From 638b226a6ab5c5c784955068f57ae249e0ed0f92 Mon Sep 17 00:00:00 2001
From: Thalia Archibald <thalia@archibald.dev>
Date: Wed, 5 Mar 2025 18:14:07 -0800
Subject: [PATCH] Remove #[cfg(not(test))] gates in core

These gates are unnecessary now that unit tests for `core` are in a
separate package, `coretests`, instead of in the same files as the
source code. They previously prevented the two `core` versions from
conflicting with each other.
---
 ...0027-stdlib-128bit-atomic-operations.patch | 24 ++++++++---------
 library/core/src/any.rs                       |  2 +-
 library/core/src/array/ascii.rs               |  1 -
 library/core/src/bool.rs                      |  2 +-
 library/core/src/cell.rs                      |  4 +--
 library/core/src/char/methods.rs              |  2 +-
 library/core/src/cmp.rs                       |  4 +--
 library/core/src/convert/mod.rs               |  4 +--
 library/core/src/default.rs                   |  2 +-
 library/core/src/error.rs                     |  2 +-
 library/core/src/fmt/mod.rs                   |  2 +-
 library/core/src/iter/adapters/enumerate.rs   |  2 +-
 library/core/src/iter/sources/repeat.rs       |  2 +-
 library/core/src/iter/traits/double_ended.rs  |  2 +-
 library/core/src/iter/traits/iterator.rs      | 10 +++----
 library/core/src/lib.rs                       | 17 ------------
 library/core/src/macros/mod.rs                | 26 +++++++++----------
 library/core/src/marker.rs                    |  6 ++---
 library/core/src/mem/mod.rs                   | 12 ++++-----
 library/core/src/net/ip_addr.rs               |  2 +-
 library/core/src/num/f128.rs                  |  5 +---
 library/core/src/num/f16.rs                   |  5 +---
 library/core/src/num/f32.rs                   |  7 ++---
 library/core/src/num/f64.rs                   |  7 ++---
 library/core/src/ops/control_flow.rs          |  2 +-
 library/core/src/option.rs                    |  4 +--
 library/core/src/panic/unwind_safe.rs         |  4 +--
 library/core/src/result.rs                    |  2 +-
 library/core/src/slice/ascii.rs               |  1 -
 library/core/src/slice/mod.rs                 |  5 +---
 library/core/src/str/mod.rs                   | 17 ++++++------
 library/core/src/sync/atomic.rs               | 26 +++++++++----------
 library/core/src/task/wake.rs                 |  2 +-
 library/core/src/time.rs                      |  2 +-
 34 files changed, 90 insertions(+), 127 deletions(-)

diff --git a/compiler/rustc_codegen_cranelift/patches/0027-stdlib-128bit-atomic-operations.patch b/compiler/rustc_codegen_cranelift/patches/0027-stdlib-128bit-atomic-operations.patch
index 3c81b04c0ead2..d7e3b11127c42 100644
--- a/compiler/rustc_codegen_cranelift/patches/0027-stdlib-128bit-atomic-operations.patch
+++ b/compiler/rustc_codegen_cranelift/patches/0027-stdlib-128bit-atomic-operations.patch
@@ -1,4 +1,4 @@
-From ad7ffe71baba46865f2e65266ab025920dfdc20b Mon Sep 17 00:00:00 2001
+From 5d7c709608b01301d4628d2159265936d4440b67 Mon Sep 17 00:00:00 2001
 From: bjorn3 <bjorn3@users.noreply.github.com>
 Date: Thu, 18 Feb 2021 18:45:28 +0100
 Subject: [PATCH] Disable 128bit atomic operations
@@ -7,11 +7,10 @@ Cranelift doesn't support them yet
 ---
  library/core/src/panic/unwind_safe.rs |  6 -----
  library/core/src/sync/atomic.rs       | 38 ---------------------------
- library/core/tests/atomic.rs          |  4 ---
- 4 files changed, 4 insertions(+), 50 deletions(-)
+ 2 files changed, 44 deletions(-)
 
 diff --git a/library/core/src/panic/unwind_safe.rs b/library/core/src/panic/unwind_safe.rs
-index 092b7cf..158cf71 100644
+index a60f0799c0e..af056fbf41f 100644
 --- a/library/core/src/panic/unwind_safe.rs
 +++ b/library/core/src/panic/unwind_safe.rs
 @@ -216,9 +216,6 @@ impl RefUnwindSafe for crate::sync::atomic::AtomicI32 {}
@@ -21,7 +20,7 @@ index 092b7cf..158cf71 100644
 -#[cfg(target_has_atomic_load_store = "128")]
 -#[unstable(feature = "integer_atomics", issue = "99069")]
 -impl RefUnwindSafe for crate::sync::atomic::AtomicI128 {}
-
+ 
  #[cfg(target_has_atomic_load_store = "ptr")]
  #[stable(feature = "unwind_safe_atomic_refs", since = "1.14.0")]
 @@ -235,9 +232,6 @@ impl RefUnwindSafe for crate::sync::atomic::AtomicU32 {}
@@ -31,14 +30,14 @@ index 092b7cf..158cf71 100644
 -#[cfg(target_has_atomic_load_store = "128")]
 -#[unstable(feature = "integer_atomics", issue = "99069")]
 -impl RefUnwindSafe for crate::sync::atomic::AtomicU128 {}
-
+ 
  #[cfg(target_has_atomic_load_store = "8")]
  #[stable(feature = "unwind_safe_atomic_refs", since = "1.14.0")]
 diff --git a/library/core/src/sync/atomic.rs b/library/core/src/sync/atomic.rs
-index d9de37e..8293fce 100644
+index bf2b6d59f88..d5ccce03bbf 100644
 --- a/library/core/src/sync/atomic.rs
 +++ b/library/core/src/sync/atomic.rs
-@@ -2996,44 +2996,6 @@ atomic_int! {
+@@ -3585,44 +3585,6 @@ pub const fn as_ptr(&self) -> *mut $int_type {
      8,
      u64 AtomicU64
  }
@@ -54,7 +53,7 @@ index d9de37e..8293fce 100644
 -    unstable(feature = "integer_atomics", issue = "99069"),
 -    rustc_const_unstable(feature = "integer_atomics", issue = "99069"),
 -    rustc_const_unstable(feature = "integer_atomics", issue = "99069"),
--    cfg_attr(not(test), rustc_diagnostic_item = "AtomicI128"),
+-    rustc_diagnostic_item = "AtomicI128",
 -    "i128",
 -    "#![feature(integer_atomics)]\n\n",
 -    atomic_min, atomic_max,
@@ -73,7 +72,7 @@ index d9de37e..8293fce 100644
 -    unstable(feature = "integer_atomics", issue = "99069"),
 -    rustc_const_unstable(feature = "integer_atomics", issue = "99069"),
 -    rustc_const_unstable(feature = "integer_atomics", issue = "99069"),
--    cfg_attr(not(test), rustc_diagnostic_item = "AtomicU128"),
+-    rustc_diagnostic_item = "AtomicU128",
 -    "u128",
 -    "#![feature(integer_atomics)]\n\n",
 -    atomic_umin, atomic_umax,
@@ -83,7 +82,6 @@ index d9de37e..8293fce 100644
  
