Auto merge of rust-lang#85443 - RalfJung:rollup-d9gd64t, r=RalfJung

Rollup of 7 pull requests

Successful merges:

 - rust-lang#84462 (rustdoc: use focus for search navigation)
 - rust-lang#85251 (Make `const_generics_defaults` not an incomplete feature)
 - rust-lang#85404 (Backport 1.52.1 release notes)
 - rust-lang#85407 (Improve display for "copy-path" button, making it more discreet)
 - rust-lang#85423 (Don't require cmake on Windows when LLVM isn't being built)
 - rust-lang#85428 (Add x.py pre-setup instructions)
 - rust-lang#85442 (fix typo)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup

README.md

@@ -19,8 +19,28 @@ Read ["Installation"] from [The Book].
 ## Installing from Source
 
 The Rust build system uses a Python script called `x.py` to build the compiler,
-which manages the bootstrapping process. More information about it can be found
-by running `./x.py --help` or reading the [rustc dev guide][rustcguidebuild].
+which manages the bootstrapping process. It lives in the root of the project.
+
+The `x.py` command can be run directly on most systems in the following format: 
+
+```sh
+./x.py <subcommand> [flags]
+```
+
+This is how the documentation and examples assume you are running `x.py`.
+
+Systems such as Ubuntu 20.04 LTS do not create the necessary `python` command by default when Python is installed that allows `x.py` to be run directly. In that case you can either create a symlink for `python` (Ubuntu provides the `python-is-python3` package for this), or run `x.py` using Python itself:
+
+```sh
+# Python 3
+python3 x.py <subcommand> [flags]
+
+# Python 2.7
+python2.7 x.py <subcommand> [flags]
+```
+
+More information about `x.py` can be found
+by running it with the `--help` flag or reading the [rustc dev guide][rustcguidebuild].
 
 [gettingstarted]: https://rustc-dev-guide.rust-lang.org/getting-started.html
 [rustcguidebuild]: https://rustc-dev-guide.rust-lang.org/building/how-to-build-and-run.html

RELEASES.md

@@ -1,3 +1,24 @@
+Version 1.52.1 (2021-05-10)
+============================
+
+This release disables incremental compilation, unless the user has explicitly
+opted in via the newly added RUSTC_FORCE_INCREMENTAL=1 environment variable.
+
+This is due to the widespread, and frequently occuring, breakage encountered by
+Rust users due to newly enabled incremental verification in 1.52.0. Notably,
+Rust users **should** upgrade to 1.52.0 or 1.52.1: the bugs that are detected by
+newly added incremental verification are still present in past stable versions,
+and are not yet fixed on any channel. These bugs can lead to miscompilation of
+Rust binaries.
+
+These problems only affect incremental builds, so release builds with Cargo
+should not be affected unless the user has explicitly opted into incremental.
+Debug and check builds are affected.
+
+See [84970] for more details.
+
+[84970]: https://github.com/rust-lang/rust/issues/84970
+
 Version 1.52.0 (2021-05-06)
 ============================
 

compiler/rustc_feature/src/active.rs

@@ -698,7 +698,6 @@ pub const INCOMPLETE_FEATURES: &[Symbol] = &[
     sym::repr128,
     sym::unsized_locals,
     sym::capture_disjoint_fields,
-    sym::const_generics_defaults,
     sym::inherent_associated_types,
     sym::type_alias_impl_trait,
     sym::native_link_modifiers,

library/std/src/io/mod.rs

@@ -1663,7 +1663,7 @@ pub trait Seek {
     ///
     /// # Errors
     ///
-    /// Seeking can fail, for example becaue it might involve flushing a buffer.
+    /// Seeking can fail, for example because it might involve flushing a buffer.
     ///
     /// Seeking to a negative offset is considered an error.
     #[stable(feature = "rust1", since = "1.0.0")]
@@ -1675,7 +1675,7 @@ pub trait Seek {
     ///
     /// # Errors
     ///
-    /// Rewinding can fail, for example becaue it might involve flushing a buffer.
+    /// Rewinding can fail, for example because it might involve flushing a buffer.
     ///
     /// # Example
     ///

src/bootstrap/sanity.rs

@@ -93,7 +93,8 @@ pub fn check(build: &mut Build) {
                     .unwrap_or(true)
             })
             .any(|build_llvm_ourselves| build_llvm_ourselves);
-    if building_llvm || build.config.any_sanitizers_enabled() {
+    let need_cmake = building_llvm || build.config.any_sanitizers_enabled();
+    if need_cmake {
         cmd_finder.must_have("cmake");
     }
 
