The current behaviour of dumping in the current directory is rarely
desirable: a sensible default directory for dumping is much more
convenient.

When we suggest the replacement for a macro we include the "!" in the
suggested replacement but the span only contains the name of the macro
itself. Using that replacement would cause a duplicate "!" in the
resulting code.

I originally tried to extend the span to be replaced by 1 byte in
rust-lang#47424. However, @zackmdavis pointed out that there can be
whitespace between the macro name and the bang.

Instead, just remove the bang from the suggested replacement.

Fixes rust-lang#47418

Closes rust-lang#45045

These are already removed in the normal optimization pipeline - so this
should slightly improve codegen performance, as these cleanup blocks are
known to hurt LLVM.

This un-regresses and is therefore a fix for rust-lang#47442. However, the
reporter of that issue should try using `-C panic=abort` instead of
carefully avoiding panics.

Avoid overlapping spans by only pointing at the arguments that are not
being used in the argument string. Enable libsyntax to have diagnostics
with multiple primary spans by accepting `Into<MultiSpan>` instead of
`Span`.

The incompetent fool who added these suggestions in 38e5a96 apparently
thought it was safe to assume that, because the offending function or
static was unreachable, it would therefore have not have any existing
visibility modifiers, making it safe for us to unconditionally suggest
inserting `pub`. This isn't true.

This resolves rust-lang#47383.

This patch implements "only-<platforms>" for tests headers using which one can
specify just the platforms on which the test should run rather than listing all
the platforms to ignore using "ignore-<platforms>".

This is a fix for issues rust-lang#33581 and rust-lang#47459.

Previous patch introduced something like if x {true} else {false} which can be
simply replaced by returning x here.

Thanks to @kennytm for spotting it.

The function parse_cfg_prefix() is not really parsing. It's just checking
whether the prefix is present or not. So the new function name as suggested by
@Mark-Simulacrum is better.

Setting up a cross compilation toolchain for CloudABI is relatively
easy. It's just a matter of installing a somewhat recent version of
Clang (5.0 preferred) and installing the corresponding
${target}-cxx-runtime package, containing a set of core C/C++ libraries
(libc, libc++, libunwind, etc).

Eventually it would be nice if we could also run 'x.py test'. That,
however still requires some more work. Both libtest and compiletest
would need to be adjusted to deal with CloudABI's requirement of having
all of an application's dependencies injected. Let's settle for just
doing 'x.py dist' for now.

There is not enough capacity to do automated builds for CloudABI at this
time.

`map_or` and `map_or_else` don't use `Default::default`, but `unwrap_or_default` does.

No longer uses a magic string for missing or root module.

As discussed in rust-lang#47427, let's not have a separate container for doing
CloudABI builds. It's a lot faster if we integrate it into an existing
container, so there's less duplication of what's being built.

Upgrade the existing container to Ubuntu 17.10, which is required for
CloudABI builds. The version of Clang shipped with 16.04 is not recent
enough to support CloudABI properly.

We'll turn on other architectures if it turns out we have enough
capacity.

This fixes an accidental regression rust-lang#46335 where the behavior of
`Path::ends_with` is different from `str::ends_with` (paths operate over
components, strs operate over chars).

Pull in rust-lang/rust-installer#76 to get streamed tarball generation,
rather than batching it all in memory, while still getting the benefit
of compressing in parallel.

…ster

fix faulty comment

after rust-lang#43506 there is no fixed number of request sent.

…k, r=dtolnay

Optimize slice.{r}position result bounds check

Second attempt of rust-lang#45501
Fixes rust-lang#45964

Demo: https://godbolt.org/g/N4mBHp

…teveklabnik

Report errors instead of panic!() when linkcheck encounters absolute paths

The RBE contained some absolute links that failed the link check in rust-lang#46196. Diagnosing these issues was needlessly complicated, thanks to the linkchecker just panicing instead of reporting proper errors.

This PR replaces the panic with a proper `*errors = true` + error message handling.

The linkchecker itself doesn't have any tests so I intentionally didn't touch anything else than the code that previously did the `panic!()`. A small code quality improvement might be made by binding the `Path::new(base).join(url)` into a variable before the for-loop and using this resolved url in both the for loop and the error message.

r? @steveklabnik

(If not for any other reason than having r on the rust-lang#46196.)

