---

yaml
---
r: 233595
b: refs/heads/beta
c: 5e5b99f
h: refs/heads/master
i:
  233593: 68ae4da
  233591: d3f31fe
v: v3

Author: bors

[refs]

@@ -23,7 +23,7 @@ refs/tags/0.9: 36870b185fc5f5486636d4515f0e22677493f225
 refs/tags/0.10: ac33f2b15782272ae348dbd7b14b8257b2148b5a
 refs/tags/0.11.0: e1247cb1d0d681be034adb4b558b5a0c0d5720f9
 refs/tags/0.12.0: f0c419429ef30723ceaf6b42f9b5a2aeb5d2e2d1
-refs/heads/beta: 81eab1cab6e96b4430409245b83cc51cd40c2f9f
+refs/heads/beta: 5e5b99f47f4d96d2e3fabd05dc5a128a41245187
 refs/tags/1.0.0-alpha: e42bd6d93a1d3433c486200587f8f9e12590a4d7
 refs/heads/tmp: 370fe2786109360f7c35b8ba552b83b773dd71d6
 refs/tags/1.0.0-alpha.2: 4c705f6bc559886632d3871b04f58aab093bfa2f

branches/beta/README.md

@@ -82,6 +82,28 @@ Read ["Installing Rust"] from [The Book].
    $ make && make install
    ```
 
+## Building Documentation
+
+If you’d like to build the documentation, it’s almost the same:
+
+```sh
+./configure
+$ make docs
+```
+
+Building the documentation requires building the compiler, so the above
+details will apply. Once you have the compiler built, you can
+
+```sh
+$ make docs NO_REBUILD=1 
+```
+
+To make sure you don’t re-build the compiler because you made a change
+to some documentation.
+
+The generated documentation will appear in a top-level `doc` directory,
+created by the `make` rule.
+
 ## Notes
 
 Since the Rust compiler is written in Rust, it must be built by a

branches/beta/configure

@@ -607,6 +607,10 @@ valopt aarch64-linux-android-ndk "" "aarch64-linux-android NDK standalone path"
 valopt release-channel "dev" "the name of the release channel to build"
 valopt musl-root "/usr/local" "MUSL root installation directory"
 
+# Used on systems where "cc" and "ar" are unavailable
+valopt default-linker "cc" "the default linker"
+valopt default-ar     "ar" "the default ar"
+
 # Many of these are saved below during the "writing configuration" step
 # (others are conditionally saved).
 opt_nosave manage-submodules 1 "let the build manage the git submodules"

branches/beta/man/rustc.1

@@ -41,7 +41,7 @@ look for anything here (the default)
 .RE
 .TP
 \fB\-l\fR [\fIKIND\fR=]\fINAME\fR
-Link the generated crate(s) to the specified native library \fINAME\fR.
+Link the generated crate(s) to the specified library \fINAME\fR.
 The optional \fIKIND\fR can be one of \fIstatic\fR, \fIdylib\fR, or
 \fIframework\fR.
 If omitted, \fIdylib\fR is assumed.
@@ -113,7 +113,8 @@ Print version info and exit.
 Use verbose output.
 .TP
 \fB\-\-extern\fR \fINAME\fR=\fIPATH\fR
-Specify where an external rust library is located.
+Specify where an external rust library is located. These should match
+\fIextern\fR declarations in the crate's source code.
 .TP
 \fB\-\-sysroot\fR \fIPATH\fR
 Override the system root.

branches/beta/mk/target.mk

@@ -13,6 +13,10 @@
 # this exists can be found on issue #2400
 export CFG_COMPILER_HOST_TRIPLE
 
