Rollup of 21 pull requests

src/doc/reference.md

@@ -1636,6 +1636,10 @@ The type of a function declared in an extern block is `extern "abi" fn(A1, ...,
 An) -> R`, where `A1...An` are the declared types of its arguments and `R` is
 the declared return type.
 
+It is valid to add the `link` attribute on an empty extern block. You can use
+this to satisfy the linking requirements of extern blocks elsewhere in your code
+(including upstream crates) instead of adding the attribute to each extern block.
+
 ## Visibility and Privacy
 
 These two terms are often used interchangeably, and what they are attempting to

src/doc/trpl/SUMMARY.md

@@ -63,7 +63,7 @@
     * [No stdlib](no-stdlib.md)
     * [Intrinsics](intrinsics.md)
     * [Lang items](lang-items.md)
-    * [Link args](link-args.md)
+    * [Advanced linking](advanced-linking.md)
     * [Benchmark Tests](benchmark-tests.md)
     * [Box Syntax and Patterns](box-syntax-and-patterns.md)
     * [Slice Patterns](slice-patterns.md)

src/doc/trpl/advanced-linking.md

@@ -0,0 +1,151 @@
+% Advanced Linking
+
+The common cases of linking with Rust have been covered earlier in this book,
+but supporting the range of linking possibilities made available by other
+languages is important for Rust to achieve seamless interaction with native
+libraries.
+
+# Link args
+
+There is one other way to tell `rustc` how to customize linking, and that is via
+the `link_args` attribute. This attribute is applied to `extern` blocks and
+specifies raw flags which need to get passed to the linker when producing an
+artifact. An example usage would be:
+
+``` no_run
+#![feature(link_args)]
+
+#[link_args = "-foo -bar -baz"]
+extern {}
+# fn main() {}
+```
+
+Note that this feature is currently hidden behind the `feature(link_args)` gate
+because this is not a sanctioned way of performing linking. Right now `rustc`
+shells out to the system linker (`gcc` on most systems, `link.exe` on MSVC),
+so it makes sense to provide extra command line
+arguments, but this will not always be the case. In the future `rustc` may use
+LLVM directly to link native libraries, in which case `link_args` will have no
+meaning. You can achieve the same effect as the `link-args` attribute with the
+`-C link-args` argument to `rustc`.
+
+It is highly recommended to *not* use this attribute, and rather use the more
+formal `#[link(...)]` attribute on `extern` blocks instead.
+
+# Static linking
+
+Static linking refers to the process of creating output that contain all
+required libraries and so don't need libraries installed on every system where
+you want to use your compiled project. Pure-Rust dependencies are statically
+linked by default so you can use created binaries and libraries without
+installing the Rust everywhere. By contrast, native libraries
+(e.g. `libc` and `libm`) usually dynamically linked, but it is possible to
+change this and statically link them as well.
+
+Linking is a very platform dependent topic — on some platforms, static linking
+may not be possible at all! This section assumes some basic familiarity with
+linking on your platform of choice.
+
+## Linux
+
+By default, all Rust programs on Linux will link to the system `libc` along with
+a number of other libraries. Let's look at an example on a 64-bit Linux machine
+with GCC and `glibc` (by far the most common `libc` on Linux):
+
+``` text
+$ cat example.rs
+fn main() {}
+$ rustc example.rs
+$ ldd example
+        linux-vdso.so.1 =>  (0x00007ffd565fd000)
+        libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007fa81889c000)
+        libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007fa81867e000)
+        librt.so.1 => /lib/x86_64-linux-gnu/librt.so.1 (0x00007fa818475000)
+        libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007fa81825f000)
+        libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007fa817e9a000)
+        /lib64/ld-linux-x86-64.so.2 (0x00007fa818cf9000)
+        libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007fa817b93000)
+```
+
+Dynamic linking on Linux can be undesirable if you wish to use new library
+features on old systems or target systems which do not have the required
+dependencies for your program to run.
+
+Static linking is supported via an alternative `libc`, `musl` - this must be
+enabled at Rust compile-time with some prerequisites available. You can compile
+your own version of Rust with `musl` enabled and install it into a custom
+directory with the instructions below:
+
+```
+$ mkdir musldist
+$ PREFIX=$(pwd)/musldist
+$
+$ # Build musl
+$ wget http://www.musl-libc.org/releases/musl-1.1.10.tar.gz
+[...]
+$ tar xf musl-1.1.10.tar.gz
+$ cd musl-1.1.10/
+musl-1.1.10 $ ./configure --disable-shared --prefix=$PREFIX
+[...]
+musl-1.1.10 $ make
+[...]
+musl-1.1.10 $ make install
+[...]
+musl-1.1.10 $ cd ..
+$ du -h musldist/lib/libc.a
+2.2M    musldist/lib/libc.a
+$
+$ # Build libunwind.a
+$ wget http://llvm.org/releases/3.6.1/llvm-3.6.1.src.tar.xz
+$ tar xf llvm-3.6.1.src.tar.xz
+$ cd llvm-3.6.1.src/projects/
+llvm-3.6.1.src/projects $ svn co http://llvm.org/svn/llvm-project/libcxxabi/trunk/ libcxxabi
+llvm-3.6.1.src/projects $ svn co http://llvm.org/svn/llvm-project/libunwind/trunk/ libunwind
+llvm-3.6.1.src/projects $ sed -i 's#^\(include_directories\).*$#\0\n\1(../libcxxabi/include)#' libunwind/CMakeLists.txt
+llvm-3.6.1.src/projects $ mkdir libunwind/build
+llvm-3.6.1.src/projects $ cd libunwind/build
+llvm-3.6.1.src/projects/libunwind/build $ cmake -DLLVM_PATH=../../.. -DLIBUNWIND_ENABLE_SHARED=0 ..
+llvm-3.6.1.src/projects/libunwind/build $ make
+llvm-3.6.1.src/projects/libunwind/build $ cp lib/libunwind.a $PREFIX/lib/
+llvm-3.6.1.src/projects/libunwind/build $ cd cd ../../../../
+$ du -h musldist/lib/libunwind.a
+164K    musldist/lib/libunwind.a
+$
+$ # Build musl-enabled rust
+$ git clone https://github.com/rust-lang/rust.git muslrust
+$ cd muslrust
+muslrust $ ./configure --target=x86_64-unknown-linux-musl --musl-root=$PREFIX --prefix=$PREFIX
+muslrust $ make
+muslrust $ make install
+muslrust $ cd ..
+$ du -h musldist/bin/rustc
+12K     musldist/bin/rustc
+```
+
+You now have a build of a `musl`-enabled Rust! Because we've installed it to a
+custom prefix we need to make sure our system can the binaries and appropriate
+libraries when we try and run it:
+
+```
+$ export PATH=$PREFIX/bin:$PATH
+$ export LD_LIBRARY_PATH=$PREFIX/lib:$LD_LIBRARY_PATH
+```
+
+Let's try it out!
+
+```
+$ echo 'fn main() { println!("hi!"); panic!("failed"); }' > example.rs
+$ rustc --target=x86_64-unknown-linux-musl example.rs
+$ ldd example
+        not a dynamic executable
+$ ./example
+hi!
+thread '<main>' panicked at 'failed', example.rs:1
+```
+
+Success! This binary can be copied to almost any Linux machine with the same
+machine architecture and run without issues.
+
+`cargo build` also permits the `--target` option so you should be able to build
+your crates as normal. However, you may need to recompile your native libraries
+against `musl` before they can be linked against.

