core and alloc doctests support doctest merging

library/alloc/src/lib.rs

diff --git a/library/alloc/src/lib.rs b/library/alloc/src/lib.rs
index 73e9365..7ac9cdc 100644
--- a/library/alloc/src/lib.rs
+++ b/library/alloc/src/lib.rs
@@ -63,7 +63,7 @@
 #![doc(
     html_playground_url = "https://play.rust-lang.org/",
     issue_tracker_base_url = "https://github.com/rust-lang/rust/issues/",
-    test(no_crate_inject, attr(allow(unused_variables), deny(warnings)))
+    test(no_crate_inject, attr(allow(unused_variables, duplicate_features), deny(warnings)))
 )]
 #![doc(auto_cfg(hide(no_global_oom_handling, no_rc, no_sync, target_has_atomic = "ptr")))]
 #![doc(rust_logo)]

library/core/src/alloc/global.rs

diff --git a/library/core/src/alloc/global.rs b/library/core/src/alloc/global.rs
index bf3d3e0..e97398a 100644
--- a/library/core/src/alloc/global.rs
+++ b/library/core/src/alloc/global.rs
@@ -19,7 +19,7 @@
 ///
 /// # Example
 ///
-/// ```
+/// ```standalone_crate
 /// use std::alloc::{GlobalAlloc, Layout};
 /// use std::cell::UnsafeCell;
 /// use std::ptr::null_mut;

library/core/src/hint.rs

diff --git a/library/core/src/hint.rs b/library/core/src/hint.rs
index 03ed04d..a8e01e6 100644
--- a/library/core/src/hint.rs
+++ b/library/core/src/hint.rs
@@ -514,7 +514,7 @@ pub const fn black_box<T>(dummy: T) -> T {
 /// macro_rules! make_error {
 ///     ($($args:expr),*) => {
 ///         core::hint::must_use({
-///             let error = $crate::make_error(core::format_args!($($args),*));
+///             let error = make_error(core::format_args!($($args),*));
 ///             error
 ///         })
 ///     };

library/core/src/lib.rs

diff --git a/library/core/src/lib.rs b/library/core/src/lib.rs
index 29869dd..e12c430 100644
--- a/library/core/src/lib.rs
+++ b/library/core/src/lib.rs
@@ -48,7 +48,7 @@
     html_playground_url = "https://play.rust-lang.org/",
     issue_tracker_base_url = "https://github.com/rust-lang/rust/issues/",
     test(no_crate_inject, attr(deny(warnings))),
-    test(attr(allow(dead_code, deprecated, unused_variables, unused_mut)))
+    test(attr(allow(dead_code, deprecated, unused_variables, unused_mut, duplicate_features)))
 )]
 #![doc(rust_logo)]
 #![doc(auto_cfg(hide(

library/core/src/range.rs

diff --git a/library/core/src/range.rs b/library/core/src/range.rs
index d12a4ef..3c2c40d 100644
--- a/library/core/src/range.rs
+++ b/library/core/src/range.rs
@@ -584,7 +584,7 @@ fn from(value: legacy::RangeFrom<T>) -> Self {
 ///
 /// The `..=last` syntax is a `RangeToInclusive`:
 ///
-/// ```
+/// ```standalone_crate
 /// #![feature(new_range)]
 /// assert_eq!((..=5), std::range::RangeToInclusive { last: 5 });
 /// ```