@@ -204,7 +205,7 @@ pub fn check(build: &mut Build) {
             }
         }
 
-        if target.contains("msvc") {
+        if need_cmake && target.contains("msvc") {
             // There are three builds of cmake on windows: MSVC, MinGW, and
             // Cygwin. The Cygwin build does not have generators for Visual
             // Studio, so detect that here and error.

src/librustdoc/html/static/main.js

@@ -170,7 +170,8 @@ function hideThemeButtonState() {
         // 1 for "In Parameters"
         // 2 for "In Return Types"
         currentTab: 0,
-        mouseMovedAfterSearch: true,
+        // tab and back preserves the element that was focused.
+        focusedByTab: [null, null, null],
         clearInputTimeout: function() {
             if (searchState.timeout !== null) {
                 clearTimeout(searchState.timeout);
@@ -262,10 +263,6 @@ function hideThemeButtonState() {
                 search_input.placeholder = searchState.input.origPlaceholder;
             });
 
-            document.addEventListener("mousemove", function() {
-                searchState.mouseMovedAfterSearch = true;
-            });
-
             search_input.removeAttribute('disabled');
 
             // `crates{version}.js` should always be loaded before this script, so we can use it
@@ -1064,7 +1061,7 @@ function hideThemeButtonState() {
             ["T", "Focus the theme picker menu"],
             ["↑", "Move up in search results"],
             ["↓", "Move down in search results"],
-            ["ctrl + ↑ / ↓", "Switch result tab"],
+            ["← / →", "Switch result tab (when results focused)"],
             ["⏎", "Go to active search result"],
             ["+", "Expand all sections"],
             ["-", "Collapse all sections"],

src/librustdoc/html/static/rustdoc.css

@@ -144,7 +144,7 @@ h4.type.trait-impl, h4.associatedconstant.trait-impl, h4.associatedtype.trait-im
 }
 
 h1, h2, h3, h4,
-.sidebar, a.source, .search-input, .content table td:first-child > a,
+.sidebar, a.source, .search-input, .search-results .result-name,
 div.item-list .out-of-band,
 #source-sidebar, #sidebar-toggle,
 details.rustdoc-toggle > summary::before,
@@ -748,6 +748,15 @@ a {
 	outline: 0;
 }
 
+.search-results {
+	display: none;
+	padding-bottom: 2em;
+}
+
+.search-results.active {
+	display: block;
+}
+
 .search-results .desc {
 	white-space: nowrap;
 	text-overflow: ellipsis;
@@ -756,22 +765,14 @@ a {
 }
 
 .search-results a {
+	/* A little margin ensures the browser's outlining of focused links has room to display. */
+	margin-left: 2px;
+	margin-right: 2px;
 	display: block;
 }
 
-.content .search-results td:first-child {
-	padding-right: 0;
+.result-name {
 	width: 50%;
-}
-.content .search-results td:first-child a {
-	padding-right: 10px;
-}
-.content .search-results td:first-child a:after {
-	clear: both;
-	content: "";
-	display: block;
-}
-.content .search-results td:first-child a span {
 	float: left;
 }
 
@@ -1134,6 +1135,11 @@ pre.rust {
 .search-failed {
 	text-align: center;
 	margin-top: 20px;
+	display: none;
+}
+
+.search-failed.active {
+	display: block;
 }
 
 .search-failed > ul {
@@ -1262,12 +1268,11 @@ h4 > .notable-traits {
 }
 
 #copy-path {
+	background: initial;
 	margin-left: 10px;
 	padding: 0;
 	padding-left: 2px;
-}
-#copy-path> img {
-	margin-bottom: 2px;
+	border: 0;
 }
 
 #theme-choices {