Auto merge of rust-lang#41643 - frewsxcv:rollup, r=frewsxcv

Rollup of 6 pull requests

- Successful merges: rust-lang#41449, rust-lang#41509, rust-lang#41608, rust-lang#41613, rust-lang#41636, rust-lang#41637
- Failed merges:

src/bootstrap/check.rs

@@ -577,6 +577,7 @@ pub fn distcheck(build: &Build) {
         return
     }
 
+    println!("Distcheck");
     let dir = build.out.join("tmp").join("distcheck");
     let _ = fs::remove_dir_all(&dir);
     t!(fs::create_dir_all(&dir));
@@ -594,6 +595,26 @@ pub fn distcheck(build: &Build) {
     build.run(Command::new(build_helper::make(&build.config.build))
                      .arg("check")
                      .current_dir(&dir));
+
+    // Now make sure that rust-src has all of libstd's dependencies
+    println!("Distcheck rust-src");
+    let dir = build.out.join("tmp").join("distcheck-src");
+    let _ = fs::remove_dir_all(&dir);
+    t!(fs::create_dir_all(&dir));
+
+    let mut cmd = Command::new("tar");
+    cmd.arg("-xzf")
+       .arg(dist::rust_src_installer(build))
+       .arg("--strip-components=1")
+       .current_dir(&dir);
+    build.run(&mut cmd);
+
+    let toml = dir.join("rust-src/lib/rustlib/src/rust/src/libstd/Cargo.toml");
+    build.run(Command::new(&build.cargo)
+                     .arg("generate-lockfile")
+                     .arg("--manifest-path")
+                     .arg(&toml)
+                     .current_dir(&dir));
 }
 
 /// Test the build system itself

src/bootstrap/dist.rs

@@ -315,11 +315,18 @@ pub fn std(build: &Build, compiler: &Compiler, target: &str) {
     t!(fs::remove_dir_all(&image));
 }
 
+/// The path to the complete rustc-src tarball
 pub fn rust_src_location(build: &Build) -> PathBuf {
     let plain_name = format!("rustc-{}-src", build.rust_package_vers());
     distdir(build).join(&format!("{}.tar.gz", plain_name))
 }
 
+/// The path to the rust-src component installer
+pub fn rust_src_installer(build: &Build) -> PathBuf {
+    let name = pkgname(build, "rust-src");
+    distdir(build).join(&format!("{}.tar.gz", name))
+}
+
 /// Creates a tarball of save-analysis metadata, if available.
 pub fn analysis(build: &Build, compiler: &Compiler, target: &str) {
     assert!(build.config.extended);

src/libcollections/string.rs

@@ -1604,6 +1604,15 @@ impl FromIterator<String> for String {
     }
 }
 
+#[stable(feature = "herd_cows", since = "1.19.0")]
+impl<'a> FromIterator<Cow<'a, str>> for String {
+    fn from_iter<I: IntoIterator<Item = Cow<'a, str>>>(iter: I) -> String {
+        let mut buf = String::new();
+        buf.extend(iter);
+        buf
+    }
+}
+
 #[stable(feature = "rust1", since = "1.0.0")]
 impl Extend<char> for String {
     fn extend<I: IntoIterator<Item = char>>(&mut self, iter: I) {
@@ -1641,6 +1650,15 @@ impl Extend<String> for String {
     }
 }
 
+#[stable(feature = "herd_cows", since = "1.19.0")]
+impl<'a> Extend<Cow<'a, str>> for String {
+    fn extend<I: IntoIterator<Item = Cow<'a, str>>>(&mut self, iter: I) {
+        for s in iter {
+            self.push_str(&s)
+        }
+    }
+}
+
 /// A convenience impl that delegates to the impl for `&str`
 #[unstable(feature = "pattern",
            reason = "API not fully fleshed out and ready to be stabilized",

src/libcore/benches/num/flt2dec/mod.rs

@@ -13,6 +13,10 @@ mod strategy {
     mod grisu;
 }
 
+use std::f64;
+use std::io::Write;
+use std::vec::Vec;
+use test::Bencher;
 use core::num::flt2dec::{decode, DecodableFloat, FullDecoded, Decoded};
 use core::num::flt2dec::MAX_SIG_DIGITS;
 