src/doc/trpl/ffi.md

@@ -340,7 +340,7 @@ libraries:
 Note that frameworks are only available on OSX targets.
 
 The different `kind` values are meant to differentiate how the native library
-participates in linkage. From a linkage perspective, the rust compiler creates
+participates in linkage. From a linkage perspective, the Rust compiler creates
 two flavors of artifacts: partial (rlib/staticlib) and final (dylib/binary).
 Native dynamic library and framework dependencies are propagated to the final
 artifact boundary, while static library dependencies are not propagated at
@@ -350,9 +350,9 @@ artifact.
 A few examples of how this model can be used are:
 
 * A native build dependency. Sometimes some C/C++ glue is needed when writing
-  some rust code, but distribution of the C/C++ code in a library format is just
+  some Rust code, but distribution of the C/C++ code in a library format is just
   a burden. In this case, the code will be archived into `libfoo.a` and then the
-  rust crate would declare a dependency via `#[link(name = "foo", kind =
+  Rust crate would declare a dependency via `#[link(name = "foo", kind =
   "static")]`.
 
   Regardless of the flavor of output for the crate, the native static library
@@ -361,7 +361,7 @@ A few examples of how this model can be used are:
 
 * A normal dynamic dependency. Common system libraries (like `readline`) are
   available on a large number of systems, and often a static copy of these
-  libraries cannot be found. When this dependency is included in a rust crate,
+  libraries cannot be found. When this dependency is included in a Rust crate,
   partial targets (like rlibs) will not link to the library, but when the rlib
   is included in a final target (like a binary), the native library will be
   linked in.

src/doc/trpl/release-channels.md

@@ -43,3 +43,26 @@ This will help alert the team in case there’s an accidental regression.
 Additionally, testing against nightly can catch regressions even sooner, and so
 if you don’t mind a third build, we’d appreciate testing against all channels.
 