… r=steveklabnik

Standardize on "re-export" rather than "reexport"

While working on the book with our editors, it was brought to our attention that we're not consistent with when we use "re-export" versus "reexport". For the book, we've decided (with our editors) to go with "re-export"; in prose, I think that looks better. In code, I'm fine with "reexport".

However, the rustdoc generated section is currently "Reexports", so when we have a screenshot of generated documentation with the prose where we use "re-export", it's inconsistent.

It's too late to fix this for the book because we're using 1.21.0 for the output in the book, and it's really only one spot so it's not a huge deal, but I'd like to advocate for changing the documentation header so that a future edition of the book can be consistent.

The first commit here only changes the documentation section heading text and rustdoc documentation that references it. This is the commit that's most important to me.

The second commit changes error messages and associated tests to also be consistent with the use of re-export. This is the next most important commit to me, but I could be argued out of this one because then it won't match code like the `macro_reexports` feature name, which ostensibly should change to `macro_re_exports` to be most consistent but I didn't want to change code.

The last commit changes re-export anywhere else in prose: either in documentation comments or regular comments. This is least important as most of them aren't user-visible. Instances like these will likely sneak back in over time. I'm totally fine dropping this commit if anyone wants, but [the hobgoblins made me do it](http://www.bartleby.com/100/420.47.html) and it sets a good example.

r? @steveklabnik

fix mispositioned span

This fixes rust-lang#47377

The output now looks like this
```
error[E0369]: binary operation `+` cannot be applied to type `&str`
 --> h.rs:3:11
  |
3 |     let _a = b + ", World!";
  |              ^^^^^^^^^^^^^^ `+` can't be used to concatenate two `&str` strings
help: `to_owned()` can be used to create an owned `String` from a string reference. String concatenation appends the string on the right to the string on the left and may require reallocation. This requires ownership of the string on the left
  |
3 |     let _a = b.to_owned() + ", World!";
  |              ^^^^^^^^^

error: aborting due to previous error
```
For the case when emojis are involved,  it gives the new output for proper indentation.
But for an indentation as follows,
```
fn main() {
let b = "hello";
    let _a = b + ", World!";
}
```
it still mispositions the span
```
3 |     println!("🦀🦀🦀🦀🦀"); let _a = b + ", World!";
  |                                           ^^^^^^^^^^^^^^ `+` can't be used to concatenate two `&str` strings
  |
3 |     println!("🦀🦀🦀🦀🦀"); let _a = b.to_owned() + ", World!";
  |                                           ^^^^^^^
error: aborting due to previous erro
```

cc @estebank  @est31

…matsakis

Add a default directory for -Zmir-dump-dir

The current behaviour of dumping in the current directory is rarely
desirable: a sensible default directory for dumping is much more
convenient. This makes sets the default value for `-Zmir-dump-dir`
to `mir_dump/`.

r? @eddyb

Add a Docker container for doing automated builds for CloudABI.

Setting up a cross compilation toolchain for CloudABI is relatively
easy. It's just a matter of installing a somewhat recent version of
Clang (5.0 preferred) and installing the corresponding
`${target}-cxx-runtime` package, containing a set of core C/C++ libraries
(libc, libc++, libunwind, etc).

Eventually it would be nice if we could also run `x.py test`. That,
however still requires some more work. Both libtest and compiletest
would need to be adjusted to deal with CloudABI's requirement of having
all of an application's dependencies injected. Let's settle for just
doing `x.py dist` for now.

…tMisdreavus

Update html-diff crate => fix unicode parsing and invalid paths

r? @QuietMisdreavus

…suggestion, r=estebank

Don't include bang in macro replacement suggestion

When we suggest the replacement for a macro we include the "!" in the suggested replacement but the span only contains the name of the macro itself. Using that replacement would cause a duplicate "!" in the resulting code.

I originally tried to extend the span to be replaced by 1 byte in rust-lang#47424. However, @zackmdavis pointed out that there can be whitespace between the macro name and the bang.

Instead, just remove the bang from the suggested replacement.

