Merge ref '5c49c4f7c839' from rust-lang/rust

Pull recent changes from https://github.com/rust-lang/rust via Josh.

Upstream ref: rust-lang/rust@5c49c4f
Filtered ref: 866efc3
Upstream diff: rust-lang/rust@44a5b55...5c49c4f

This merge was created using https://github.com/rust-lang/josh-sync.

Author: The rustc-josh-sync Cronjob Bot

src/tests/compiletest.md

@@ -78,6 +78,10 @@ The following test suites are available, with links for more information:
 
 [`run-make`](#run-make-tests) are general purpose tests using Rust programs.
 
+### The build-std test suite
+
+[`build-std`](#build-std-tests) test that -Zbuild-std works.
+
 ### Rustdoc test suites
 
 | Test suite                           | Purpose                                                                  |
@@ -429,6 +433,12 @@ use cases that require testing in-tree `cargo` in conjunction with in-tree `rust
 The `run-make` test suite does not have access to in-tree `cargo` (so it can be the
 faster-to-iterate test suite).
 
+### `build-std` tests
+
+The tests in [`tests/build-std`] check that `-Zbuild-std` works. This is currently
+just a run-make test suite with a single recipe. The recipe generates test cases
+and runs them in parallel.
+
 #### Using Rust recipes
 
 Each test should be in a separate directory with a `rmake.rs` Rust program,

src/tests/ui.md

@@ -139,6 +139,10 @@ prefixing each source line are replaced with `LL`). In extremely rare
 situations, this mode can be disabled with the directive `//@
 compile-flags: -Z ui-testing=no`.
 
+When using `-Z ui-testing=no` the `--diagnostic-width` argument should also
+be set to avoid tests failing or passing depending on the width of the terminal
+from which the UI test suite is being run.
+
 Note: The line and column numbers for `-->` lines pointing to the test are *not*
 normalized, and left as-is. This ensures that the compiler continues to point to
 the correct location, and keeps the stderr files readable. Ideally all