr(self, 'printed'):
-            return
-        self.printed = True
-        if os.path.exists(self.bootstrap_binary()):
-            return
-        if '--help' not in sys.argv or len(sys.argv) == 1:
-            return
-
-        print('info: the build system for Rust is written in Rust, so this')
-        print('      script is now going to download a stage0 rust compiler')
-        print('      and then compile the build system itself')
-        print('')
-        print('info: in the meantime you can read more about rustbuild at')
-        print('      src/bootstrap/README.md before the download finishes')
-
     def bootstrap_binary(self):
         """Return the path of the boostrap binary
 
@@ -585,7 +565,6 @@ def bootstrap_binary(self):
 
     def build_bootstrap(self):
         """Build bootstrap"""
-        self.print_what_bootstrap_means()
         build_dir = os.path.join(self.build_dir, "bootstrap")
         if self.clean and os.path.exists(build_dir):
             shutil.rmtree(build_dir)
@@ -670,8 +649,16 @@ def set_dev_environment(self):
         self._download_url = 'https://dev-static.rust-lang.org'
 
 
-def bootstrap():
+def bootstrap(help_triggered):
     """Configure, fetch, build and run the initial bootstrap"""
+
+    # If the user is asking for help, let them know that the whole download-and-build
+    # process has to happen before anything is printed out.
+    if help_triggered:
+        print("info: Downloading and building bootstrap before processing --help")
+        print("      command. See src/bootstrap/README.md for help with common")
+        print("      commands.")
+
     parser = argparse.ArgumentParser(description='Build rust')
     parser.add_argument('--config')
     parser.add_argument('--build')
@@ -708,7 +695,7 @@ def bootstrap():
             print('      and so in order to preserve your $HOME this will now')
             print('      use vendored sources by default. Note that if this')
             print('      does not work you should run a normal build first')
-            print('      before running a command like `sudo make install`')
+            print('      before running a command like `sudo ./x.py install`')
 
     if build.use_vendored_sources:
         if not os.path.exists('.cargo'):
@@ -734,7 +721,10 @@ def bootstrap():
     if 'dev' in data:
         build.set_dev_environment()
 
-    build.update_submodules()
+    # No help text depends on submodules. This check saves ~1 minute of git commands, even if
+    # all the submodules are present and downloaded!
+    if not help_triggered:
+        build.update_submodules()
 
     # Fetch/build the bootstrap
     build.build = args.build or build.build_triple()
@@ -760,7 +750,7 @@ def main():
     help_triggered = (
         '-h' in sys.argv) or ('--help' in sys.argv) or (len(sys.argv) == 1)
     try:
-        bootstrap()
+        bootstrap(help_triggered)
         if not help_triggered:
             print("Build completed successfully in {}".format(
                 format_build_time(time() - start_time)))

src/bootstrap/doc.rs

@@ -312,6 +312,7 @@ fn invoke_rustdoc(builder: &Builder, compiler: Compiler, target: Interned<String
     cmd.arg("--html-after-content").arg(&footer)
         .arg("--html-before-content").arg(&version_info)
         .arg("--html-in-header").arg(&favicon)
+        .arg("--markdown-no-toc")
         .arg("--markdown-playground-url")
         .arg("https://play.rust-lang.org/")
         .arg("-o").arg(&out)

src/libcore/benches/iter.rs

@@ -281,3 +281,32 @@ bench_sums! {
     bench_take_while_chain_ref_sum,
     (0i64..1000000).chain(1000000..).take_while(|&x| x < 1111111)
 }
+
+// Checks whether Skip<Zip<A,B>> is as fast as Zip<Skip<A>, Skip<B>>, from
+// https://users.rust-lang.org/t/performance-difference-between-iterator-zip-and-skip-order/15743
+#[bench]
+fn bench_zip_then_skip(b: &mut Bencher) {
+    let v: Vec<_> = (0..100_000).collect();
+    let t: Vec<_> = (0..100_000).collect();
+
+    b.iter(|| {
+        let s = v.iter().zip(t.iter()).skip(10000)
+            .take_while(|t| *t.0 < 10100)
+            .map(|(a, b)| *a + *b)
+            .sum::<u64>();
+        assert_eq!(s, 2009900);
+    });
+}
+#[bench]
+fn bench_skip_then_zip(b: &mut Bencher) {
+    let v: Vec<_> = (0..100_000).collect();
+    let t: Vec<_> = (0..100_000).collect();
+
+    b.iter(|| {
+        let s = v.iter().skip(10000).zip(t.iter().skip(10000))
+            .take_while(|t| *t.0 < 10100)
+            .map(|(a, b)| *a + *b)
+            .sum::<u64>();
+        assert_eq!(s, 2009900);
+    });
+}