Fixes rust-lang#47418

r? @estebank

Add NLL test for rust-lang#45045

cc rust-lang#45045
Part of rust-lang#47366

r? @nikomatsakis

Allow a trailing comma in lint_array

fix rust-lang#47428

remove noop landing pads in cleanup shims

No-op landing pads are already removed in the normal optimization pipeline - so also removing them on the shim pipeline should slightly improve codegen performance, as these cleanup blocks are known to hurt LLVM.

This un-regresses and is therefore a fix for rust-lang#47442. However, the reporter of that issue should try using `-C panic=abort` instead of carefully avoiding panics.

r? @eddyb

…ested_double-pub, r=estebank

private no-mangle lints: only suggest `pub` if it doesn't already exist

Fixes rust-lang#47383 (function or static can be `pub` but unreachable because it's in a private module; adding another `pub` is nonsensical).

r? @estebank

Point at unused arguments for format string

Avoid overlapping spans by only pointing at the arguments that are not
being used in the argument string. Enable libsyntax to have diagnostics
with multiple primary spans by accepting `Into<MultiSpan>` instead of
`Span`.

Partially addresses rust-lang#41850.

…excrichton

Add "-lmsvcrt" twice to get rustc to build with the latest mingw64

After updating mingw-w64 in Msys2, I started getting this when doing `./x.py build --stage 1 src/libtest`:
```
error: linking with `gcc` failed: exit code: 1
  |
  = note: "gcc" "-Wl,--enable-long-section-names" "-fno-use-linker-plugin" "-Wl,--nxcompat" "-nostdlib" "-m64" "rust\\msys64\\home\\...\\rust\\build\\x86_64-pc-windows-gnu\\stage0-sysroot\\lib\\rustlib\\x86_64-pc-windows-gnu\\lib\\crt2.o" "rust\\msys64\\home\\...\\rust\\build\\x86_64-pc-windows-gnu\\stage0-sysroot\\lib\\rustlib\\x86_64-pc-windows-gnu\\lib\\rsbegin.o" "-L" "rust\\msys64\\home\\...\\rust\\build\\x86_64-pc-windows-gnu\\stage0-sysroot\\lib\\rustlib\\x86_64-pc-windows-gnu\\lib" "rust\\msys64\\home\\...\\rust\\build\\x86_64-pc-windows-gnu\\stage0-rustc\\x86_64-pc-windows-gnu\\release\\deps\\rustc-b67a4fe646fd8794.rustc0-833528dbd46ff06c3b1f5154abdef2ed.rs.rcgu.o" "rust\\msys64\\home\\...\\rust\\build\\x86_64-pc-windows-gnu\\stage0-rustc\\x86_64-pc-windows-gnu\\release\\deps\\rustc-b67a4fe646fd8794.rustc1-833528dbd46ff06c3b1f5154abdef2ed.rs.rcgu.o" "-o" "rust\\msys64\\home\\...\\rust\\build\\x86_64-pc-windows-gnu\\stage0-rustc\\x86_64-pc-windows-gnu\\release\\deps\\rustc-b67a4fe646fd8794.exe" "rust\\msys64\\home\\...\\rust\\build\\x86_64-pc-windows-gnu\\stage0-rustc\\x86_64-pc-windows-gnu\\release\\deps\\rustc-b67a4fe646fd8794.crate.allocator.rcgu.o" "-Wl,--gc-sections" "-nodefaultlibs" "-L" "rust\\msys64\\home\\...\\rust\\build\\x86_64-pc-windows-gnu\\stage0-rustc\\x86_64-pc-windows-gnu\\release\\deps" "-L" "rust\\msys64\\home\\...\\rust\\build\\x86_64-pc-windows-gnu\\stage0-rustc\\release\\deps" "-L" "...\\.cargo\\registry\\src\\github.com-1ecc6299db9ec823\\dbghelp-sys-0.2.0/x86_64" "-L" "rust\\msys64\\home\\...\\rust\\build\\x86_64-pc-windows-gnu\\stage0-rustc\\x86_64-pc-windows-gnu\\release\\build\\miniz-sys-98d83a845f69b3ab\\out" "-L" "rust\\msys64\\home\\...