  #[cfg(target_has_atomic_load_store = "ptr")]
  macro_rules! atomic_int_ptr_sized {
-     ( $($target_pointer_width:literal $align:literal)* ) => { $(
---
-2.26.2.7.g19db9cfb68
+-- 
+2.48.1
 
diff --git a/library/core/src/any.rs b/library/core/src/any.rs
index 9ed2c8e9f3ad1..10f2a11d558be 100644
--- a/library/core/src/any.rs
+++ b/library/core/src/any.rs
@@ -109,7 +109,7 @@ use crate::{fmt, hash, intrinsics};
 // unsafe traits and unsafe methods (i.e., `type_id` would still be safe to call,
 // but we would likely want to indicate as such in documentation).
 #[stable(feature = "rust1", since = "1.0.0")]
-#[cfg_attr(not(test), rustc_diagnostic_item = "Any")]
+#[rustc_diagnostic_item = "Any"]
 pub trait Any: 'static {
     /// Gets the `TypeId` of `self`.
     ///
diff --git a/library/core/src/array/ascii.rs b/library/core/src/array/ascii.rs
index e2faef855bc2c..792a57e3fa25c 100644
--- a/library/core/src/array/ascii.rs
+++ b/library/core/src/array/ascii.rs
@@ -1,6 +1,5 @@
 use crate::ascii;
 
-#[cfg(not(test))]
 impl<const N: usize> [u8; N] {
     /// Converts this array of bytes into an array of ASCII characters,
     /// or returns `None` if any of the characters is non-ASCII.
diff --git a/library/core/src/bool.rs b/library/core/src/bool.rs
index 3c589ca5dfa7e..d525ab425e60d 100644
--- a/library/core/src/bool.rs
+++ b/library/core/src/bool.rs
@@ -56,7 +56,7 @@ impl bool {
     /// ```
     #[doc(alias = "then_with")]
     #[stable(feature = "lazy_bool_to_option", since = "1.50.0")]
-    #[cfg_attr(not(test), rustc_diagnostic_item = "bool_then")]
+    #[rustc_diagnostic_item = "bool_then"]
     #[inline]
     pub fn then<T, F: FnOnce() -> T>(self, f: F) -> Option<T> {
         if self { Some(f()) } else { None }
diff --git a/library/core/src/cell.rs b/library/core/src/cell.rs
index cbf00106c5173..1a320b316a41a 100644
--- a/library/core/src/cell.rs
+++ b/library/core/src/cell.rs
@@ -304,7 +304,7 @@ pub use once::OnceCell;
 /// ```
 ///
 /// See the [module-level documentation](self) for more.
-#[cfg_attr(not(test), rustc_diagnostic_item = "Cell")]
+#[rustc_diagnostic_item = "Cell"]
 #[stable(feature = "rust1", since = "1.0.0")]
 #[repr(transparent)]
 #[rustc_pub_transparent]
@@ -725,7 +725,7 @@ impl<T, const N: usize> Cell<[T; N]> {
 /// A mutable memory location with dynamically checked borrow rules
 ///
 /// See the [module-level documentation](self) for more.
-#[cfg_attr(not(test), rustc_diagnostic_item = "RefCell")]
+#[rustc_diagnostic_item = "RefCell"]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct RefCell<T: ?Sized> {
     borrow: Cell<BorrowFlag>,
diff --git a/library/core/src/char/methods.rs b/library/core/src/char/methods.rs
index 85cc315626d4b..dc076a7cce50a 100644
--- a/library/core/src/char/methods.rs
+++ b/library/core/src/char/methods.rs
@@ -1178,7 +1178,7 @@ impl char {
     #[must_use]
     #[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
     #[rustc_const_stable(feature = "const_char_is_ascii", since = "1.32.0")]
-    #[cfg_attr(not(test), rustc_diagnostic_item = "char_is_ascii")]
+    #[rustc_diagnostic_item = "char_is_ascii"]
     #[inline]
     pub const fn is_ascii(&self) -> bool {
         *self as u32 <= 0x7F
diff --git a/library/core/src/cmp.rs b/library/core/src/cmp.rs
index c8ced78c4d791..582138d6c9241 100644
--- a/library/core/src/cmp.rs
+++ b/library/core/src/cmp.rs
@@ -1471,7 +1471,7 @@ pub macro PartialOrd($item:item) {
 #[inline]
 #[must_use]
 #[stable(feature = "rust1", since = "1.0.0")]
-#[cfg_attr(not(test), rustc_diagnostic_item = "cmp_min")]
+#[rustc_diagnostic_item = "cmp_min"]
 pub fn min<T: Ord>(v1: T, v2: T) -> T {
     v1.min(v2)
 }
@@ -1563,7 +1563,7 @@ pub fn min_by_key<T, F: FnMut(&T) -> K, K: Ord>(v1: T, v2: T, mut f: F) -> T {
 #[inline]
 #[must_use]
 #[stable(feature = "rust1", since = "1.0.0")]
-#[cfg_attr(not(test), rustc_diagnostic_item = "cmp_max")]
+#[rustc_diagnostic_item = "cmp_max"]
 pub fn max<T: Ord>(v1: T, v2: T) -> T {
     v1.max(v2)
 }
diff --git a/library/core/src/convert/mod.rs b/library/core/src/convert/mod.rs
index e468f4f0f7e66..cfa9ae73f2d2d 100644
--- a/library/core/src/convert/mod.rs
+++ b/library/core/src/convert/mod.rs
@@ -214,7 +214,7 @@ pub const fn identity<T>(x: T) -> T {
 /// is_hello(s);
 /// ```
 #[stable(feature = "rust1", since = "1.0.0")]
-#[cfg_attr(not(test), rustc_diagnostic_item = "AsRef")]
+#[rustc_diagnostic_item = "AsRef"]
 pub trait AsRef<T: ?Sized> {
     /// Converts this type into a shared reference of the (usually inferred) input type.
     #[stable(feature = "rust1", since = "1.0.0")]
@@ -365,7 +365,7 @@ pub trait AsRef<T: ?Sized> {
 /// Note, however, that APIs don't need to be generic. In many cases taking a `&mut [u8]` or
 /// `&mut Vec<u8>`, for example, is the better choice (callers need to pass the correct type then).
 #[stable(feature = "rust1", since = "1.0.0")]
-#[cfg_attr(not(test), rustc_diagnostic_item = "AsMut")]
+#[rustc_diagnostic_item = "AsMut"]
 pub trait AsMut<T: ?Sized> {
     /// Converts this type into a mutable reference of the (usually inferred) input type.
     #[stable(feature = "rust1", since = "1.0.0")]
diff --git a/library/core/src/default.rs b/library/core/src/default.rs
index 4c30290ff263b..044997a81a9a2 100644
--- a/library/core/src/default.rs
+++ b/library/core/src/default.rs
@@ -101,7 +101,7 @@ use crate::ascii::Char as AsciiChar;
 ///     bar: f32,
 /// }
 /// ```
-#[cfg_attr(not(test), rustc_diagnostic_item = "Default")]
+#[rustc_diagnostic_item = "Default"]
 #[stable(feature = "rust1", since = "1.0.0")]
 #[rustc_trivial_field_reads]
 pub trait Default: Sized {
diff --git a/library/core/src/error.rs b/library/core/src/error.rs
index 94847685ec965..bfa392003b91b 100644
--- a/library/core/src/error.rs
+++ b/library/core/src/error.rs
@@ -47,7 +47,7 @@ use crate::fmt::{self, Debug, Display, Formatter};
 /// impl Error for ReadConfigError {}
 /// ```
 #[stable(feature = "rust1", since = "1.0.0")]
-#[cfg_attr(not(test), rustc_diagnostic_item = "Error")]
+#[rustc_diagnostic_item = "Error"]
 #[rustc_has_incoherent_inherent_impls]
 #[allow(multiple_supertrait_upcastable)]
 pub trait Error: Debug + Display {
diff --git a/library/core/src/fmt/mod.rs b/library/core/src/fmt/mod.rs
index 3f60bb067d6e6..bd7566e48f82d 100644
--- a/library/core/src/fmt/mod.rs
+++ b/library/core/src/fmt/mod.rs
@@ -18,7 +18,7 @@ mod num;
 mod rt;
 
