rust-lang · rust-bors · Aug 15, 2026 · Jul 26, 2026 · Feb 18, 2026 · Aug 12, 2026
diff --git a/library/core/src/iter/adapters/step_by.rs b/library/core/src/iter/adapters/step_by.rs
@@ -1,5 +1,5 @@
 use crate::intrinsics;
-use crate::iter::{TrustedLen, TrustedRandomAccess, from_fn};
+use crate::iter::{FusedIterator, TrustedLen, TrustedRandomAccess, from_fn};
 use crate::num::NonZero;
 use crate::ops::{Range, Try};
 use crate::range::RangeIter;
@@ -136,6 +136,11 @@ where
 #[stable(feature = "iterator_step_by", since = "1.28.0")]
 impl<I> ExactSizeIterator for StepBy<I> where I: ExactSizeIterator {}
 
+// StepBy stops yielding items once the underlying iterator does, so it is fused
+// whenever the underlying iterator is fused.
+#[stable(feature = "step_by_fused", since = "CURRENT_RUSTC_VERSION")]
+impl<I> FusedIterator for StepBy<I> where I: FusedIterator {}
+
 // SAFETY: This adapter is shortening. TrustedLen requires the upper bound to be calculated correctly.
 // These requirements can only be satisfied when the upper bound of the inner iterator's upper
 // bound is never `None`. I: TrustedRandomAccess happens to provide this guarantee while

diff --git a/library/coretests/tests/iter/adapters/step_by.rs b/library/coretests/tests/iter/adapters/step_by.rs
@@ -418,3 +418,16 @@ fn test_step_by_nth_non_fused_on_non_first_take() {
     // so we should expect `StepBy::nth` to return `None`
     assert_eq!(iter.nth(usize::MAX), None)
 }
+
+#[test]
+fn test_step_by_fused() {
+    // `StepBy` is fused whenever the underlying iterator is fused.
+    fn assert_fused<I: FusedIterator>(_: I) {}
+    assert_fused((0..10).step_by(3));
+
+    // Once the underlying fused iterator is exhausted, `StepBy` keeps yielding `None`.
+    let mut it = (0..3).step_by(5);
+    assert_eq!(it.next(), Some(0));
+    assert_eq!(it.next(), None);
+    assert_eq!(it.next(), None);
+}
diff --git a/src/doc/man/rustc.1 b/src/doc/man/rustc.1
@@ -62,7 +62,7 @@ Comma separated list of compiler information to print on stdout.
 Equivalent to \fI\-C\ debuginfo=2\fR.
 .TP
 \fB\-O\fR
-Equivalent to \fI\-C\ opt\-level=2\fR.
+Equivalent to \fI\-C\ opt\-level=3\fR.
 .TP
 \fB\-o\fR \fIFILENAME\fR
 Write output to \fIFILENAME\fR. Ignored if multiple \fI\-\-emit\fR outputs are specified which

diff --git a/src/doc/rustc-dev-guide/src/tests/ecosystem.md b/src/doc/rustc-dev-guide/src/tests/ecosystem.md
@@ -14,7 +14,7 @@ CI. See the [Crater chapter](crater.md) for more details.
 ### `cargotest`
 
 `cargotest` is a small tool which runs `cargo test` on a few sample projects
-(such as `servo`, `ripgrep`, `tokei`, etc.). This runs as part of CI and ensures
+(such as `stylo`, `ripgrep`, `tokei`, etc.). This runs as part of CI and ensures
 there aren't any significant regressions:
 
 ```console

diff --git a/src/tools/cargotest/main.rs b/src/tools/cargotest/main.rs
@@ -70,13 +70,11 @@ const TEST_REPOS: &[Test] = &[
         ],
     },
     Test {
-        name: "servo",
-        repo: "https://github.com/servo/servo",
-        sha: "785a344e32db58d4e631fd3cae17fd1f29a721ab",
+        name: "stylo",
+        repo: "https://github.com/servo/stylo",
+        sha: "127b0b5cab6a6927552e889debb20beb031b79d1",
         lock: None,
-        // Only test Stylo a.k.a. Quantum CSS, the parts of Servo going into Firefox.