\\rust\\build\\x86_64-pc-windows-gnu\\stage0-rustc\\x86_64-pc-windows-gnu\\release\\build\\rustc_binaryen-f106436b515711ff\\out/build/lib" "-L" "rust\\msys64\\home\\...\\rust\\build\\x86_64-pc-windows-gnu\\stage0-rustc\\x86_64-pc-windows-gnu\\release\\build\\rustc_binaryen-f106436b515711ff\\out" "-L" "rust\\msys64\\home\\...\\rust\\build\\x86_64-pc-windows-gnu\\stage0-rustc\\x86_64-pc-windows-gnu\\release\\build\\rustc_llvm-9a040fa1f1937a67\\out" "-L" "rust\\msys64\\home\\...\\rust\\build\\x86_64-pc-windows-gnu\\llvm/lib" "-L" "rust\\msys64\\home\\...\\rust\\build\\x86_64-pc-windows-gnu\\stage0-sysroot\\lib\\rustlib\\x86_64-pc-windows-gnu\\lib" "-L" "rust\\msys64\\home\\...\\rust\\build\\x86_64-pc-windows-gnu\\stage0-rustc\\x86_64-pc-windows-gnu\\release\\deps" "-l" "rustc_driver-224d9efe142c632e" "-L" "rust\\msys64\\home\\...\\rust\\build\\x86_64-pc-windows-gnu\\stage0-rustc\\x86_64-pc-windows-gnu\\release\\deps" "-l" "rustc_trans-767a58ff60ff6a03" "-L" "rust\\msys64\\home\\...\\rust\\build\\x86_64-pc-windows-gnu\\stage0-rustc\\x86_64-pc-windows-gnu\\release\\deps" "-l" "rustc_resolve-bcc2d91b756552d1" "-L" "rust\\msys64\\home\\...\\rust\\build\\x86_64-pc-windows-gnu\\stage0-rustc\\x86_64-pc-windows-gnu\\release\\deps" "-l" "rustc_incremental-e93e816231352cc9" "-L" "rust\\msys64\\home\\...\\rust\\build\\x86_64-pc-windows-gnu\\stage0-rustc\\x86_64-pc-windows-gnu\\release\\deps" "-l" "rustc_plugin-8273bd6d564e8657" "-L" "rust\\msys64\\home\\...\\rust\\build\\x86_64-pc-windows-gnu\\stage0-rustc\\x86_64-pc-windows-gnu\\release\\deps" "-l" "rustc_metadata-5537b9a8ab6e6015" "-L" "rust\\msys64\\home\\...\\rust\\build\\x86_64-pc-windows-gnu\\stage0-rustc\\x86_64-pc-windows-gnu\\release\\deps" "-l" "rustc_lint-796681662b9ad8e1" "-L" "rust\\msys64\\home\\...\\rust\\build\\x86_64-pc-windows-gnu\\stage0-rustc\\x86_64-pc-windows-gnu\\release\\deps" "-l" "rustc_passes-9ef6de765e132a7c" "-L" "rust\\msys64\\home\\...\\rust\\build\\x86_64-pc-windows-gnu\\stage0-rustc\\x86_64-pc-windows-gnu\\release\\deps" "-l" "rustc_privacy-2289da126d06c49e" "-L" "rust\\msys64\\home\\...\\rust\\build\\x86_64-pc-windows-gnu\\stage0-rustc\\x86_64-pc-windows-gnu\\release\\deps" "-l" "rustc_llvm-893cdac51017c26f" "-L" "rust\\msys64\\home\\...\\rust\\build\\x86_64-pc-windows-gnu\\stage0-rustc\\x86_64-pc-windows-gnu\\release\\deps" "-l" "rustc_borrowck-ac2009fc1ce58d88" "-L" "rust\\msys64\\home\\...\\rust\\build\\x86_64-pc-windows-gnu\\stage0-rustc\\x86_64-pc-windows-gnu\\release\\deps" "-l" "rustc_mir-d4ce85a1cded4423" "-L" "rust\\msys64\\home\\...\\rust\\build\\x86_64-pc-windows-gnu\\stage0-rustc\\x86_64-pc-windows-gnu\\release\\deps" "-l" "rustc_const_eval-a4e766ec47afde96" "-L" "rust\\msys64\\home\\...\\rust\\build\\x86_64-pc-windows-gnu\\stage0-rustc\\x86_64-pc-windows-gnu\\release\\deps" "-l" "rustc_save_analysis-66d4c41e75392976" "-L" "rust\\msys64\\home\\...\\rust\\build\\x86_64-pc-windows-gnu\\stage0-rustc\\x86_64-pc-windows-gnu\\release\\deps" "-l" "rustc_typeck-4e21db5573af1446" "-L" "rust\\msys64\\home\\...\\rust\\build\\x86_64-pc-windows-gnu\\stage0-rustc\\x86_64-pc-windows-gnu\\release\\deps" "-l" "rustc_platform_intrinsics-f40c4b99b60d15e9" "-L" "rust\\msys64\\home\\...