 #[stable(feature = "fmt_flags_align", since = "1.28.0")]
-#[cfg_attr(not(test), rustc_diagnostic_item = "Alignment")]
+#[rustc_diagnostic_item = "Alignment"]
 /// Possible alignments returned by `Formatter::align`
 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
 pub enum Alignment {
diff --git a/library/core/src/iter/adapters/enumerate.rs b/library/core/src/iter/adapters/enumerate.rs
index ac15e3767fc09..f9c388e8564d3 100644
--- a/library/core/src/iter/adapters/enumerate.rs
+++ b/library/core/src/iter/adapters/enumerate.rs
@@ -14,7 +14,7 @@ use crate::ops::Try;
 #[derive(Clone, Debug)]
 #[must_use = "iterators are lazy and do nothing unless consumed"]
 #[stable(feature = "rust1", since = "1.0.0")]
-#[cfg_attr(not(test), rustc_diagnostic_item = "Enumerate")]
+#[rustc_diagnostic_item = "Enumerate"]
 pub struct Enumerate<I> {
     iter: I,
     count: usize,
diff --git a/library/core/src/iter/sources/repeat.rs b/library/core/src/iter/sources/repeat.rs
index 243f938bce2af..c4f5a483e5c2a 100644
--- a/library/core/src/iter/sources/repeat.rs
+++ b/library/core/src/iter/sources/repeat.rs
@@ -56,7 +56,7 @@ use crate::num::NonZero;
 /// ```
 #[inline]
 #[stable(feature = "rust1", since = "1.0.0")]
-#[cfg_attr(not(test), rustc_diagnostic_item = "iter_repeat")]
+#[rustc_diagnostic_item = "iter_repeat"]
 pub fn repeat<T: Clone>(elt: T) -> Repeat<T> {
     Repeat { element: elt }
 }
diff --git a/library/core/src/iter/traits/double_ended.rs b/library/core/src/iter/traits/double_ended.rs
index 3b12678572841..7dabaece95561 100644
--- a/library/core/src/iter/traits/double_ended.rs
+++ b/library/core/src/iter/traits/double_ended.rs
@@ -37,7 +37,7 @@ use crate::ops::{ControlFlow, Try};
 /// assert_eq!(None, iter.next_back());
 /// ```
 #[stable(feature = "rust1", since = "1.0.0")]
-#[cfg_attr(not(test), rustc_diagnostic_item = "DoubleEndedIterator")]
+#[rustc_diagnostic_item = "DoubleEndedIterator"]
 pub trait DoubleEndedIterator: Iterator {
     /// Removes and returns an element from the end of the iterator.
     ///
diff --git a/library/core/src/iter/traits/iterator.rs b/library/core/src/iter/traits/iterator.rs
index 42886e90f997d..f22d03525d5f9 100644
--- a/library/core/src/iter/traits/iterator.rs
+++ b/library/core/src/iter/traits/iterator.rs
@@ -862,7 +862,7 @@ pub trait Iterator {
     /// Note that `iter.filter(f).next()` is equivalent to `iter.find(f)`.
     #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[cfg_attr(not(test), rustc_diagnostic_item = "iter_filter")]
+    #[rustc_diagnostic_item = "iter_filter"]
     fn filter<P>(self, predicate: P) -> Filter<Self, P>
     where
         Self: Sized,
@@ -954,7 +954,7 @@ pub trait Iterator {
     /// ```
     #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[cfg_attr(not(test), rustc_diagnostic_item = "enumerate_method")]
+    #[rustc_diagnostic_item = "enumerate_method"]
     fn enumerate(self) -> Enumerate<Self>
     where
         Self: Sized,
@@ -1963,7 +1963,7 @@ pub trait Iterator {
     #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]
     #[must_use = "if you really need to exhaust the iterator, consider `.for_each(drop)` instead"]
-    #[cfg_attr(not(test), rustc_diagnostic_item = "iterator_collect_fn")]
+    #[rustc_diagnostic_item = "iterator_collect_fn"]
     fn collect<B: FromIterator<Self::Item>>(self) -> B
     where
         Self: Sized,
@@ -3358,7 +3358,7 @@ pub trait Iterator {
     /// assert_eq!(v_map, vec![1, 2, 3]);
     /// ```
     #[stable(feature = "iter_copied", since = "1.36.0")]
-    #[cfg_attr(not(test), rustc_diagnostic_item = "iter_copied")]
+    #[rustc_diagnostic_item = "iter_copied"]
     fn copied<'a, T: 'a>(self) -> Copied<Self>
     where
         Self: Sized + Iterator<Item = &'a T>,
@@ -3406,7 +3406,7 @@ pub trait Iterator {
     /// assert_eq!(&[vec![23]], &faster[..]);
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[cfg_attr(not(test), rustc_diagnostic_item = "iter_cloned")]
+    #[rustc_diagnostic_item = "iter_cloned"]
     fn cloned<'a, T: 'a>(self) -> Cloned<Self>
     where
         Self: Sized + Iterator<Item = &'a T>,
diff --git a/library/core/src/lib.rs b/library/core/src/lib.rs
index db68f472c42f6..620db4445fce6 100644
--- a/library/core/src/lib.rs
+++ b/library/core/src/lib.rs
@@ -43,18 +43,6 @@
 //!    which do not trigger a panic can be assured that this function is never
 //!    called. The `lang` attribute is called `eh_personality`.
 
-// Since core defines many fundamental lang items, all tests live in a
-// separate crate, coretests (library/coretests), to avoid bizarre issues.
-//
-// Here we explicitly #[cfg]-out this whole crate when testing. If we don't do
-// this, both the generated test artifact and the linked libtest (which
-// transitively includes core) will both define the same set of lang items,
-// and this will cause the E0152 "found duplicate lang item" error. See
-// discussion in #50466 for details.
-//
-// This cfg won't affect doc tests.
-#![cfg(not(test))]
-//
 #![stable(feature = "core", since = "1.6.0")]
 #![doc(
     html_playground_url = "https://play.rust-lang.org/",
@@ -64,7 +52,6 @@
 )]
 #![doc(rust_logo)]
 #![doc(cfg_hide(
-    not(test),
     no_fp_fmt_parse,
     target_pointer_width = "16",
     target_pointer_width = "32",
@@ -225,13 +212,9 @@ extern crate self as core;
 #[allow(unused)]
 use prelude::rust_2021::*;
 
-#[cfg(not(test))] // See #65860
 #[macro_use]
 mod macros;
 