+As an example, many Rust programmers use [Travis](https://travis-ci.org/) to
+test their crates, which is free for open source projects. Travis [supports
+Rust directly][travis], and you can use a `.travis.yml` file like this to
+test on all channels:
+
+```yaml
+language: rust
+rust:
+  - nightly
+  - beta
+  - stable
+
+matrix:
+  allow_failures:
+    - rust: nightly
+```
+
+[travis]: http://docs.travis-ci.com/user/languages/rust/
+
+With this configuration, Travis will test all three channels, but if something
+breaks on nightly, it won’t fail your build. A similar configuration is
+recommended for any CI system, check the documentation of the one you’re
+using for more details.

src/doc/trpl/unsafe.md

@@ -100,10 +100,14 @@ that you normally can not do. Just three. Here they are:
 
 That’s it. It’s important that `unsafe` does not, for example, ‘turn off the
 borrow checker’. Adding `unsafe` to some random Rust code doesn’t change its
-semantics, it won’t just start accepting anything.
+semantics, it won’t just start accepting anything. But it will let you write
+things that _do_ break some of the rules.
 
-But it will let you write things that _do_ break some of the rules. Let’s go
-over these three abilities in order.
+You will also encounter the `unsafe` keyword when writing bindings to foreign
+(non-Rust) interfaces. You're encouraged to write a safe, native Rust interface
+around the methods provided by the library.
+
+Let’s go over the basic three abilities listed, in order.
 
 ## Access or update a `static mut`
 

src/libcore/iter.rs

@@ -2555,7 +2555,7 @@ impl<I: RandomAccessIterator, F> RandomAccessIterator for Inspect<I, F>
 #[unstable(feature = "iter_unfold")]
 #[derive(Clone)]
 #[deprecated(since = "1.2.0",
-             reason = "has gained enough traction to retain its position \
+             reason = "has not gained enough traction to retain its position \
                        in the standard library")]
 #[allow(deprecated)]
 pub struct Unfold<St, F> {
@@ -2567,7 +2567,7 @@ pub struct Unfold<St, F> {
 
 #[unstable(feature = "iter_unfold")]
 #[deprecated(since = "1.2.0",
-             reason = "has gained enough traction to retain its position \
+             reason = "has not gained enough traction to retain its position \
                        in the standard library")]
 #[allow(deprecated)]
 impl<A, St, F> Unfold<St, F> where F: FnMut(&mut St) -> Option<A> {
@@ -3018,7 +3018,7 @@ type IterateState<T, F> = (F, Option<T>, bool);
 /// from a given seed value.
 #[unstable(feature = "iter_iterate")]
 #[deprecated(since = "1.2.0",
-             reason = "has gained enough traction to retain its position \
+             reason = "has not gained enough traction to retain its position \
                        in the standard library")]
 #[allow(deprecated)]
 pub type Iterate<T, F> = Unfold<IterateState<T, F>, fn(&mut IterateState<T, F>) -> Option<T>>;
@@ -3027,7 +3027,7 @@ pub type Iterate<T, F> = Unfold<IterateState<T, F>, fn(&mut IterateState<T, F>)
 /// repeated applications of the given function `f`.
 #[unstable(feature = "iter_iterate")]
 #[deprecated(since = "1.2.0",
-             reason = "has gained enough traction to retain its position \
+             reason = "has not gained enough traction to retain its position \
                        in the standard library")]
 #[allow(deprecated)]
 pub fn iterate<T, F>(seed: T, f: F) -> Iterate<T, F> where

src/librustc/middle/intrinsicck.rs

@@ -165,7 +165,7 @@ impl<'a, 'tcx> IntrinsicCheckingVisitor<'a, 'tcx> {
         if from_tc.interior_param() || to_tc.interior_param() {
             span_err!(self.tcx.sess, span, E0139,
                       "cannot transmute to or from a type that contains \
-                       type parameters in its interior");
+                       unsubstituted type parameters");
             return;
         }
 

src/librustc/middle/ty.rs

@@ -44,7 +44,7 @@ use metadata::csearch;
 use middle;
 use middle::cast;
 use middle::check_const;
-use middle::const_eval::{self, ConstVal};
+use middle::const_eval::{self, ConstVal, ErrKind};
 use middle::def::{self, DefMap, ExportMap};
 use middle::dependency_format;
 use middle::fast_reject;
@@ -6098,20 +6098,20 @@ impl<'tcx> ctxt<'tcx> {
                     found);
             }
             Err(err) => {
-                let err_description = err.description();
-                let found = match count_expr.node {
+                let err_msg = match count_expr.node {
                     ast::ExprPath(None, ast::Path {
                         global: false,
                         ref segments,
                         ..
                     }) if segments.len() == 1 =>
-                        format!("{}", "found variable"),
-                    _ =>
-                        format!("but {}", err_description),
+                        format!("found variable"),
+                    _ => match err.kind {
+                        ErrKind::MiscCatchAll => format!("but found {}", err.description()),
+                        _ => format!("but {}", err.description())
+                    }
                 };
                 span_err!(self.sess, count_expr.span, E0307,
-                    "expected constant integer for repeat count, {}",
-                    found);
+                    "expected constant integer for repeat count, {}", err_msg);
             }
         }
         0