-        // This takes much less time to build than all of Servo and supports stable Rust.
-        packages: &["selectors"],
+        packages: &["selectors", "stylo"],
         features: None,
         manifest_path: None,
         filters: &[],
@@ -213,10 +211,6 @@ fn run_cargo_test(
         .env("CFG_DISABLE_CROSS_TESTS", "1")
         // Relax #![deny(warnings)] in some crates
         .env("RUSTFLAGS", "--cap-lints warn")
-        // servo tries to use 'lld-link.exe' on windows, but we don't
-        // have lld on our PATH in CI. Override it to use 'link.exe'
-        .env("CARGO_TARGET_X86_64_PC_WINDOWS_MSVC_LINKER", "link.exe")
-        .env("CARGO_TARGET_I686_PC_WINDOWS_MSVC_LINKER", "link.exe")
         .current_dir(crate_path)
         .status()
         .unwrap();

diff --git a/tests/ui/consts/const-fn-vec-box-dyn-any-84170.rs b/tests/ui/consts/const-fn-vec-box-dyn-any-84170.rs
diff --git a/tests/ui/rust-2018/async-ident-allowed.rs b/tests/ui/rust-2018/async-ident-allowed.rs
@@ -1,4 +1,5 @@
 //@ edition:2015
+//@ reference: lex.keywords.strict.edition2018
 
 #![deny(rust_2018_compatibility)]
 

diff --git a/tests/ui/rust-2018/async-ident-allowed.stderr b/tests/ui/rust-2018/async-ident-allowed.stderr
@@ -1,13 +1,13 @@
 error: `async` is a keyword in the 2018 edition
-  --> $DIR/async-ident-allowed.rs:9:9
+  --> $DIR/async-ident-allowed.rs:10:9
    |
 LL |     let async = 3;
    |         ^^^^^ help: you can use a raw identifier to stay compatible: `r#async`
    |
    = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2018!
    = note: for more information, see <https://doc.rust-lang.org/edition-guide/rust-2018/new-keywords.html>
 note: the lint level is defined here
-  --> $DIR/async-ident-allowed.rs:3:9
+  --> $DIR/async-ident-allowed.rs:4:9
    |
 LL | #![deny(rust_2018_compatibility)]
    |         ^^^^^^^^^^^^^^^^^^^^^^^

diff --git a/tests/ui/rust-2018/async-ident.fixed b/tests/ui/rust-2018/async-ident.fixed
@@ -3,6 +3,8 @@
 
 //@ edition:2015
 //@ run-rustfix
+//@ reference: ident.raw.allowed
+//@ reference: lex.keywords.strict.edition2018
 
 fn r#async() {} //~ ERROR async
 //~^ WARN this is accepted in the current edition

diff --git a/tests/ui/rust-2018/async-ident.rs b/tests/ui/rust-2018/async-ident.rs
@@ -3,6 +3,8 @@
 
 //@ edition:2015
 //@ run-rustfix
+//@ reference: ident.raw.allowed
+//@ reference: lex.keywords.strict.edition2018
 
 fn async() {} //~ ERROR async
 //~^ WARN this is accepted in the current edition

diff --git a/tests/ui/rust-2018/async-ident.stderr b/tests/ui/rust-2018/async-ident.stderr
@@ -1,5 +1,5 @@
 error: `async` is a keyword in the 2018 edition
-  --> $DIR/async-ident.rs:7:4
+  --> $DIR/async-ident.rs:9:4
    |
 LL | fn async() {}
    |    ^^^^^ help: you can use a raw identifier to stay compatible: `r#async`
@@ -14,7 +14,7 @@ LL | #![deny(keyword_idents)]
    = note: `#[deny(keyword_idents_2018)]` implied by `#[deny(keyword_idents)]`
 
 error: `async` is a keyword in the 2018 edition