-// We don't export this through #[macro_export] for now, to avoid breakage.
-// See https://github.com/rust-lang/rust/issues/82913
-#[cfg(not(test))]
 #[unstable(feature = "assert_matches", issue = "82775")]
 /// Unstable module containing the unstable `assert_matches` macro.
 pub mod assert_matches {
diff --git a/library/core/src/macros/mod.rs b/library/core/src/macros/mod.rs
index 16200184422b9..12ec07a22c695 100644
--- a/library/core/src/macros/mod.rs
+++ b/library/core/src/macros/mod.rs
@@ -37,7 +37,7 @@ macro_rules! panic {
 /// ```
 #[macro_export]
 #[stable(feature = "rust1", since = "1.0.0")]
-#[cfg_attr(not(test), rustc_diagnostic_item = "assert_eq_macro")]
+#[rustc_diagnostic_item = "assert_eq_macro"]
 #[allow_internal_unstable(panic_internals)]
 macro_rules! assert_eq {
     ($left:expr, $right:expr $(,)?) => {
@@ -93,7 +93,7 @@ macro_rules! assert_eq {
 /// ```
 #[macro_export]
 #[stable(feature = "assert_ne", since = "1.13.0")]
-#[cfg_attr(not(test), rustc_diagnostic_item = "assert_ne_macro")]
+#[rustc_diagnostic_item = "assert_ne_macro"]
 #[allow_internal_unstable(panic_internals)]
 macro_rules! assert_ne {
     ($left:expr, $right:expr $(,)?) => {
@@ -331,7 +331,7 @@ macro_rules! debug_assert {
 /// ```
 #[macro_export]
 #[stable(feature = "rust1", since = "1.0.0")]
-#[cfg_attr(not(test), rustc_diagnostic_item = "debug_assert_eq_macro")]
+#[rustc_diagnostic_item = "debug_assert_eq_macro"]
 macro_rules! debug_assert_eq {
     ($($arg:tt)*) => {
         if $crate::cfg!(debug_assertions) {
@@ -361,7 +361,7 @@ macro_rules! debug_assert_eq {
 /// ```
 #[macro_export]
 #[stable(feature = "assert_ne", since = "1.13.0")]
-#[cfg_attr(not(test), rustc_diagnostic_item = "debug_assert_ne_macro")]
+#[rustc_diagnostic_item = "debug_assert_ne_macro"]
 macro_rules! debug_assert_ne {
     ($($arg:tt)*) => {
         if $crate::cfg!(debug_assertions) {
@@ -442,7 +442,7 @@ pub macro debug_assert_matches($($arg:tt)*) {
 /// ```
 #[macro_export]
 #[stable(feature = "matches_macro", since = "1.42.0")]
-#[cfg_attr(not(test), rustc_diagnostic_item = "matches_macro")]
+#[rustc_diagnostic_item = "matches_macro"]
 macro_rules! matches {
     ($expression:expr, $pattern:pat $(if $guard:expr)? $(,)?) => {
         match $expression {
@@ -617,7 +617,7 @@ macro_rules! r#try {
 /// ```
 #[macro_export]
 #[stable(feature = "rust1", since = "1.0.0")]
-#[cfg_attr(not(test), rustc_diagnostic_item = "write_macro")]
+#[rustc_diagnostic_item = "write_macro"]
 macro_rules! write {
     ($dst:expr, $($arg:tt)*) => {
         $dst.write_fmt($crate::format_args!($($arg)*))
@@ -651,7 +651,7 @@ macro_rules! write {
 /// ```
 #[macro_export]
 #[stable(feature = "rust1", since = "1.0.0")]
-#[cfg_attr(not(test), rustc_diagnostic_item = "writeln_macro")]
+#[rustc_diagnostic_item = "writeln_macro"]
 #[allow_internal_unstable(format_args_nl)]
 macro_rules! writeln {
     ($dst:expr $(,)?) => {
@@ -718,7 +718,7 @@ macro_rules! writeln {
 #[rustc_builtin_macro(unreachable)]
 #[allow_internal_unstable(edition_panic)]
 #[stable(feature = "rust1", since = "1.0.0")]
-#[cfg_attr(not(test), rustc_diagnostic_item = "unreachable_macro")]
+#[rustc_diagnostic_item = "unreachable_macro"]
 macro_rules! unreachable {
     // Expands to either `$crate::panic::unreachable_2015` or `$crate::panic::unreachable_2021`
     // depending on the edition of the caller.
@@ -803,7 +803,7 @@ macro_rules! unreachable {
 /// ```
 #[macro_export]
 #[stable(feature = "rust1", since = "1.0.0")]
-#[cfg_attr(not(test), rustc_diagnostic_item = "unimplemented_macro")]
+#[rustc_diagnostic_item = "unimplemented_macro"]
 #[allow_internal_unstable(panic_internals)]
 macro_rules! unimplemented {
     () => {
@@ -883,7 +883,7 @@ macro_rules! unimplemented {
 /// ```
 #[macro_export]
 #[stable(feature = "todo_macro", since = "1.40.0")]
-#[cfg_attr(not(test), rustc_diagnostic_item = "todo_macro")]
+#[rustc_diagnostic_item = "todo_macro"]
 #[allow_internal_unstable(panic_internals)]
 macro_rules! todo {
     () => {
@@ -995,7 +995,7 @@ pub(crate) mod builtin {
     /// and cannot be stored for later use.
     /// This is a known limitation, see [#92698](https://github.com/rust-lang/rust/issues/92698).
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[cfg_attr(not(test), rustc_diagnostic_item = "format_args_macro")]
+    #[rustc_diagnostic_item = "format_args_macro"]
     #[allow_internal_unsafe]
     #[allow_internal_unstable(fmt_internals)]
     #[rustc_builtin_macro]
@@ -1342,7 +1342,7 @@ pub(crate) mod builtin {
     #[stable(feature = "rust1", since = "1.0.0")]
     #[rustc_builtin_macro]
     #[macro_export]
-    #[cfg_attr(not(test), rustc_diagnostic_item = "include_str_macro")]
+    #[rustc_diagnostic_item = "include_str_macro"]
     macro_rules! include_str {
         ($file:expr $(,)?) => {{ /* compiler built-in */ }};
     }
@@ -1382,7 +1382,7 @@ pub(crate) mod builtin {
     #[stable(feature = "rust1", since = "1.0.0")]
     #[rustc_builtin_macro]
     #[macro_export]
-    #[cfg_attr(not(test), rustc_diagnostic_item = "include_bytes_macro")]
+    #[rustc_diagnostic_item = "include_bytes_macro"]
     macro_rules! include_bytes {
         ($file:expr $(,)?) => {{ /* compiler built-in */ }};
     }
diff --git a/library/core/src/marker.rs b/library/core/src/marker.rs
index b0571bf7247af..10c3c14afa890 100644
--- a/library/core/src/marker.rs
+++ b/library/core/src/marker.rs
@@ -82,7 +82,7 @@ macro marker_impls {
 /// [arc]: ../../std/sync/struct.Arc.html
 /// [ub]: ../../reference/behavior-considered-undefined.html
 #[stable(feature = "rust1", since = "1.0.0")]
-#[cfg_attr(not(test), rustc_diagnostic_item = "Send")]
+#[rustc_diagnostic_item = "Send"]
 #[diagnostic::on_unimplemented(
     message = "`{Self}` cannot be sent between threads safely",
     label = "`{Self}` cannot be sent between threads safely"
@@ -541,7 +541,7 @@ pub trait BikeshedGuaranteedNoDrop {}
 /// [transmute]: crate::mem::transmute
 /// [nomicon-send-and-sync]: ../../nomicon/send-and-sync.html
 #[stable(feature = "rust1", since = "1.0.0")]
-#[cfg_attr(not(test), rustc_diagnostic_item = "Sync")]
+#[rustc_diagnostic_item = "Sync"]
 #[lang = "sync"]
 #[rustc_on_unimplemented(
     on(
@@ -1302,7 +1302,7 @@ pub trait FnPtr: Copy + Clone {
 /// ```
 #[rustc_builtin_macro(CoercePointee, attributes(pointee))]
 #[allow_internal_unstable(dispatch_from_dyn, coerce_unsized, unsize, coerce_pointee_validated)]
-#[cfg_attr(not(test), rustc_diagnostic_item = "CoercePointee")]
+#[rustc_diagnostic_item = "CoercePointee"]
 #[unstable(feature = "derive_coerce_pointee", issue = "123430")]
 pub macro CoercePointee($item:item) {
     /* compiler built-in */
diff --git a/library/core/src/mem/mod.rs b/library/core/src/mem/mod.rs
index b9bb6d6a13f7f..fecab730a74c0 100644
--- a/library/core/src/mem/mod.rs
+++ b/library/core/src/mem/mod.rs
@@ -140,7 +140,7 @@ pub use crate::intrinsics::transmute;
 #[inline]
 #[rustc_const_stable(feature = "const_forget", since = "1.46.0")]
 #[stable(feature = "rust1", since = "1.0.0")]
-#[cfg_attr(not(test), rustc_diagnostic_item = "mem_forget")]
+#[rustc_diagnostic_item = "mem_forget"]
 pub const fn forget<T>(t: T) {
     let _ = ManuallyDrop::new(t);
 }
@@ -304,7 +304,7 @@ pub fn forget_unsized<T: ?Sized>(t: T) {
 #[stable(feature = "rust1", since = "1.0.0")]
 #[rustc_promotable]
 #[rustc_const_stable(feature = "const_mem_size_of", since = "1.24.0")]
-#[cfg_attr(not(test), rustc_diagnostic_item = "mem_size_of")]
+#[rustc_diagnostic_item = "mem_size_of"]
 pub const fn size_of<T>() -> usize {
     intrinsics::size_of::<T>()
 }
@@ -334,7 +334,7 @@ pub const fn size_of<T>() -> usize {
 #[must_use]
 #[stable(feature = "rust1", since = "1.0.0")]
 #[rustc_const_stable(feature = "const_size_of_val", since = "1.85.0")]
-#[cfg_attr(not(test), rustc_diagnostic_item = "mem_size_of_val")]
+#[rustc_diagnostic_item = "mem_size_of_val"]
 pub const fn size_of_val<T: ?Sized>(val: &T) -> usize {
     // SAFETY: `val` is a reference, so it's a valid raw pointer
     unsafe { intrinsics::size_of_val(val) }
@@ -856,7 +856,7 @@ pub fn take<T: Default>(dest: &mut T) -> T {
 #[stable(feature = "rust1", since = "1.0.0")]
 #[must_use = "if you don't need the old value, you can just assign the new value directly"]
 #[rustc_const_stable(feature = "const_replace", since = "1.83.0")]
-#[cfg_attr(not(test), rustc_diagnostic_item = "mem_replace")]
+#[rustc_diagnostic_item = "mem_replace"]
 pub const fn replace<T>(dest: &mut T, src: T) -> T {
     // It may be tempting to use `swap` to avoid `unsafe` here. Don't!
     // The compiler optimizes the implementation below to two `memcpy`s
@@ -936,7 +936,7 @@ pub const fn replace<T>(dest: &mut T, src: T) -> T {
 /// [`RefCell`]: crate::cell::RefCell
 #[inline]
 #[stable(feature = "rust1", since = "1.0.0")]
-#[cfg_attr(not(test), rustc_diagnostic_item = "mem_drop")]
+#[rustc_diagnostic_item = "mem_drop"]
 pub fn drop<T>(_x: T) {}
 