src/libcore/iter/mod.rs

@@ -1045,6 +1045,11 @@ impl<A, B> Iterator for Zip<A, B> where A: Iterator, B: Iterator
     fn size_hint(&self) -> (usize, Option<usize>) {
         ZipImpl::size_hint(self)
     }
+
+    #[inline]
+    fn nth(&mut self, n: usize) -> Option<Self::Item> {
+        ZipImpl::nth(self, n)
+    }
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
@@ -1065,6 +1070,14 @@ trait ZipImpl<A, B> {
     fn new(a: A, b: B) -> Self;
     fn next(&mut self) -> Option<Self::Item>;
     fn size_hint(&self) -> (usize, Option<usize>);
+    fn nth(&mut self, n: usize) -> Option<Self::Item>;
+    fn super_nth(&mut self, mut n: usize) -> Option<Self::Item> {
+        while let Some(x) = self.next() {
+            if n == 0 { return Some(x) }
+            n -= 1;
+        }
+        None
+    }
     fn next_back(&mut self) -> Option<Self::Item>
         where A: DoubleEndedIterator + ExactSizeIterator,
               B: DoubleEndedIterator + ExactSizeIterator;
@@ -1094,6 +1107,11 @@ impl<A, B> ZipImpl<A, B> for Zip<A, B>
         })
     }
 
+    #[inline]
+    default fn nth(&mut self, n: usize) -> Option<Self::Item> {
+        self.super_nth(n)
+    }
+
     #[inline]
     default fn next_back(&mut self) -> Option<(A::Item, B::Item)>
         where A: DoubleEndedIterator + ExactSizeIterator,
@@ -1174,6 +1192,24 @@ impl<A, B> ZipImpl<A, B> for Zip<A, B>
         (len, Some(len))
     }
 
+    #[inline]
+    fn nth(&mut self, n: usize) -> Option<Self::Item> {
+        let delta = cmp::min(n, self.len - self.index);
+        let end = self.index + delta;
+        while self.index < end {
+            let i = self.index;
+            self.index += 1;
+            if A::may_have_side_effect() {
+                unsafe { self.a.get_unchecked(i); }
+            }
+            if B::may_have_side_effect() {
+                unsafe { self.b.get_unchecked(i); }
+            }
+        }
+
+        self.super_nth(n - delta)
+    }
+
     #[inline]
     fn next_back(&mut self) -> Option<(A::Item, B::Item)>
         where A: DoubleEndedIterator + ExactSizeIterator,

src/libcore/tests/iter.rs

@@ -144,6 +144,43 @@ fn test_iterator_chain_find() {
     assert_eq!(iter.next(), None);
 }
 
+#[test]
+fn test_zip_nth() {
+    let xs = [0, 1, 2, 4, 5];
+    let ys = [10, 11, 12];
+
+    let mut it = xs.iter().zip(&ys);
+    assert_eq!(it.nth(0), Some((&0, &10)));
+    assert_eq!(it.nth(1), Some((&2, &12)));
+    assert_eq!(it.nth(0), None);
+
+    let mut it = xs.iter().zip(&ys);
+    assert_eq!(it.nth(3), None);
+
+    let mut it = ys.iter().zip(&xs);
+    assert_eq!(it.nth(3), None);
+}
+
+#[test]
+fn test_zip_nth_side_effects() {
+    let mut a = Vec::new();
+    let mut b = Vec::new();
+    let value = [1, 2, 3, 4, 5, 6].iter().cloned()
+        .map(|n| {
+            a.push(n);
+            n * 10
+        })
+        .zip([2, 3, 4, 5, 6, 7, 8].iter().cloned().map(|n| {
+            b.push(n * 100);
+            n * 1000
+        }))
+        .skip(1)
+        .nth(3);
+    assert_eq!(value, Some((50, 6000)));
+    assert_eq!(a, vec![1, 2, 3, 4, 5]);
+    assert_eq!(b, vec![200, 300, 400, 500, 600]);
+}
+
 #[test]
 fn test_iterator_step_by() {
     // Identity

src/librustc/dep_graph/debug.rs

@@ -54,7 +54,7 @@ pub struct EdgeFilter {
 }
 
 impl EdgeFilter {
-    pub fn new(test: &str) -> Result<EdgeFilter, Box<Error>> {
+    pub fn new(test: &str) -> Result<EdgeFilter, Box<dyn Error>> {
         let parts: Vec<_> = test.split("->").collect();
         if parts.len() != 2 {
             Err(format!("expected a filter like `a&b -> c&d`, not `{}`", test).into())

src/librustc/hir/lowering.rs

@@ -80,13 +80,13 @@ pub struct LoweringContext<'a> {
     // Use to assign ids to hir nodes that do not directly correspond to an ast node
     sess: &'a Session,
 
-    cstore: &'a CrateStore,
+    cstore: &'a dyn CrateStore,
 
     // As we walk the AST we must keep track of the current 'parent' def id (in
     // the form of a DefIndex) so that if we create a new node which introduces
     // a definition, then we can properly create the def id.
     parent_def: Option<DefIndex>,
-    resolver: &'a mut Resolver,
+    resolver: &'a mut dyn Resolver,
     name_map: FxHashMap<Ident, Name>,
 