\\rust\\build\\x86_64-pc-windows-gnu\\stage0-rustc\\x86_64-pc-windows-gnu\\release\\deps" "-l" "rustc_allocator-86ef12c8efbcf068" "-L" "rust\\msys64\\home\\...\\rust\\build\\x86_64-pc-windows-gnu\\stage0-rustc\\x86_64-pc-windows-gnu\\release\\deps" "-l" "rustc_trans_utils-8199c3d0e673bb7b" "-L" "rust\\msys64\\home\\...\\rust\\build\\x86_64-pc-windows-gnu\\stage0-rustc\\x86_64-pc-windows-gnu\\release\\deps" "-l" "rustc-8f435ca07f1a04ff" "-L" "rust\\msys64\\home\\...\\rust\\build\\x86_64-pc-windows-gnu\\stage0-sysroot\\lib\\rustlib\\x86_64-pc-windows-gnu\\lib" "-l" "test-8abb197945b79a6a" "-L" "rust\\msys64\\home\\...\\rust\\build\\x86_64-pc-windows-gnu\\stage0-rustc\\x86_64-pc-windows-gnu\\release\\deps" "-l" "rustc_const_math-fa724350247d1ae6" "-L" "rust\\msys64\\home\\...\\rust\\build\\x86_64-pc-windows-gnu\\stage0-rustc\\x86_64-pc-windows-gnu\\release\\deps" "-l" "rustc_back-838b735c189dd798" "-L" "rust\\msys64\\home\\...\\rust\\build\\x86_64-pc-windows-gnu\\stage0-rustc\\x86_64-pc-windows-gnu\\release\\deps" "-l" "graphviz-42c69c0ff2aacc5b" "-L" "rust\\msys64\\home\\...\\rust\\build\\x86_64-pc-windows-gnu\\stage0-rustc\\x86_64-pc-windows-gnu\\release\\deps" "-l" "arena-454325a3f2773bc8" "-L" "rust\\msys64\\home\\...\\rust\\build\\x86_64-pc-windows-gnu\\stage0-rustc\\x86_64-pc-windows-gnu\\release\\deps" "-l" "syntax_ext-7880c41067f1be05" "-L" "rust\\msys64\\home\\...\\rust\\build\\x86_64-pc-windows-gnu\\stage0-rustc\\x86_64-pc-windows-gnu\\release\\deps" "-l" "proc_macro-f609718c6b927026" "-L" "rust\\msys64\\home\\...\\rust\\build\\x86_64-pc-windows-gnu\\stage0-rustc\\x86_64-pc-windows-gnu\\release\\deps" "-l" "syntax-3d2aaf6e201abcfe" "-L" "rust\\msys64\\home\\...\\rust\\build\\x86_64-pc-windows-gnu\\stage0-rustc\\x86_64-pc-windows-gnu\\release\\deps" "-l" "rustc_errors-2c007ffe6a847ed7" "-L" "rust\\msys64\\home\\...\\rust\\build\\x86_64-pc-windows-gnu\\stage0-rustc\\x86_64-pc-windows-gnu\\release\\deps" "-l" "syntax_pos-067e758dda669d03" "-L" "rust\\msys64\\home\\...\\rust\\build\\x86_64-pc-windows-gnu\\stage0-rustc\\x86_64-pc-windows-gnu\\release\\deps" "-l" "rustc_data_structures-50e5e6db2f34c196" "-L" "rust\\msys64\\home\\...\\rust\\build\\x86_64-pc-windows-gnu\\stage0-sysroot\\lib\\rustlib\\x86_64-pc-windows-gnu\\lib" "-l" "term-9d9f4c10ffba6dd6" "-L" "rust\\msys64\\home\\...\\rust\\build\\x86_64-pc-windows-gnu\\stage0-rustc\\x86_64-pc-windows-gnu\\release\\deps" "-l" "serialize-e55b4fb27a4d08bf" "-L" "rust\\msys64\\home\\...\\rust\\build\\x86_64-pc-windows-gnu\\stage0-rustc\\x86_64-pc-windows-gnu\\release\\deps" "-l" "rustc_cratesio_shim-baed94e463835a87" "-L" "rust\\msys64\\home\\...\\rust\\build\\x86_64-pc-windows-gnu\\stage0-rustc\\x86_64-pc-windows-gnu\\release\\deps" "-l" "fmt_macros-3c2cdca7d2f8dd09" "-L" "rust\\msys64\\home\\...\\rust\\build\\x86_64-pc-windows-gnu\\stage0-sysroot\\lib\\rustlib\\x86_64-pc-windows-gnu\\lib" "-l" "std-b1b09a5d7798628b" "-Wl,-Bstatic" "rust\\msys64\\home\\...\\rust\\build\\x86_64-pc-windows-gnu\\stage0-sysroot\\lib\\rustlib\\x86_64-pc-windows-gnu\\lib\\libcompiler_builtins-69f85297d9318c97.rlib" "-Wl,-Bdynamic" "-l" "advapi32" "-l" "ole32" "-l" "oleaut32" "-l" "psapi" "-l" "shell32" "-l" "ole32" "-l" "uuid" "-l" "stdc++" "-l" "gcc_eh" "-l" "pthread" "-l" "psapi" "-l" "dbghelp" "-l" "kernel32" "-l" "advapi32" "-l" "kernel32" "-l" "advapi32" "-l" "ws2_32" "-l" "userenv" "-l" "shell32" "-lmingwex" "-lmingw32" "-lgcc" "-lmsvcrt" "-luser32" "-lkernel32" "rust\\msys64\\home\\...\\rust\\build\\x86_64-pc-windows-gnu\\stage0-sysroot\\lib\\rustlib\\x86_64-pc-windows-gnu\\lib\\rsend.o"