 /// Bitwise-copies a value.
@@ -1159,7 +1159,7 @@ impl<T> fmt::Debug for Discriminant<T> {
 /// ```
 #[stable(feature = "discriminant_value", since = "1.21.0")]
 #[rustc_const_stable(feature = "const_discriminant", since = "1.75.0")]
-#[cfg_attr(not(test), rustc_diagnostic_item = "mem_discriminant")]
+#[rustc_diagnostic_item = "mem_discriminant"]
 #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
 pub const fn discriminant<T>(v: &T) -> Discriminant<T> {
     Discriminant(intrinsics::discriminant_value(v))
diff --git a/library/core/src/net/ip_addr.rs b/library/core/src/net/ip_addr.rs
index 8e4417ec461b8..7aa5ed60d0467 100644
--- a/library/core/src/net/ip_addr.rs
+++ b/library/core/src/net/ip_addr.rs
@@ -25,7 +25,7 @@ use crate::ops::{BitAnd, BitAndAssign, BitOr, BitOrAssign, Not};
 /// assert_eq!(localhost_v4.is_ipv6(), false);
 /// assert_eq!(localhost_v4.is_ipv4(), true);
 /// ```
-#[cfg_attr(not(test), rustc_diagnostic_item = "IpAddr")]
+#[rustc_diagnostic_item = "IpAddr"]
 #[stable(feature = "ip_addr", since = "1.7.0")]
 #[derive(Copy, Clone, Eq, PartialEq, Hash, PartialOrd, Ord)]
 pub enum IpAddr {
diff --git a/library/core/src/num/f128.rs b/library/core/src/num/f128.rs
index 5e45974b3d422..b17190971c3e8 100644
--- a/library/core/src/num/f128.rs
+++ b/library/core/src/num/f128.rs
@@ -12,11 +12,9 @@
 #![unstable(feature = "f128", issue = "116909")]
 
 use crate::convert::FloatToInt;
-#[cfg(not(test))]
-use crate::intrinsics;
-use crate::mem;
 use crate::num::FpCategory;
 use crate::panic::const_assert;
+use crate::{intrinsics, mem};
 
 /// Basic mathematical constants.
 #[unstable(feature = "f128", issue = "116909")]
@@ -138,7 +136,6 @@ pub mod consts {
     pub const LN_10: f128 = 2.30258509299404568401799145468436420760110148862877297603333_f128;
 }
 
-#[cfg(not(test))]
 impl f128 {
     // FIXME(f16_f128): almost all methods in this `impl` are missing examples and a const
     // implementation. Add these once we can run code on all platforms and have f16/f128 in CTFE.
diff --git a/library/core/src/num/f16.rs b/library/core/src/num/f16.rs
index e3176cd168852..d20677f43b417 100644
--- a/library/core/src/num/f16.rs
+++ b/library/core/src/num/f16.rs
@@ -12,11 +12,9 @@
 #![unstable(feature = "f16", issue = "116909")]
 
 use crate::convert::FloatToInt;
-#[cfg(not(test))]
-use crate::intrinsics;
-use crate::mem;
 use crate::num::FpCategory;
 use crate::panic::const_assert;
+use crate::{intrinsics, mem};
 