+# Used as defaults for the runtime ar and cc tools
+export CFG_DEFAULT_LINKER
+export CFG_DEFAULT_AR
+
 # The standard libraries should be held up to a higher standard than any old
 # code, make sure that these common warnings are denied by default. These can
 # be overridden during development temporarily. For stage0, we allow warnings

branches/beta/src/doc/reference.md

@@ -2059,6 +2059,11 @@ The following configurations must be defined by the implementation:
   `"mips"`, `"powerpc"`, `"arm"`, or `"aarch64"`.
 * `target_endian = "..."`. Endianness of the target CPU, either `"little"` or
   `"big"`.
+* `target_env = ".."` - an option provided by the compiler by default
+  describing the runtime environment of the target platform. Some examples of
+  this are `musl` for builds targeting the MUSL libc implementation, `msvc` for
+  Windows builds targeting MSVC, and `gnu` frequently the rest of the time. This
+  option may also be blank on some platforms.
 * `target_family = "..."`. Operating system family of the target, e. g.
   `"unix"` or `"windows"`. The value of this configuration option is defined
   as a configuration itself, like `unix` or `windows`.

branches/beta/src/doc/trpl/functions.md

@@ -214,11 +214,61 @@ fn diverges() -> ! {
 
 `panic!` is a macro, similar to `println!()` that we’ve already seen. Unlike
 `println!()`, `panic!()` causes the current thread of execution to crash with
-the given message.
+the given message. Because this function will cause a crash, it will never
+return, and so it has the type ‘`!`’, which is read ‘diverges’.
 
-Because this function will cause a crash, it will never return, and so it has
-the type ‘`!`’, which is read ‘diverges’. A diverging function can be used
-as any type:
+If you add a main function that calls `diverges()` and run it, you’ll get
+some output that looks like this:
+
+```text
+thread ‘<main>’ panicked at ‘This function never returns!’, hello.rs:2
+```
+
+If you want more information, you can get a backtrace by setting the
+`RUST_BACKTRACE` environment variable:
+
+```text
+$ RUST_BACKTRACE=1 ./diverges
+thread '<main>' panicked at 'This function never returns!', hello.rs:2
+stack backtrace:
+   1:     0x7f402773a829 - sys::backtrace::write::h0942de78b6c02817K8r
+   2:     0x7f402773d7fc - panicking::on_panic::h3f23f9d0b5f4c91bu9w
+   3:     0x7f402773960e - rt::unwind::begin_unwind_inner::h2844b8c5e81e79558Bw
+   4:     0x7f4027738893 - rt::unwind::begin_unwind::h4375279447423903650
+   5:     0x7f4027738809 - diverges::h2266b4c4b850236beaa
+   6:     0x7f40277389e5 - main::h19bb1149c2f00ecfBaa
+   7:     0x7f402773f514 - rt::unwind::try::try_fn::h13186883479104382231
+   8:     0x7f402773d1d8 - __rust_try
+   9:     0x7f402773f201 - rt::lang_start::ha172a3ce74bb453aK5w
+  10:     0x7f4027738a19 - main
+  11:     0x7f402694ab44 - __libc_start_main
+  12:     0x7f40277386c8 - <unknown>
+  13:                0x0 - <unknown>
+```
+
+`RUST_BACKTRACE` also works with Cargo’s `run` command:
+
+```text
+$ RUST_BACKTRACE=1 cargo run
+     Running `target/debug/diverges`
+thread '<main>' panicked at 'This function never returns!', hello.rs:2
+stack backtrace:
+   1:     0x7f402773a829 - sys::backtrace::write::h0942de78b6c02817K8r
+   2:     0x7f402773d7fc - panicking::on_panic::h3f23f9d0b5f4c91bu9w
+   3:     0x7f402773960e - rt::unwind::begin_unwind_inner::h2844b8c5e81e79558Bw
+   4:     0x7f4027738893 - rt::unwind::begin_unwind::h4375279447423903650
+   5:     0x7f4027738809 - diverges::h2266b4c4b850236beaa
+   6:     0x7f40277389e5 - main::h19bb1149c2f00ecfBaa
+   7:     0x7f402773f514 - rt::unwind::try::try_fn::h13186883479104382231
+   8:     0x7f402773d1d8 - __rust_try
+   9:     0x7f402773f201 - rt::lang_start::ha172a3ce74bb453aK5w
+  10:     0x7f4027738a19 - main
+  11:     0x7f402694ab44 - __libc_start_main
+  12:     0x7f40277386c8 - <unknown>
+  13:                0x0 - <unknown>
+```
+
+A diverging function can be used as any type:
 
 ```should_panic
 # fn diverges() -> ! {