     /// The items being lowered are collected here.
@@ -177,10 +177,10 @@ enum ImplTraitContext {
 }
 
 pub fn lower_crate(sess: &Session,
-                   cstore: &CrateStore,
+                   cstore: &dyn CrateStore,
                    dep_graph: &DepGraph,
                    krate: &Crate,
-                   resolver: &mut Resolver)
+                   resolver: &mut dyn Resolver)
                    -> hir::Crate {
     // We're constructing the HIR here; we don't care what we will
     // read, since we haven't even constructed the *input* to

src/librustc/hir/map/collector.rs

@@ -123,7 +123,7 @@ impl<'a, 'hir> NodeCollector<'a, 'hir> {
 
     pub(super) fn finalize_and_compute_crate_hash(self,
                                                   crate_disambiguator: CrateDisambiguator,
-                                                  cstore: &CrateStore,
+                                                  cstore: &dyn CrateStore,
                                                   codemap: &CodeMap,
                                                   commandline_args_hash: u64)
                                                   -> (Vec<MapEntry<'hir>>, Svh) {

src/librustc/hir/map/def_collector.rs

@@ -26,7 +26,7 @@ pub struct DefCollector<'a> {
     definitions: &'a mut Definitions,
     parent_def: Option<DefIndex>,
     expansion: Mark,
-    pub visit_macro_invoc: Option<&'a mut FnMut(MacroInvocationData)>,
+    pub visit_macro_invoc: Option<&'a mut dyn FnMut(MacroInvocationData)>,
 }
 
 pub struct MacroInvocationData {

src/librustc/hir/map/mod.rs

@@ -19,6 +19,8 @@ use dep_graph::{DepGraph, DepNode, DepKind, DepNodeIndex};
 
 use hir::def_id::{CRATE_DEF_INDEX, DefId, LocalDefId, DefIndexAddressSpace};
 
+use middle::cstore::CrateStore;
+
 use syntax::abi::Abi;
 use syntax::ast::{self, Name, NodeId, CRATE_NODE_ID};
 use syntax::codemap::Spanned;
@@ -1136,8 +1138,9 @@ impl Named for StructField { fn name(&self) -> Name { self.name } }
 impl Named for TraitItem { fn name(&self) -> Name { self.name } }
 impl Named for ImplItem { fn name(&self) -> Name { self.name } }
 
+
 pub fn map_crate<'hir>(sess: &::session::Session,
-                       cstore: &::middle::cstore::CrateStore,
+                       cstore: &dyn CrateStore,
                        forest: &'hir mut Forest,
                        definitions: &'hir Definitions)
                        -> Map<'hir> {

src/librustc/hir/print.rs

@@ -62,7 +62,7 @@ pub trait PpAnn {
 
 pub struct NoAnn;
 impl PpAnn for NoAnn {}
-pub const NO_ANN: &'static PpAnn = &NoAnn;
+pub const NO_ANN: &'static dyn PpAnn = &NoAnn;
 
 impl PpAnn for hir::Crate {
     fn nested(&self, state: &mut State, nested: Nested) -> io::Result<()> {
@@ -83,7 +83,7 @@ pub struct State<'a> {
     literals: Peekable<vec::IntoIter<comments::Literal>>,
     cur_cmnt: usize,
     boxes: Vec<pp::Breaks>,
-    ann: &'a (PpAnn + 'a),
+    ann: &'a (dyn PpAnn + 'a),
 }
 
 impl<'a> PrintState<'a> for State<'a> {
@@ -126,9 +126,9 @@ pub fn print_crate<'a>(cm: &'a CodeMap,
                        sess: &ParseSess,
                        krate: &hir::Crate,
                        filename: FileName,
-                       input: &mut Read,
-                       out: Box<Write + 'a>,
-                       ann: &'a PpAnn,
+                       input: &mut dyn Read,
+                       out: Box<dyn Write + 'a>,
+                       ann: &'a dyn PpAnn,
                        is_expanded: bool)
                        -> io::Result<()> {
     let mut s = State::new_from_input(cm, sess, filename, input, out, ann, is_expanded);
@@ -145,9 +145,9 @@ impl<'a> State<'a> {
     pub fn new_from_input(cm: &'a CodeMap,
                           sess: &ParseSess,
                           filename: FileName,
-                          input: &mut Read,
-                          out: Box<Write + 'a>,
-                          ann: &'a PpAnn,
+                          input: &mut dyn Read,
+                          out: Box<dyn Write + 'a>,
+                          ann: &'a dyn PpAnn,
                           is_expanded: bool)
                           -> State<'a> {
         let (cmnts, lits) = comments::gather_comments_and_literals(sess, filename, input);
@@ -167,8 +167,8 @@ impl<'a> State<'a> {
     }
 
     pub fn new(cm: &'a CodeMap,
-               out: Box<Write + 'a>,
-               ann: &'a PpAnn,
+               out: Box<dyn Write + 'a>,
+               ann: &'a dyn PpAnn,
                comments: Option<Vec<comments::Comment>>,
                literals: Option<Vec<comments::Literal>>)
                -> State<'a> {
@@ -184,7 +184,7 @@ impl<'a> State<'a> {
     }
 }
 
-pub fn to_string<F>(ann: &PpAnn, f: F) -> String
+pub fn to_string<F>(ann: &dyn PpAnn, f: F) -> String
     where F: FnOnce(&mut State) -> io::Result<()>
 {
     let mut wr = Vec::new();