-  --> $DIR/async-ident.rs:12:19
+  --> $DIR/async-ident.rs:14:19
    |
 LL |     ($async:expr, async) => {};
    |                   ^^^^^ help: you can use a raw identifier to stay compatible: `r#async`
@@ -23,7 +23,7 @@ LL |     ($async:expr, async) => {};
    = note: for more information, see <https://doc.rust-lang.org/edition-guide/rust-2018/new-keywords.html>
 
 error: `async` is a keyword in the 2018 edition
-  --> $DIR/async-ident.rs:17:6
+  --> $DIR/async-ident.rs:19:6
    |
 LL | foo!(async);
    |      ^^^^^ help: you can use a raw identifier to stay compatible: `r#async`
@@ -32,7 +32,7 @@ LL | foo!(async);
    = note: for more information, see <https://doc.rust-lang.org/edition-guide/rust-2018/new-keywords.html>
 
 error: `async` is a keyword in the 2018 edition
-  --> $DIR/async-ident.rs:26:11
+  --> $DIR/async-ident.rs:28:11
    |
 LL |     trait async {}
    |           ^^^^^ help: you can use a raw identifier to stay compatible: `r#async`
@@ -41,7 +41,7 @@ LL |     trait async {}
    = note: for more information, see <https://doc.rust-lang.org/edition-guide/rust-2018/new-keywords.html>
 
 error: `async` is a keyword in the 2018 edition
-  --> $DIR/async-ident.rs:30:10
+  --> $DIR/async-ident.rs:32:10
    |
 LL |     impl async for MyStruct {}
    |          ^^^^^ help: you can use a raw identifier to stay compatible: `r#async`
@@ -50,7 +50,7 @@ LL |     impl async for MyStruct {}
    = note: for more information, see <https://doc.rust-lang.org/edition-guide/rust-2018/new-keywords.html>
 
 error: `async` is a keyword in the 2018 edition
-  --> $DIR/async-ident.rs:36:12
+  --> $DIR/async-ident.rs:38:12
    |
 LL |     static async: u32 = 0;
    |            ^^^^^ help: you can use a raw identifier to stay compatible: `r#async`
@@ -59,7 +59,7 @@ LL |     static async: u32 = 0;
    = note: for more information, see <https://doc.rust-lang.org/edition-guide/rust-2018/new-keywords.html>
 
 error: `async` is a keyword in the 2018 edition
-  --> $DIR/async-ident.rs:42:11
+  --> $DIR/async-ident.rs:44:11
    |
 LL |     const async: u32 = 0;
    |           ^^^^^ help: you can use a raw identifier to stay compatible: `r#async`
@@ -68,7 +68,7 @@ LL |     const async: u32 = 0;
    = note: for more information, see <https://doc.rust-lang.org/edition-guide/rust-2018/new-keywords.html>
 
 error: `async` is a keyword in the 2018 edition
-  --> $DIR/async-ident.rs:48:15
+  --> $DIR/async-ident.rs:50:15
    |
 LL | impl Foo { fn async() {} }
    |               ^^^^^ help: you can use a raw identifier to stay compatible: `r#async`
@@ -77,7 +77,7 @@ LL | impl Foo { fn async() {} }
    = note: for more information, see <https://doc.rust-lang.org/edition-guide/rust-2018/new-keywords.html>
 
 error: `async` is a keyword in the 2018 edition
-  --> $DIR/async-ident.rs:53:12
+  --> $DIR/async-ident.rs:55:12
    |
 LL |     struct async {}
    |            ^^^^^ help: you can use a raw identifier to stay compatible: `r#async`