  = note: rust/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/7.2.0/../../../../x86_64-w64-mingw32/lib/../lib/libmsvcrt.a(lib64_libmsvcrt_os_a-__p__fmode.o):__p__fmode.c:(.rdata$.refptr.__imp__fmode[.refptr.__imp__fmode]+0x0): undefined reference to `__imp__fmode'
          collect2.exe: error: ld returned 1 exit status

error: aborting due to previous error

error: Could not compile `rustc-main`.

Caused by:
  process didn't exit successfully: `rust\msys64\home\...\rust\build\bootstrap/debug/rustc --crate-name rustc rustc\rustc.rs --error-format json --crate-type bin --emit=dep-info,link -C opt-level=2 --cfg feature="jemalloc" --cfg feature="llvm" --cfg feature="rustc_back" --cfg feature="rustc_driver" -C metadata=b67a4fe646fd8794 -C extra-filename=-b67a4fe646fd8794 --out-dir rust\msys64\home\...\rust\build\x86_64-pc-windows-gnu\stage0-rustc\x86_64-pc-windows-gnu\release\deps --target x86_64-pc-windows-gnu -L dependency=rust\msys64\home\...\rust\build\x86_64-pc-windows-gnu\stage0-rustc\x86_64-pc-windows-gnu\release\deps -L dependency=rust\msys64\home\...\rust\build\x86_64-pc-windows-gnu\stage0-rustc\release\deps --extern rustc_back=rust\msys64\home\...\rust\build\x86_64-pc-windows-gnu\stage0-rustc\x86_64-pc-windows-gnu\release\deps\rustc_back-838b735c189dd798.dll --extern rustc_driver=rust\msys64\home\...\rust\build\x86_64-pc-windows-gnu\stage0-rustc\x86_64-pc-windows-gnu\release\deps\rustc_driver-224d9efe142c632e.dll -L native=...\.cargo\registry\src\github.com-1ecc6299db9ec823\dbghelp-sys-0.2.0/x86_64 -L native=rust\msys64\home\...\rust\build\x86_64-pc-windows-gnu\stage0-rustc\x86_64-pc-windows-gnu\release\build\miniz-sys-98d83a845f69b3ab\out -L native=rust\msys64\home\...\rust\build\x86_64-pc-windows-gnu\stage0-rustc\x86_64-pc-windows-gnu\release\build\rustc_binaryen-f106436b515711ff\out/build/lib -L native=rust\msys64\home\...\rust\build\x86_64-pc-windows-gnu\stage0-rustc\x86_64-pc-windows-gnu\release\build\rustc_binaryen-f106436b515711ff\out -L native=rust\msys64\home\...\rust\build\x86_64-pc-windows-gnu\stage0-rustc\x86_64-pc-windows-gnu\release\build\rustc_llvm-9a040fa1f1937a67\out -L native=rust\msys64\home\...\rust\build\x86_64-pc-windows-gnu\llvm/lib` (exit code: 101)
thread 'main' panicked at 'command did not execute successfully: "rust\\msys64\\home\\...\\rust\\build\\x86_64-pc-windows-gnu\\stage0/bin\\cargo.exe" "build" "--target" "x86_64-pc-windows-gnu" "-j" "4" "--release" "--features" " jemalloc llvm" "--manifest-path" "rust/msys64/home/.../rust\\src/rustc/Cargo.toml" "--message-format" "json"
expected success, got: exit code: 101', bootstrap\compile.rs:886:9
note: Run with `RUST_BACKTRACE=1` for a backtrace.
failed to run: rust/msys64/home/.../rust/build/bootstrap/debug/bootstrap build --stage 1 src/libtest
Build completed unsuccessfully in 0:00:25
```