 /// Basic mathematical constants.
 #[unstable(feature = "f16", issue = "116909")]
@@ -133,7 +131,6 @@ pub mod consts {
     pub const LN_10: f16 = 2.30258509299404568401799145468436421_f16;
 }
 
-#[cfg(not(test))]
 impl f16 {
     // FIXME(f16_f128): almost all methods in this `impl` are missing examples and a const
     // implementation. Add these once we can run code on all platforms and have f16/f128 in CTFE.
diff --git a/library/core/src/num/f32.rs b/library/core/src/num/f32.rs
index de1557ccc9028..79d864e1b1966 100644
--- a/library/core/src/num/f32.rs
+++ b/library/core/src/num/f32.rs
@@ -12,11 +12,9 @@
 #![stable(feature = "rust1", since = "1.0.0")]
 
 use crate::convert::FloatToInt;
-#[cfg(not(test))]
-use crate::intrinsics;
-use crate::mem;
 use crate::num::FpCategory;
 use crate::panic::const_assert;
+use crate::{intrinsics, mem};
 
 /// The radix or base of the internal representation of `f32`.
 /// Use [`f32::RADIX`] instead.
@@ -386,7 +384,6 @@ pub mod consts {
     pub const LN_10: f32 = 2.30258509299404568401799145468436421_f32;
 }
 
-#[cfg(not(test))]
 impl f32 {
     /// The radix or base of the internal representation of `f32`.
     #[stable(feature = "assoc_int_consts", since = "1.43.0")]
@@ -416,7 +413,7 @@ impl f32 {
     /// [Machine epsilon]: https://en.wikipedia.org/wiki/Machine_epsilon
     /// [`MANTISSA_DIGITS`]: f32::MANTISSA_DIGITS
     #[stable(feature = "assoc_int_consts", since = "1.43.0")]
-    #[cfg_attr(not(test), rustc_diagnostic_item = "f32_epsilon")]
+    #[rustc_diagnostic_item = "f32_epsilon"]
     pub const EPSILON: f32 = 1.19209290e-07_f32;
 
     /// Smallest finite `f32` value.
diff --git a/library/core/src/num/f64.rs b/library/core/src/num/f64.rs
index 65b5f3b9af093..ca28b40bb3adc 100644
--- a/library/core/src/num/f64.rs
+++ b/library/core/src/num/f64.rs
@@ -12,11 +12,9 @@
 #![stable(feature = "rust1", since = "1.0.0")]
 
 use crate::convert::FloatToInt;
-#[cfg(not(test))]
-use crate::intrinsics;
-use crate::mem;
 use crate::num::FpCategory;
 use crate::panic::const_assert;
+use crate::{intrinsics, mem};
 
 /// The radix or base of the internal representation of `f64`.
 /// Use [`f64::RADIX`] instead.
@@ -386,7 +384,6 @@ pub mod consts {
     pub const LN_10: f64 = 2.30258509299404568401799145468436421_f64;
 }
 
-#[cfg(not(test))]
 impl f64 {
     /// The radix or base of the internal representation of `f64`.
     #[stable(feature = "assoc_int_consts", since = "1.43.0")]
@@ -415,7 +412,7 @@ impl f64 {
     /// [Machine epsilon]: https://en.wikipedia.org/wiki/Machine_epsilon
     /// [`MANTISSA_DIGITS`]: f64::MANTISSA_DIGITS
     #[stable(feature = "assoc_int_consts", since = "1.43.0")]
-    #[cfg_attr(not(test), rustc_diagnostic_item = "f64_epsilon")]
+    #[rustc_diagnostic_item = "f64_epsilon"]
     pub const EPSILON: f64 = 2.2204460492503131e-16_f64;
 
     /// Smallest finite `f64` value.
diff --git a/library/core/src/ops/control_flow.rs b/library/core/src/ops/control_flow.rs
index 8993e14fcd379..0d910685927e0 100644
--- a/library/core/src/ops/control_flow.rs
+++ b/library/core/src/ops/control_flow.rs
@@ -79,7 +79,7 @@ use crate::{convert, ops};
 /// [`Break`]: ControlFlow::Break
 /// [`Continue`]: ControlFlow::Continue
 #[stable(feature = "control_flow_enum_type", since = "1.55.0")]
-#[cfg_attr(not(test), rustc_diagnostic_item = "ControlFlow")]
+#[rustc_diagnostic_item = "ControlFlow"]
 // ControlFlow should not implement PartialOrd or Ord, per RFC 3058:
 // https://rust-lang.github.io/rfcs/3058-try-trait-v2.html#traits-for-controlflow
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
diff --git a/library/core/src/option.rs b/library/core/src/option.rs
index a9f06b92ad5dd..75819fa6ce975 100644
--- a/library/core/src/option.rs
+++ b/library/core/src/option.rs
@@ -924,7 +924,7 @@ impl<T> Option<T> {
     #[inline]
     #[track_caller]
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[cfg_attr(not(test), rustc_diagnostic_item = "option_expect")]
+    #[rustc_diagnostic_item = "option_expect"]
     #[rustc_allow_const_fn_unstable(const_precise_live_drops)]
     #[rustc_const_stable(feature = "const_option", since = "1.83.0")]
     pub const fn expect(self, msg: &str) -> T {
@@ -969,7 +969,7 @@ impl<T> Option<T> {
     #[inline(always)]
     #[track_caller]
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[cfg_attr(not(test), rustc_diagnostic_item = "option_unwrap")]
+    #[rustc_diagnostic_item = "option_unwrap"]
     #[rustc_allow_const_fn_unstable(const_precise_live_drops)]
     #[rustc_const_stable(feature = "const_option", since = "1.83.0")]
     pub const fn unwrap(self) -> T {
diff --git a/library/core/src/panic/unwind_safe.rs b/library/core/src/panic/unwind_safe.rs
index 37859212c0ee3..a60f0799c0eae 100644
--- a/library/core/src/panic/unwind_safe.rs
+++ b/library/core/src/panic/unwind_safe.rs
@@ -82,7 +82,7 @@ use crate::task::{Context, Poll};
 /// [`AssertUnwindSafe`] wrapper struct can be used to force this trait to be
 /// implemented for any closed over variables passed to `catch_unwind`.
 #[stable(feature = "catch_unwind", since = "1.9.0")]
-#[cfg_attr(not(test), rustc_diagnostic_item = "unwind_safe_trait")]
+#[rustc_diagnostic_item = "unwind_safe_trait"]
 #[diagnostic::on_unimplemented(
     message = "the type `{Self}` may not be safely transferred across an unwind boundary",
     label = "`{Self}` may not be safely transferred across an unwind boundary"
@@ -98,7 +98,7 @@ pub auto trait UnwindSafe {}
 /// This is a "helper marker trait" used to provide impl blocks for the
 /// [`UnwindSafe`] trait, for more information see that documentation.
 #[stable(feature = "catch_unwind", since = "1.9.0")]
-#[cfg_attr(not(test), rustc_diagnostic_item = "ref_unwind_safe_trait")]
+#[rustc_diagnostic_item = "ref_unwind_safe_trait"]
 #[diagnostic::on_unimplemented(
     message = "the type `{Self}` may contain interior mutability and a reference may not be safely \
                transferrable across a catch_unwind boundary",
diff --git a/library/core/src/result.rs b/library/core/src/result.rs
index 92b5cba153166..2506e7be765b8 100644
--- a/library/core/src/result.rs
+++ b/library/core/src/result.rs
@@ -654,7 +654,7 @@ impl<T, E> Result<T, E> {
     /// ```
     #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[cfg_attr(not(test), rustc_diagnostic_item = "result_ok_method")]
+    #[rustc_diagnostic_item = "result_ok_method"]
     pub fn ok(self) -> Option<T> {
         match self {
             Ok(x) => Some(x),
diff --git a/library/core/src/slice/ascii.rs b/library/core/src/slice/ascii.rs
index 51b25fa40e3d9..91befdb8c78d9 100644
--- a/library/core/src/slice/ascii.rs
+++ b/library/core/src/slice/ascii.rs
@@ -7,7 +7,6 @@ use crate::fmt::{self, Write};
 use crate::intrinsics::const_eval_select;
 use crate::{ascii, iter, ops};
 