@@ -86,7 +86,7 @@ LL |     struct async {}
    = note: for more information, see <https://doc.rust-lang.org/edition-guide/rust-2018/new-keywords.html>
 
 error: `async` is a keyword in the 2018 edition
-  --> $DIR/async-ident.rs:56:9
+  --> $DIR/async-ident.rs:58:9
    |
 LL |     let async: async = async {};
    |         ^^^^^ help: you can use a raw identifier to stay compatible: `r#async`
@@ -95,7 +95,7 @@ LL |     let async: async = async {};
    = note: for more information, see <https://doc.rust-lang.org/edition-guide/rust-2018/new-keywords.html>
 
 error: `async` is a keyword in the 2018 edition
-  --> $DIR/async-ident.rs:56:16
+  --> $DIR/async-ident.rs:58:16
    |
 LL |     let async: async = async {};
    |                ^^^^^ help: you can use a raw identifier to stay compatible: `r#async`
@@ -104,7 +104,7 @@ LL |     let async: async = async {};
    = note: for more information, see <https://doc.rust-lang.org/edition-guide/rust-2018/new-keywords.html>
 
 error: `async` is a keyword in the 2018 edition
-  --> $DIR/async-ident.rs:56:24
+  --> $DIR/async-ident.rs:58:24
    |
 LL |     let async: async = async {};
    |                        ^^^^^ help: you can use a raw identifier to stay compatible: `r#async`
@@ -113,7 +113,7 @@ LL |     let async: async = async {};
    = note: for more information, see <https://doc.rust-lang.org/edition-guide/rust-2018/new-keywords.html>
 
 error: `async` is a keyword in the 2018 edition
-  --> $DIR/async-ident.rs:67:19
+  --> $DIR/async-ident.rs:69:19
    |
 LL |     () => (pub fn async() {})
    |                   ^^^^^ help: you can use a raw identifier to stay compatible: `r#async`
@@ -122,7 +122,7 @@ LL |     () => (pub fn async() {})
    = note: for more information, see <https://doc.rust-lang.org/edition-guide/rust-2018/new-keywords.html>
 
 error: `async` is a keyword in the 2018 edition
-  --> $DIR/async-ident.rs:74:6
+  --> $DIR/async-ident.rs:76:6
    |
 LL |     (async) => (1)
    |      ^^^^^ help: you can use a raw identifier to stay compatible: `r#async`

diff --git a/tests/ui/rust-2018/dyn-keyword.fixed b/tests/ui/rust-2018/dyn-keyword.fixed
@@ -1,5 +1,7 @@
 //@ edition:2015
 //@ run-rustfix
+//@ reference: ident.raw.allowed
+//@ reference: lex.keywords.strict.edition2018
 
 #![allow(unused_variables)]
 #![deny(keyword_idents)]

diff --git a/tests/ui/rust-2018/dyn-keyword.rs b/tests/ui/rust-2018/dyn-keyword.rs
@@ -1,5 +1,7 @@
 //@ edition:2015
 //@ run-rustfix
+//@ reference: ident.raw.allowed
+//@ reference: lex.keywords.strict.edition2018
 
 #![allow(unused_variables)]
 #![deny(keyword_idents)]

diff --git a/tests/ui/rust-2018/dyn-keyword.stderr b/tests/ui/rust-2018/dyn-keyword.stderr
@@ -1,13 +1,13 @@
 error: `dyn` is a keyword in the 2018 edition
-  --> $DIR/dyn-keyword.rs:8:9
+  --> $DIR/dyn-keyword.rs:10:9
    |
 LL |     let dyn = ();
    |         ^^^ help: you can use a raw identifier to stay compatible: `r#dyn`
    |
    = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2018!
