rust-lang · Voultapher · Jan 18, 2026 · RalfJung · Jan 19, 2026 · Voultapher
diff --git a/compiler/rustc_abi/src/lib.rs b/compiler/rustc_abi/src/lib.rs
@@ -1,6 +1,7 @@
 // tidy-alphabetical-start
+#![cfg_attr(all(feature = "nightly", bootstrap), feature(assert_matches))]
+#![cfg_attr(all(feature = "nightly", not(bootstrap)), feature(assert_matches_re_export))]
 #![cfg_attr(feature = "nightly", allow(internal_features))]
-#![cfg_attr(feature = "nightly", feature(assert_matches))]
 #![cfg_attr(feature = "nightly", feature(rustc_attrs))]
 #![cfg_attr(feature = "nightly", feature(step_trait))]
 // tidy-alphabetical-end

diff --git a/compiler/rustc_borrowck/src/lib.rs b/compiler/rustc_borrowck/src/lib.rs
@@ -2,7 +2,8 @@
 
 // tidy-alphabetical-start
 #![allow(internal_features)]
-#![feature(assert_matches)]
+#![cfg_attr(bootstrap, feature(assert_matches))]
+#![cfg_attr(not(bootstrap), feature(assert_matches_re_export))]
 #![feature(box_patterns)]
 #![feature(file_buffered)]
 #![feature(if_let_guard)]

diff --git a/compiler/rustc_builtin_macros/src/lib.rs b/compiler/rustc_builtin_macros/src/lib.rs
@@ -5,7 +5,8 @@
 #![allow(internal_features)]
 #![allow(rustc::diagnostic_outside_of_impl)]
 #![allow(rustc::untranslatable_diagnostic)]
-#![feature(assert_matches)]
+#![cfg_attr(bootstrap, feature(assert_matches))]
+#![cfg_attr(not(bootstrap), feature(assert_matches_re_export))]
 #![feature(box_patterns)]
 #![feature(decl_macro)]
 #![feature(if_let_guard)]

diff --git a/compiler/rustc_codegen_llvm/src/lib.rs b/compiler/rustc_codegen_llvm/src/lib.rs
@@ -5,7 +5,8 @@
 //! This API is completely unstable and subject to change.
 
 // tidy-alphabetical-start
-#![feature(assert_matches)]
+#![cfg_attr(bootstrap, feature(assert_matches))]
+#![cfg_attr(not(bootstrap), feature(assert_matches_re_export))]
 #![feature(extern_types)]
 #![feature(file_buffered)]
 #![feature(if_let_guard)]

diff --git a/compiler/rustc_codegen_ssa/src/lib.rs b/compiler/rustc_codegen_ssa/src/lib.rs
@@ -1,7 +1,8 @@
 // tidy-alphabetical-start
 #![allow(rustc::diagnostic_outside_of_impl)]
 #![allow(rustc::untranslatable_diagnostic)]
-#![feature(assert_matches)]
+#![cfg_attr(bootstrap, feature(assert_matches))]
+#![cfg_attr(not(bootstrap), feature(assert_matches_re_export))]
 #![feature(box_patterns)]
 #![feature(file_buffered)]
 #![feature(if_let_guard)]

diff --git a/compiler/rustc_const_eval/src/lib.rs b/compiler/rustc_const_eval/src/lib.rs
@@ -1,7 +1,8 @@
 // tidy-alphabetical-start
 #![allow(rustc::diagnostic_outside_of_impl)]
+#![cfg_attr(bootstrap, feature(assert_matches))]
+#![cfg_attr(not(bootstrap), feature(assert_matches_re_export))]
 #![feature(array_try_map)]
-#![feature(assert_matches)]
 #![feature(box_patterns)]
 #![feature(decl_macro)]
 #![feature(if_let_guard)]

diff --git a/compiler/rustc_data_structures/src/lib.rs b/compiler/rustc_data_structures/src/lib.rs
@@ -11,11 +11,12 @@
 #![allow(rustc::default_hash_types)]
 #![allow(rustc::potential_query_instability)]
 #![cfg_attr(bootstrap, feature(array_windows))]
+#![cfg_attr(bootstrap, feature(assert_matches))]
+#![cfg_attr(not(bootstrap), feature(assert_matches_re_export))]
 #![deny(unsafe_op_in_unsafe_fn)]
 #![feature(allocator_api)]
 #![feature(ascii_char)]
 #![feature(ascii_char_variants)]
-#![feature(assert_matches)]
 #![feature(auto_traits)]
 #![feature(cfg_select)]
 #![feature(const_default)]