@@ -22,3 +26,23 @@ pub fn decode_finite<T: DecodableFloat>(v: T) -> Decoded {
         full_decoded => panic!("expected finite, got {:?} instead", full_decoded)
     }
 }
+
+#[bench]
+fn bench_small_shortest(b: &mut Bencher) {
+    let mut buf = Vec::with_capacity(20);
+
+    b.iter(|| {
+        buf.clear();
+        write!(&mut buf, "{}", 3.1415926f64).unwrap()
+    });
+}
+
+#[bench]
+fn bench_big_shortest(b: &mut Bencher) {
+    let mut buf = Vec::with_capacity(300);
+
+    b.iter(|| {
+        buf.clear();
+        write!(&mut buf, "{}", f64::MAX).unwrap()
+    });
+}

src/libcore/fmt/float.rs

@@ -9,8 +9,43 @@
 // except according to those terms.
 
 use fmt::{Formatter, Result, LowerExp, UpperExp, Display, Debug};
+use mem;
 use num::flt2dec;
 
+// Don't inline this so callers don't use the stack space this function
+// requires unless they have to.
+#[inline(never)]
+fn float_to_decimal_common_exact<T>(fmt: &mut Formatter, num: &T,
+                                    sign: flt2dec::Sign, precision: usize) -> Result
+    where T: flt2dec::DecodableFloat
+{
+    unsafe {
+        let mut buf: [u8; 1024] = mem::uninitialized(); // enough for f32 and f64
+        let mut parts: [flt2dec::Part; 5] = mem::uninitialized();
+        let formatted = flt2dec::to_exact_fixed_str(flt2dec::strategy::grisu::format_exact,
+                                                    *num, sign, precision,
+                                                    false, &mut buf, &mut parts);
+        fmt.pad_formatted_parts(&formatted)
+    }
+}
+
+// Don't inline this so callers that call both this and the above won't wind
+// up using the combined stack space of both functions in some cases.
+#[inline(never)]
+fn float_to_decimal_common_shortest<T>(fmt: &mut Formatter,
+                                       num: &T, sign: flt2dec::Sign) -> Result
+    where T: flt2dec::DecodableFloat
+{
+    unsafe {
+        // enough for f32 and f64
+        let mut buf: [u8; flt2dec::MAX_SIG_DIGITS] = mem::uninitialized();
+        let mut parts: [flt2dec::Part; 5] = mem::uninitialized();
+        let formatted = flt2dec::to_shortest_str(flt2dec::strategy::grisu::format_shortest,
+                                                 *num, sign, 0, false, &mut buf, &mut parts);
+        fmt.pad_formatted_parts(&formatted)
+    }
+}
+
 // Common code of floating point Debug and Display.
 fn float_to_decimal_common<T>(fmt: &mut Formatter, num: &T, negative_zero: bool) -> Result
     where T: flt2dec::DecodableFloat
@@ -23,16 +58,48 @@ fn float_to_decimal_common<T>(fmt: &mut Formatter, num: &T, negative_zero: bool)
         (true,  true)  => flt2dec::Sign::MinusPlusRaw,
     };
 