-#[cfg(not(test))]
 impl [u8] {
     /// Checks if all bytes in this slice are within the ASCII range.
     #[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
diff --git a/library/core/src/slice/mod.rs b/library/core/src/slice/mod.rs
index f991cc4ae2dbb..f66801d7424d8 100644
--- a/library/core/src/slice/mod.rs
+++ b/library/core/src/slice/mod.rs
@@ -97,7 +97,6 @@ enum Direction {
     Back,
 }
 
-#[cfg(not(test))]
 impl<T> [T] {
     /// Returns the number of elements in the slice.
     ///
@@ -1045,7 +1044,7 @@ impl<T> [T] {
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
-    #[cfg_attr(not(test), rustc_diagnostic_item = "slice_iter")]
+    #[rustc_diagnostic_item = "slice_iter"]
     pub fn iter(&self) -> Iter<'_, T> {
         Iter::new(self)
     }
@@ -4845,7 +4844,6 @@ impl<T, const N: usize> [[T; N]] {
     }
 }
 
-#[cfg(not(test))]
 impl [f32] {
     /// Sorts the slice of floats.
     ///
@@ -4874,7 +4872,6 @@ impl [f32] {
     }
 }
 
-#[cfg(not(test))]
 impl [f64] {
     /// Sorts the slice of floats.
     ///
diff --git a/library/core/src/str/mod.rs b/library/core/src/str/mod.rs
index 83ad10db2da45..5cc08f8a71afb 100644
--- a/library/core/src/str/mod.rs
+++ b/library/core/src/str/mod.rs
@@ -114,7 +114,6 @@ fn slice_error_fail_rt(s: &str, begin: usize, end: usize) -> ! {
     );
 }
 