diff --git a/compiler/rustc_errors/src/lib.rs b/compiler/rustc_errors/src/lib.rs
@@ -8,7 +8,8 @@
 #![allow(rustc::direct_use_of_rustc_type_ir)]
 #![allow(rustc::untranslatable_diagnostic)]
 #![cfg_attr(bootstrap, feature(array_windows))]
-#![feature(assert_matches)]
+#![cfg_attr(bootstrap, feature(assert_matches))]
+#![cfg_attr(not(bootstrap), feature(assert_matches_re_export))]
 #![feature(associated_type_defaults)]
 #![feature(box_patterns)]
 #![feature(default_field_values)]

diff --git a/compiler/rustc_hir_analysis/src/lib.rs b/compiler/rustc_hir_analysis/src/lib.rs
@@ -58,7 +58,8 @@ This API is completely unstable and subject to change.
 // tidy-alphabetical-start
 #![allow(rustc::diagnostic_outside_of_impl)]
 #![allow(rustc::untranslatable_diagnostic)]
-#![feature(assert_matches)]
+#![cfg_attr(bootstrap, feature(assert_matches))]
+#![cfg_attr(not(bootstrap), feature(assert_matches_re_export))]
 #![feature(gen_blocks)]
 #![feature(if_let_guard)]
 #![feature(iter_intersperse)]

diff --git a/compiler/rustc_hir_typeck/src/lib.rs b/compiler/rustc_hir_typeck/src/lib.rs
@@ -1,5 +1,6 @@
 // tidy-alphabetical-start
-#![feature(assert_matches)]
+#![cfg_attr(bootstrap, feature(assert_matches))]
+#![cfg_attr(not(bootstrap), feature(assert_matches_re_export))]
 #![feature(box_patterns)]
 #![feature(if_let_guard)]
 #![feature(iter_intersperse)]

diff --git a/compiler/rustc_infer/src/lib.rs b/compiler/rustc_infer/src/lib.rs
@@ -14,7 +14,8 @@
 
 // tidy-alphabetical-start
 #![allow(rustc::direct_use_of_rustc_type_ir)]
-#![feature(assert_matches)]
+#![cfg_attr(bootstrap, feature(assert_matches))]
+#![cfg_attr(not(bootstrap), feature(assert_matches_re_export))]
 #![feature(extend_one)]
 #![recursion_limit = "512"] // For rustdoc
 // tidy-alphabetical-end

diff --git a/compiler/rustc_lint/src/lib.rs b/compiler/rustc_lint/src/lib.rs
@@ -22,7 +22,8 @@
 // tidy-alphabetical-start
 #![allow(internal_features)]
 #![cfg_attr(bootstrap, feature(array_windows))]
-#![feature(assert_matches)]
+#![cfg_attr(bootstrap, feature(assert_matches))]
+#![cfg_attr(not(bootstrap), feature(assert_matches_re_export))]
 #![feature(box_patterns)]
 #![feature(if_let_guard)]
 #![feature(iter_order_by)]

diff --git a/compiler/rustc_middle/src/lib.rs b/compiler/rustc_middle/src/lib.rs
@@ -30,8 +30,9 @@
 #![allow(rustc::direct_use_of_rustc_type_ir)]
 #![allow(rustc::untranslatable_diagnostic)]
 #![cfg_attr(bootstrap, feature(array_windows))]
+#![cfg_attr(bootstrap, feature(assert_matches))]
+#![cfg_attr(not(bootstrap), feature(assert_matches_re_export))]
 #![feature(allocator_api)]
-#![feature(assert_matches)]
 #![feature(associated_type_defaults)]
 #![feature(box_as_ptr)]
 #![feature(box_patterns)]