The code that uses `__p__fmode` was added in mirror/mingw-w64@2e64b9e, apparently in x86_64, it uses its own implementation of it. libmsvcrt.a is kind of a weird beast, it's both an import library for the system msvcrt.dll, but it also is a library that includes compiled code.

For some reason it fails to find the reference for the import symbol that is found in the very same archive as the function that uses it. I don't know what in the Rust code base triggers this. i.e. Create an MWE that can show why this PR is required.

This probably *shouldn't be merged* without understanding why this is necessary or not.

To successfully bootstrap rustc and show that this does make the build work (On latest mingw-w64 x86_64 on Msys2):
```sh
$ RUSTFLAGS="-C link-arg=-lmsvcrt" ./x.py build --stage 1 src/libtest
$ ./x.py build --keep-stage 1 --stage 2 src/libtest # Should work with the patch, and fail without it
```

Issue rust-lang#47265

implement "only-<platforms>" for test headers

This patch implements "only-<platforms>" for tests headers using which one can
specify just the platforms on which the test should run rather than listing all
the platforms to ignore using "ignore-<platforms>".

This fixes rust-lang#33581 and fixes rust-lang#47459.

Remove incorrect `Default::default` links, add a new one

`map_or` and `map_or_else` don't use `Default::default`, but `unwrap_or_default` does.

…etrochenkov

Make non-found module name optional

No longer uses a magic string for missing or root module.

…on, r=estebank

rustc: Spawn `cmd /c` for `.bat` scripts

This fixes an accidental regression rust-lang#46335 where the behavior of
`Path::ends_with` is different from `str::ends_with` (paths operate over
components, strs operate over chars).

…k-Simulacrum

Update rust-installer for streaming parallelism

Pull in rust-lang/rust-installer#76 to get streamed tarball generation,
rather than batching it all in memory, while still getting the benefit
of compressing in parallel.

whitelist x86 fxsr feature

rust-lang#47223 properly checks that only white-listed features are allowed in combination with `target_feature`, but the `fxsr` feature used by `stdsimd` was not white-listed.

r? @alexcrichton