    = note: for more information, see <https://doc.rust-lang.org/edition-guide/rust-2018/new-keywords.html>
 note: the lint level is defined here
-  --> $DIR/dyn-keyword.rs:5:9
+  --> $DIR/dyn-keyword.rs:7:9
    |
 LL | #![deny(keyword_idents)]
    |         ^^^^^^^^^^^^^^

diff --git a/tests/ui/rust-2018/edition-lint-fully-qualified-paths.fixed b/tests/ui/rust-2018/edition-lint-fully-qualified-paths.fixed
@@ -1,5 +1,6 @@
 //@ edition: 2015
 //@ run-rustfix
+//@ reference: paths.qualifiers.global-root.edition2018
 
 #![deny(absolute_paths_not_starting_with_crate)]
 

diff --git a/tests/ui/rust-2018/edition-lint-fully-qualified-paths.rs b/tests/ui/rust-2018/edition-lint-fully-qualified-paths.rs
@@ -1,5 +1,6 @@
 //@ edition: 2015
 //@ run-rustfix
+//@ reference: paths.qualifiers.global-root.edition2018
 
 #![deny(absolute_paths_not_starting_with_crate)]
 

diff --git a/tests/ui/rust-2018/edition-lint-fully-qualified-paths.stderr b/tests/ui/rust-2018/edition-lint-fully-qualified-paths.stderr
@@ -1,19 +1,19 @@
 error: absolute paths must start with `self`, `super`, `crate`, or an external crate name in the 2018 edition
-  --> $DIR/edition-lint-fully-qualified-paths.rs:19:25
+  --> $DIR/edition-lint-fully-qualified-paths.rs:20:25
    |
 LL |     let _: <foo::Baz as ::foo::Foo>::Bar = ();
    |                         ^^^^^^^^^^ help: use `crate`: `crate::foo::Foo`
    |
    = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2018!
    = note: for more information, see <https://doc.rust-lang.org/edition-guide/rust-2018/path-changes.html>
 note: the lint level is defined here
-  --> $DIR/edition-lint-fully-qualified-paths.rs:4:9
+  --> $DIR/edition-lint-fully-qualified-paths.rs:5:9
    |
 LL | #![deny(absolute_paths_not_starting_with_crate)]
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: absolute paths must start with `self`, `super`, `crate`, or an external crate name in the 2018 edition
-  --> $DIR/edition-lint-fully-qualified-paths.rs:19:25
+  --> $DIR/edition-lint-fully-qualified-paths.rs:20:25
    |
 LL |     let _: <foo::Baz as ::foo::Foo>::Bar = ();
    |                         ^^^^^^^^^^ help: use `crate`: `crate::foo::Foo`
@@ -23,7 +23,7 @@ LL |     let _: <foo::Baz as ::foo::Foo>::Bar = ();
    = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
 error: absolute paths must start with `self`, `super`, `crate`, or an external crate name in the 2018 edition
-  --> $DIR/edition-lint-fully-qualified-paths.rs:25:13
+  --> $DIR/edition-lint-fully-qualified-paths.rs:26:13
    |
 LL |     let _: <::foo::Baz as foo::Foo>::Bar = ();
    |             ^^^^^^^^^^ help: use `crate`: `crate::foo::Baz`

diff --git a/tests/ui/rust-2018/edition-lint-paths.fixed b/tests/ui/rust-2018/edition-lint-paths.fixed
@@ -1,6 +1,7 @@
 //@ edition: 2015
 //@ aux-build:edition-lint-paths.rs
 //@ run-rustfix
+//@ reference: paths.qualifiers.global-root.edition2018
 
 #![deny(absolute_paths_not_starting_with_crate)]
 #![allow(unused)]

diff --git a/tests/ui/rust-2018/edition-lint-paths.rs b/tests/ui/rust-2018/edition-lint-paths.rs
@@ -1,6 +1,7 @@
 //@ edition: 2015
 //@ aux-build:edition-lint-paths.rs
 //@ run-rustfix
+//@ reference: paths.qualifiers.global-root.edition2018
 
 #![deny(absolute_paths_not_starting_with_crate)]
 #![allow(unused)]