diff --git a/compiler/rustc_mir_build/src/lib.rs b/compiler/rustc_mir_build/src/lib.rs
@@ -3,7 +3,8 @@
 // tidy-alphabetical-start
 #![allow(rustc::diagnostic_outside_of_impl)]
 #![allow(rustc::untranslatable_diagnostic)]
-#![feature(assert_matches)]
+#![cfg_attr(bootstrap, feature(assert_matches))]
+#![cfg_attr(not(bootstrap), feature(assert_matches_re_export))]
 #![feature(box_patterns)]
 #![feature(if_let_guard)]
 #![feature(try_blocks)]

diff --git a/compiler/rustc_mir_dataflow/src/lib.rs b/compiler/rustc_mir_dataflow/src/lib.rs
@@ -1,5 +1,6 @@
 // tidy-alphabetical-start
-#![feature(assert_matches)]
+#![cfg_attr(bootstrap, feature(assert_matches))]
+#![cfg_attr(not(bootstrap), feature(assert_matches_re_export))]
 #![feature(associated_type_defaults)]
 #![feature(box_patterns)]
 #![feature(exact_size_is_empty)]

diff --git a/compiler/rustc_mir_transform/src/lib.rs b/compiler/rustc_mir_transform/src/lib.rs
@@ -1,6 +1,7 @@
 // tidy-alphabetical-start
 #![cfg_attr(bootstrap, feature(array_windows))]
-#![feature(assert_matches)]
+#![cfg_attr(bootstrap, feature(assert_matches))]
+#![cfg_attr(not(bootstrap), feature(assert_matches_re_export))]
 #![feature(box_patterns)]
 #![feature(const_type_name)]
 #![feature(cow_is_borrowed)]

diff --git a/compiler/rustc_parse/src/lib.rs b/compiler/rustc_parse/src/lib.rs
@@ -3,7 +3,8 @@
 // tidy-alphabetical-start
 #![allow(rustc::diagnostic_outside_of_impl)]
 #![allow(rustc::untranslatable_diagnostic)]
-#![feature(assert_matches)]
+#![cfg_attr(bootstrap, feature(assert_matches))]
+#![cfg_attr(not(bootstrap), feature(assert_matches_re_export))]
 #![feature(box_patterns)]
 #![feature(debug_closure_helpers)]
 #![feature(default_field_values)]

diff --git a/compiler/rustc_query_system/src/lib.rs b/compiler/rustc_query_system/src/lib.rs
@@ -1,6 +1,7 @@
 // tidy-alphabetical-start
 #![allow(internal_features)]
-#![feature(assert_matches)]
+#![cfg_attr(bootstrap, feature(assert_matches))]
+#![cfg_attr(not(bootstrap), feature(assert_matches_re_export))]
 #![feature(core_intrinsics)]
 #![feature(min_specialization)]
 // tidy-alphabetical-end

diff --git a/compiler/rustc_resolve/src/lib.rs b/compiler/rustc_resolve/src/lib.rs
@@ -10,8 +10,9 @@
 #![allow(internal_features)]
 #![allow(rustc::diagnostic_outside_of_impl)]
 #![allow(rustc::untranslatable_diagnostic)]
+#![cfg_attr(bootstrap, feature(assert_matches))]
+#![cfg_attr(not(bootstrap), feature(assert_matches_re_export))]
 #![feature(arbitrary_self_types)]
-#![feature(assert_matches)]
 #![feature(box_patterns)]
 #![feature(const_default)]
 #![feature(const_trait_impl)]

diff --git a/compiler/rustc_symbol_mangling/src/lib.rs b/compiler/rustc_symbol_mangling/src/lib.rs
@@ -88,7 +88,8 @@
 //! DefPaths which are much more robust in the face of changes to the code base.
 
 // tidy-alphabetical-start
-#![feature(assert_matches)]
+#![cfg_attr(bootstrap, feature(assert_matches))]
+#![cfg_attr(not(bootstrap), feature(assert_matches_re_export))]
 // tidy-alphabetical-end
 
 use rustc_hir::def::DefKind;

diff --git a/compiler/rustc_trait_selection/src/lib.rs b/compiler/rustc_trait_selection/src/lib.rs
@@ -13,7 +13,8 @@
 // tidy-alphabetical-start
 #![allow(rustc::diagnostic_outside_of_impl)]
 #![allow(rustc::untranslatable_diagnostic)]
-#![feature(assert_matches)]
+#![cfg_attr(bootstrap, feature(assert_matches))]
+#![cfg_attr(not(bootstrap), feature(assert_matches_re_export))]
 #![feature(associated_type_defaults)]
 #![feature(box_patterns)]
 #![feature(default_field_values)]

diff --git a/compiler/rustc_ty_utils/src/lib.rs b/compiler/rustc_ty_utils/src/lib.rs
@@ -5,7 +5,8 @@
 //! This API is completely unstable and subject to change.
 