-#[cfg(not(test))]
 impl str {
     /// Returns the length of `self`.
     ///
@@ -134,7 +133,7 @@ impl str {
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     #[rustc_const_stable(feature = "const_str_len", since = "1.39.0")]
-    #[cfg_attr(not(test), rustc_diagnostic_item = "str_len")]
+    #[rustc_diagnostic_item = "str_len"]
     #[must_use]
     #[inline]
     pub const fn len(&self) -> usize {
@@ -1029,7 +1028,7 @@ impl str {
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
-    #[cfg_attr(not(test), rustc_diagnostic_item = "str_chars")]
+    #[rustc_diagnostic_item = "str_chars"]
     pub fn chars(&self) -> Chars<'_> {
         Chars { iter: self.as_bytes().iter() }
     }
@@ -1160,7 +1159,7 @@ impl str {
     #[must_use = "this returns the split string as an iterator, \
                   without modifying the original"]
     #[stable(feature = "split_whitespace", since = "1.1.0")]
-    #[cfg_attr(not(test), rustc_diagnostic_item = "str_split_whitespace")]
+    #[rustc_diagnostic_item = "str_split_whitespace"]
     #[inline]
     pub fn split_whitespace(&self) -> SplitWhitespace<'_> {
         SplitWhitespace { inner: self.split(IsWhitespace).filter(IsNotEmpty) }
@@ -1355,7 +1354,7 @@ impl str {
     /// assert!(bananas.starts_with(&['a', 'b', 'c', 'd']));
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[cfg_attr(not(test), rustc_diagnostic_item = "str_starts_with")]
+    #[rustc_diagnostic_item = "str_starts_with"]
     pub fn starts_with<P: Pattern>(&self, pat: P) -> bool {
         pat.is_prefix_of(self)
     }
@@ -1380,7 +1379,7 @@ impl str {
     /// assert!(!bananas.ends_with("nana"));
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[cfg_attr(not(test), rustc_diagnostic_item = "str_ends_with")]
+    #[rustc_diagnostic_item = "str_ends_with"]
     pub fn ends_with<P: Pattern>(&self, pat: P) -> bool
     where
         for<'a> P::Searcher<'a>: ReverseSearcher<'a>,
@@ -2114,7 +2113,7 @@ impl str {
     #[must_use = "this returns the trimmed string as a slice, \
                   without modifying the original"]
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[cfg_attr(not(test), rustc_diagnostic_item = "str_trim")]
+    #[rustc_diagnostic_item = "str_trim"]
     pub fn trim(&self) -> &str {
         self.trim_matches(|c: char| c.is_whitespace())
     }
@@ -2153,7 +2152,7 @@ impl str {
     #[must_use = "this returns the trimmed string as a new slice, \
                   without modifying the original"]
     #[stable(feature = "trim_direction", since = "1.30.0")]
-    #[cfg_attr(not(test), rustc_diagnostic_item = "str_trim_start")]
+    #[rustc_diagnostic_item = "str_trim_start"]
     pub fn trim_start(&self) -> &str {
         self.trim_start_matches(|c: char| c.is_whitespace())
     }
@@ -2192,7 +2191,7 @@ impl str {
     #[must_use = "this returns the trimmed string as a new slice, \
                   without modifying the original"]
     #[stable(feature = "trim_direction", since = "1.30.0")]
-    #[cfg_attr(not(test), rustc_diagnostic_item = "str_trim_end")]
+    #[rustc_diagnostic_item = "str_trim_end"]
     pub fn trim_end(&self) -> &str {
         self.trim_end_matches(|c: char| c.is_whitespace())
     }
diff --git a/library/core/src/sync/atomic.rs b/library/core/src/sync/atomic.rs
index 73180bde54aa9..bf2b6d59f8824 100644
--- a/library/core/src/sync/atomic.rs
+++ b/library/core/src/sync/atomic.rs
@@ -294,7 +294,7 @@ unsafe impl Sync for AtomicBool {}
 /// loads and stores of pointers. Its size depends on the target pointer's size.
 #[cfg(target_has_atomic_load_store = "ptr")]
 #[stable(feature = "rust1", since = "1.0.0")]
-#[cfg_attr(not(test), rustc_diagnostic_item = "AtomicPtr")]
+#[rustc_diagnostic_item = "AtomicPtr"]
 #[cfg_attr(target_pointer_width = "16", repr(C, align(2)))]
 #[cfg_attr(target_pointer_width = "32", repr(C, align(4)))]
 #[cfg_attr(target_pointer_width = "64", repr(C, align(8)))]
@@ -3445,7 +3445,7 @@ atomic_int! {
     stable(feature = "integer_atomics_stable", since = "1.34.0"),
     rustc_const_stable(feature = "const_integer_atomics", since = "1.34.0"),
     rustc_const_stable(feature = "const_atomic_into_inner", since = "1.79.0"),
-    cfg_attr(not(test), rustc_diagnostic_item = "AtomicI8"),
+    rustc_diagnostic_item = "AtomicI8",
     "i8",
     "",
     atomic_min, atomic_max,
@@ -3464,7 +3464,7 @@ atomic_int! {
     stable(feature = "integer_atomics_stable", since = "1.34.0"),
     rustc_const_stable(feature = "const_integer_atomics", since = "1.34.0"),
     rustc_const_stable(feature = "const_atomic_into_inner", since = "1.79.0"),
-    cfg_attr(not(test), rustc_diagnostic_item = "AtomicU8"),
+    rustc_diagnostic_item = "AtomicU8",
     "u8",
     "",
     atomic_umin, atomic_umax,
@@ -3483,7 +3483,7 @@ atomic_int! {
     stable(feature = "integer_atomics_stable", since = "1.34.0"),
     rustc_const_stable(feature = "const_integer_atomics", since = "1.34.0"),
     rustc_const_stable(feature = "const_atomic_into_inner", since = "1.79.0"),
-    cfg_attr(not(test), rustc_diagnostic_item = "AtomicI16"),
+    rustc_diagnostic_item = "AtomicI16",
     "i16",
     "",
     atomic_min, atomic_max,
@@ -3502,7 +3502,7 @@ atomic_int! {
     stable(feature = "integer_atomics_stable", since = "1.34.0"),
     rustc_const_stable(feature = "const_integer_atomics", since = "1.34.0"),
     rustc_const_stable(feature = "const_atomic_into_inner", since = "1.79.0"),
-    cfg_attr(not(test), rustc_diagnostic_item = "AtomicU16"),
+    rustc_diagnostic_item = "AtomicU16",
     "u16",
     "",
     atomic_umin, atomic_umax,
@@ -3521,7 +3521,7 @@ atomic_int! {
     stable(feature = "integer_atomics_stable", since = "1.34.0"),
     rustc_const_stable(feature = "const_integer_atomics", since = "1.34.0"),
     rustc_const_stable(feature = "const_atomic_into_inner", since = "1.79.0"),
-    cfg_attr(not(test), rustc_diagnostic_item = "AtomicI32"),
+    rustc_diagnostic_item = "AtomicI32",
     "i32",
     "",
     atomic_min, atomic_max,
@@ -3540,7 +3540,7 @@ atomic_int! {
     stable(feature = "integer_atomics_stable", since = "1.34.0"),
     rustc_const_stable(feature = "const_integer_atomics", since = "1.34.0"),
     rustc_const_stable(feature = "const_atomic_into_inner", since = "1.79.0"),
-    cfg_attr(not(test), rustc_diagnostic_item = "AtomicU32"),
+    rustc_diagnostic_item = "AtomicU32",
     "u32",
     "",
     atomic_umin, atomic_umax,
@@ -3559,7 +3559,7 @@ atomic_int! {
     stable(feature = "integer_atomics_stable", since = "1.34.0"),
     rustc_const_stable(feature = "const_integer_atomics", since = "1.34.0"),
     rustc_const_stable(feature = "const_atomic_into_inner", since = "1.79.0"),
-    cfg_attr(not(test), rustc_diagnostic_item = "AtomicI64"),
+    rustc_diagnostic_item = "AtomicI64",
     "i64",
     "",
     atomic_min, atomic_max,
@@ -3578,7 +3578,7 @@ atomic_int! {
     stable(feature = "integer_atomics_stable", since = "1.34.0"),
     rustc_const_stable(feature = "const_integer_atomics", since = "1.34.0"),
     rustc_const_stable(feature = "const_atomic_into_inner", since = "1.79.0"),
-    cfg_attr(not(test), rustc_diagnostic_item = "AtomicU64"),
+    rustc_diagnostic_item = "AtomicU64",
     "u64",
     "",
     atomic_umin, atomic_umax,
@@ -3597,7 +3597,7 @@ atomic_int! {
     unstable(feature = "integer_atomics", issue = "99069"),
     rustc_const_unstable(feature = "integer_atomics", issue = "99069"),
     rustc_const_unstable(feature = "integer_atomics", issue = "99069"),
-    cfg_attr(not(test), rustc_diagnostic_item = "AtomicI128"),
+    rustc_diagnostic_item = "AtomicI128",
     "i128",
     "#![feature(integer_atomics)]\n\n",
     atomic_min, atomic_max,
@@ -3616,7 +3616,7 @@ atomic_int! {
     unstable(feature = "integer_atomics", issue = "99069"),
     rustc_const_unstable(feature = "integer_atomics", issue = "99069"),
     rustc_const_unstable(feature = "integer_atomics", issue = "99069"),
-    cfg_attr(not(test), rustc_diagnostic_item = "AtomicU128"),
+    rustc_diagnostic_item = "AtomicU128",
     "u128",
     "#![feature(integer_atomics)]\n\n",
     atomic_umin, atomic_umax,
@@ -3639,7 +3639,7 @@ macro_rules! atomic_int_ptr_sized {
             stable(feature = "atomic_nand", since = "1.27.0"),
             rustc_const_stable(feature = "const_ptr_sized_atomics", since = "1.24.0"),
             rustc_const_stable(feature = "const_atomic_into_inner", since = "1.79.0"),
-            cfg_attr(not(test), rustc_diagnostic_item = "AtomicIsize"),
+            rustc_diagnostic_item = "AtomicIsize",
             "isize",
             "",
             atomic_min, atomic_max,
@@ -3658,7 +3658,7 @@ macro_rules! atomic_int_ptr_sized {
             stable(feature = "atomic_nand", since = "1.27.0"),
             rustc_const_stable(feature = "const_ptr_sized_atomics", since = "1.24.0"),
             rustc_const_stable(feature = "const_atomic_into_inner", since = "1.79.0"),
-            cfg_attr(not(test), rustc_diagnostic_item = "AtomicUsize"),
+            rustc_diagnostic_item = "AtomicUsize",
             "usize",
             "",
             atomic_umin, atomic_umax,
diff --git a/library/core/src/task/wake.rs b/library/core/src/task/wake.rs
index 3f57b04753a6b..9b8fefe42af60 100644
--- a/library/core/src/task/wake.rs
+++ b/library/core/src/task/wake.rs
@@ -402,7 +402,7 @@ impl<'a> ContextBuilder<'a> {
 /// [`Wake`]: ../../alloc/task/trait.Wake.html
 #[repr(transparent)]
 #[stable(feature = "futures_api", since = "1.36.0")]
-#[cfg_attr(not(test), rustc_diagnostic_item = "Waker")]
+#[rustc_diagnostic_item = "Waker"]
 pub struct Waker {
     waker: RawWaker,
 }
diff --git a/library/core/src/time.rs b/library/core/src/time.rs
index 8b211b442eab6..0064876f40112 100644
--- a/library/core/src/time.rs
+++ b/library/core/src/time.rs
@@ -77,7 +77,7 @@ const DAYS_PER_WEEK: u64 = 7;
 /// crate to do so.
 #[stable(feature = "duration", since = "1.3.0")]
 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Default)]
-#[cfg_attr(not(test), rustc_diagnostic_item = "Duration")]
+#[rustc_diagnostic_item = "Duration"]
 pub struct Duration {
     secs: u64,
     nanos: Nanoseconds, // Always 0 <= nanos < NANOS_PER_SEC