-    let mut buf = [0; 1024]; // enough for f32 and f64
-    let mut parts = [flt2dec::Part::Zero(0); 16];
-    let formatted = if let Some(precision) = fmt.precision {
-        flt2dec::to_exact_fixed_str(flt2dec::strategy::grisu::format_exact, *num, sign,
-                                    precision, false, &mut buf, &mut parts)
+    if let Some(precision) = fmt.precision {
+        float_to_decimal_common_exact(fmt, num, sign, precision)
     } else {
-        flt2dec::to_shortest_str(flt2dec::strategy::grisu::format_shortest, *num, sign,
-                                 0, false, &mut buf, &mut parts)
-    };
-    fmt.pad_formatted_parts(&formatted)
+        float_to_decimal_common_shortest(fmt, num, sign)
+    }
+}
+
+// Don't inline this so callers don't use the stack space this function
+// requires unless they have to.
+#[inline(never)]
+fn float_to_exponential_common_exact<T>(fmt: &mut Formatter, num: &T,
+                                        sign: flt2dec::Sign, precision: usize,
+                                        upper: bool) -> Result
+    where T: flt2dec::DecodableFloat
+{
+    unsafe {
+        let mut buf: [u8; 1024] = mem::uninitialized(); // enough for f32 and f64
+        let mut parts: [flt2dec::Part; 7] = mem::uninitialized();
+        let formatted = flt2dec::to_exact_exp_str(flt2dec::strategy::grisu::format_exact,
+                                                  *num, sign, precision,
+                                                  upper, &mut buf, &mut parts);
+        fmt.pad_formatted_parts(&formatted)
+    }
+}
+
+// Don't inline this so callers that call both this and the above won't wind
+// up using the combined stack space of both functions in some cases.
+#[inline(never)]
+fn float_to_exponential_common_shortest<T>(fmt: &mut Formatter,
+                                           num: &T, sign: flt2dec::Sign,
+                                           upper: bool) -> Result
+    where T: flt2dec::DecodableFloat
+{
+    unsafe {
+        // enough for f32 and f64
+        let mut buf: [u8; flt2dec::MAX_SIG_DIGITS] = mem::uninitialized();
+        let mut parts: [flt2dec::Part; 7] = mem::uninitialized();
+        let formatted = flt2dec::to_shortest_exp_str(flt2dec::strategy::grisu::format_shortest,
+                                                     *num, sign, (0, 0), upper,
+                                                     &mut buf, &mut parts);
+        fmt.pad_formatted_parts(&formatted)
+    }
 }
 
 // Common code of floating point LowerExp and UpperExp.
@@ -45,17 +112,12 @@ fn float_to_exponential_common<T>(fmt: &mut Formatter, num: &T, upper: bool) ->
         true  => flt2dec::Sign::MinusPlus,
     };
 
-    let mut buf = [0; 1024]; // enough for f32 and f64
-    let mut parts = [flt2dec::Part::Zero(0); 16];
-    let formatted = if let Some(precision) = fmt.precision {
+    if let Some(precision) = fmt.precision {
         // 1 integral digit + `precision` fractional digits = `precision + 1` total digits
-        flt2dec::to_exact_exp_str(flt2dec::strategy::grisu::format_exact, *num, sign,
-                                  precision + 1, upper, &mut buf, &mut parts)
+        float_to_exponential_common_exact(fmt, num, sign, precision + 1, upper)
     } else {
-        flt2dec::to_shortest_exp_str(flt2dec::strategy::grisu::format_shortest, *num, sign,
-                                     (0, 0), upper, &mut buf, &mut parts)
-    };
-    fmt.pad_formatted_parts(&formatted)
+        float_to_exponential_common_shortest(fmt, num, sign, upper)
+    }
 }
 
 macro_rules! floating {

src/libcore/mem.rs

@@ -40,7 +40,7 @@ pub use intrinsics::transmute;
 /// `forget` is not marked as `unsafe`, because Rust's safety guarantees
 /// do not include a guarantee that destructors will always run. For example,
 /// a program can create a reference cycle using [`Rc`][rc], or call
-/// [`process:exit`][exit] to exit without running destructors. Thus, allowing
+/// [`process::exit`][exit] to exit without running destructors. Thus, allowing
 /// `mem::forget` from safe code does not fundamentally change Rust's safety
 /// guarantees.
 ///

src/librustc/middle/dead.rs

@@ -283,6 +283,12 @@ fn has_allow_dead_code_or_lang_attr(attrs: &[ast::Attribute]) -> bool {
         return true;
     }
 
+    // #[used] also keeps the item alive forcefully,
+    // e.g. for placing it in a specific section.
+    if attr::contains_name(attrs, "used") {
+        return true;
+    }
+
     let dead_code = lint::builtin::DEAD_CODE.name_lower();
     for attr in lint::gather_attrs(attrs) {
         match attr {

src/test/run-pass/issue-41628.rs

@@ -0,0 +1,17 @@
+// Copyright 2017 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.
+
+#![deny(dead_code)]
+#![feature(used)]
+
+#[used]
+static FOO: u32 = 0;
+
+fn main() {}