 // tidy-alphabetical-start
-#![feature(assert_matches)]
+#![cfg_attr(bootstrap, feature(assert_matches))]
+#![cfg_attr(not(bootstrap), feature(assert_matches_re_export))]
 #![feature(associated_type_defaults)]
 #![feature(box_patterns)]
 #![feature(if_let_guard)]

diff --git a/library/alloc/src/collections/btree/map/tests.rs b/library/alloc/src/collections/btree/map/tests.rs
@@ -1,4 +1,3 @@
-use core::assert_matches::assert_matches;
 use std::iter;
 use std::ops::Bound::{Excluded, Included, Unbounded};
 use std::panic::{AssertUnwindSafe, catch_unwind};
@@ -2578,14 +2577,14 @@ fn cursor_peek_prev_agrees_with_cursor_mut() {
     assert!(cursor.peek_next().is_none());
 
     let prev = cursor.peek_prev();
-    assert_matches!(prev, Some((&3, _)));
+    assert!(matches!(prev, Some((&3, _))));
 
     // Shadow names so the two parts of this test match.
     let mut cursor = map.lower_bound_mut(Bound::Excluded(&3));
     assert!(cursor.peek_next().is_none());
 
     let prev = cursor.peek_prev();
-    assert_matches!(prev, Some((&3, _)));
+    assert!(matches!(prev, Some((&3, _))));
 }
 
 #[test]

diff --git a/library/alloc/src/lib.rs b/library/alloc/src/lib.rs
@@ -89,7 +89,6 @@
 #![feature(allocator_api)]
 #![feature(array_into_iter_constructors)]
 #![feature(ascii_char)]
-#![feature(assert_matches)]
 #![feature(async_fn_traits)]
 #![feature(async_iterator)]
 #![feature(box_vec_non_null)]

diff --git a/library/alloctests/lib.rs b/library/alloctests/lib.rs
@@ -16,7 +16,6 @@
 // tidy-alphabetical-start
 #![feature(allocator_api)]
 #![feature(array_into_iter_constructors)]
-#![feature(assert_matches)]
 #![feature(box_vec_non_null)]
 #![feature(char_internals)]
 #![feature(const_alloc_error)]

diff --git a/library/alloctests/tests/c_str2.rs b/library/alloctests/tests/c_str2.rs
@@ -1,7 +1,7 @@
 use alloc::ffi::CString;
 use alloc::rc::Rc;
 use alloc::sync::Arc;
-use core::assert_matches::assert_matches;
+use core::assert_matches;
 use core::ffi::{CStr, FromBytesUntilNulError, c_char};
 #[allow(deprecated)]
 use core::hash::SipHasher13 as DefaultHasher;

diff --git a/library/alloctests/tests/lib.rs b/library/alloctests/tests/lib.rs
@@ -2,7 +2,6 @@
 #![feature(const_heap)]
 #![feature(deque_extend_front)]
 #![feature(iter_array_chunks)]
-#![feature(assert_matches)]
 #![feature(wtf8_internals)]
 #![feature(cow_is_borrowed)]
 #![feature(core_intrinsics)]

diff --git a/library/alloctests/tests/str.rs b/library/alloctests/tests/str.rs
@@ -1,6 +1,6 @@
 #![allow(invalid_from_utf8)]
 
-use std::assert_matches::assert_matches;
+use std::assert_matches;
 use std::borrow::Cow;
 use std::cmp::Ordering::{Equal, Greater, Less};
 use std::str::{from_utf8, from_utf8_unchecked};

diff --git a/library/alloctests/tests/string.rs b/library/alloctests/tests/string.rs
@@ -1,4 +1,4 @@
-use std::assert_matches::assert_matches;
+use std::assert_matches;
 use std::borrow::Cow;
 use std::cell::Cell;
 use std::collections::TryReserveErrorKind::*;

diff --git a/library/alloctests/tests/vec.rs b/library/alloctests/tests/vec.rs
@@ -3,7 +3,7 @@ use core::num::NonZero;
 use core::ptr::NonNull;
 use core::{assert_eq, assert_ne};
 use std::alloc::System;
-use std::assert_matches::assert_matches;
+use std::assert_matches;
 use std::borrow::Cow;
 use std::cell::Cell;
 use std::collections::TryReserveErrorKind::*;

diff --git a/library/alloctests/tests/vec_deque.rs b/library/alloctests/tests/vec_deque.rs
@@ -1,6 +1,6 @@
 use core::cell::Cell;
 use core::num::NonZero;
-use std::assert_matches::assert_matches;
+use std::assert_matches;
 use std::collections::TryReserveErrorKind::*;
 use std::collections::VecDeque;
 use std::collections::vec_deque::Drain;

diff --git a/library/core/src/lib.rs b/library/core/src/lib.rs
@@ -222,12 +222,12 @@ use prelude::rust_2024::*;
 #[macro_use]
 mod macros;
 
-#[unstable(feature = "assert_matches", issue = "82775")]
-/// Unstable module containing the unstable `assert_matches` macro.
-pub mod assert_matches {
-    #[unstable(feature = "assert_matches", issue = "82775")]
-    pub use crate::macros::{assert_matches, debug_assert_matches};
-}
+// These macros are explicitly exported here and not in the preludes - for now - to require manual
+// import by users to avoid compatibility issues such as with the third-party assert_matches macro.
+// See https://github.com/rust-lang/rust/pull/137487 and
+// https://github.com/rust-lang/rust/issues/82913
+#[stable(feature = "assert_matches", since = "CURRENT_RUSTC_VERSION")]
+pub use crate::macros::{assert_matches, debug_assert_matches};
 
 #[unstable(feature = "derive_from", issue = "144889")]
 /// Unstable module containing the unstable `From` derive macro.

diff --git a/library/core/src/macros/mod.rs b/library/core/src/macros/mod.rs
@@ -138,7 +138,7 @@ macro_rules! assert_ne {
 /// be disabled. See [`debug_assert_matches!`] for assertions that are disabled in
 /// release builds by default.
 ///
-/// [`debug_assert_matches!`]: crate::assert_matches::debug_assert_matches
+/// [`debug_assert_matches!`]: crate::debug_assert_matches
 ///
 /// On panic, this macro will print the value of the expression with its debug representation.
 ///
@@ -147,9 +147,7 @@ macro_rules! assert_ne {
 /// # Examples
 ///
 /// ```
-/// #![feature(assert_matches)]
-///
-/// use std::assert_matches::assert_matches;
+/// use std::assert_matches;
 ///
 /// let a = Some(345);
 /// let b = Some(56);
@@ -166,7 +164,7 @@ macro_rules! assert_ne {
 /// assert_matches!(a, Some(x) if x > 100);
 /// // assert_matches!(a, Some(x) if x < 100); // panics
 /// ```
-#[unstable(feature = "assert_matches", issue = "82775")]
+#[stable(feature = "assert_matches", since = "CURRENT_RUSTC_VERSION")]
 #[allow_internal_unstable(panic_internals)]
 #[rustc_macro_transparency = "semiopaque"]
 pub macro assert_matches {
@@ -380,9 +378,7 @@ macro_rules! debug_assert_ne {
 /// # Examples
 ///
 /// ```
-/// #![feature(assert_matches)]
-///
-/// use std::assert_matches::debug_assert_matches;
+/// use std::debug_assert_matches;
 ///
 /// let a = Some(345);
 /// let b = Some(56);
@@ -399,12 +395,12 @@ macro_rules! debug_assert_ne {
 /// debug_assert_matches!(a, Some(x) if x > 100);
 /// // debug_assert_matches!(a, Some(x) if x < 100); // panics
 /// ```
-#[unstable(feature = "assert_matches", issue = "82775")]
+#[stable(feature = "assert_matches", since = "CURRENT_RUSTC_VERSION")]
 #[allow_internal_unstable(assert_matches)]
 #[rustc_macro_transparency = "semiopaque"]
 pub macro debug_assert_matches($($arg:tt)*) {
     if $crate::cfg!(debug_assertions) {
-        $crate::assert_matches::assert_matches!($($arg)*);
+        $crate::assert_matches!($($arg)*);
     }
 }