rust-lang · rust-bors · Mar 25, 2026 · Mar 24, 2026 · Mar 24, 2026 · Mar 24, 2026
diff --git a/compiler/rustc_lint/src/early/diagnostics.rs b/compiler/rustc_lint/src/early/diagnostics.rs
@@ -153,9 +153,6 @@ impl<'a> Diagnostic<'a, ()> for DecorateBuiltinLint<'_, '_> {
                 .into_diag(dcx, level)
             }
 
-            BuiltinLintDiag::UnusedCrateDependency { extern_crate, local_crate } => {
-                lints::UnusedCrateDependency { extern_crate, local_crate }.into_diag(dcx, level)
-            }
             BuiltinLintDiag::AttributeLint(kind) => {
                 DecorateAttrLint { sess: self.sess, tcx: self.tcx, diagnostic: &kind }
                     .into_diag(dcx, level)

diff --git a/compiler/rustc_lint/src/lints.rs b/compiler/rustc_lint/src/lints.rs
@@ -2994,14 +2994,6 @@ pub(crate) mod unexpected_cfg_value {
     }
 }
 
-#[derive(Diagnostic)]
-#[diag("extern crate `{$extern_crate}` is unused in crate `{$local_crate}`")]
-#[help("remove the dependency or add `use {$extern_crate} as _;` to the crate root")]
-pub(crate) struct UnusedCrateDependency {
-    pub extern_crate: Symbol,
-    pub local_crate: Symbol,
-}
-
 // FIXME(jdonszelmann): duplicated in rustc_attr_parsing, should be moved there completely.
 #[derive(Diagnostic)]
 #[diag(

diff --git a/compiler/rustc_lint_defs/src/lib.rs b/compiler/rustc_lint_defs/src/lib.rs
@@ -690,10 +690,6 @@ pub enum BuiltinLintDiag {
         /// Indicates if the named argument is used as a width/precision for formatting
         is_formatting_arg: bool,
     },
-    UnusedCrateDependency {
-        extern_crate: Symbol,
-        local_crate: Symbol,
-    },
     AttributeLint(AttributeLintKind),
 }
 

diff --git a/compiler/rustc_metadata/src/creader.rs b/compiler/rustc_metadata/src/creader.rs
@@ -23,15 +23,14 @@ use rustc_middle::bug;
 use rustc_middle::ty::data_structures::IndexSet;
 use rustc_middle::ty::{TyCtxt, TyCtxtFeed};
 use rustc_proc_macro::bridge::client::ProcMacro;
-use rustc_session::Session;
 use rustc_session::config::{
     CrateType, ExtendedTargetModifierInfo, ExternLocation, Externs, OptionsTargetModifiers,
     TargetModifier,
 };
 use rustc_session::cstore::{CrateDepKind, CrateSource, ExternCrate, ExternCrateSource};
-use rustc_session::lint::{self, BuiltinLintDiag};
 use rustc_session::output::validate_crate_name;
 use rustc_session::search_paths::PathKind;
+use rustc_session::{Session, lint};
 use rustc_span::def_id::DefId;
 use rustc_span::edition::Edition;
 use rustc_span::{DUMMY_SP, Ident, Span, Symbol, sym};
@@ -1211,7 +1210,7 @@ impl CStore {
                 lint::builtin::UNUSED_CRATE_DEPENDENCIES,
                 span,
                 ast::CRATE_NODE_ID,
-                BuiltinLintDiag::UnusedCrateDependency {
+                errors::UnusedCrateDependency {
                     extern_crate: name_interned,
                     local_crate: tcx.crate_name(LOCAL_CRATE),
                 },

diff --git a/compiler/rustc_metadata/src/errors.rs b/compiler/rustc_metadata/src/errors.rs
@@ -688,3 +688,11 @@ pub struct RawDylibMalformed {
     #[primary_span]
     pub span: Span,
 }
+
+#[derive(Diagnostic)]
+#[diag("extern crate `{$extern_crate}` is unused in crate `{$local_crate}`")]
+#[help("remove the dependency or add `use {$extern_crate} as _;` to the crate root")]
+pub(crate) struct UnusedCrateDependency {
+    pub extern_crate: Symbol,
+    pub local_crate: Symbol,
+}
diff --git a/library/core/src/fmt/num.rs b/library/core/src/fmt/num.rs
@@ -594,13 +594,15 @@ impl_Debug! {
 // Include wasm32 in here since it doesn't reflect the native pointer size, and
 // often cares strongly about getting a smaller code size.
 #[cfg(any(target_pointer_width = "64", target_arch = "wasm32"))]
+#[doc(auto_cfg = false)]
 mod imp {
     use super::*;
     impl_Display!(i8, u8, i16, u16, i32, u32, i64, u64, isize, usize; as u64 into display_u64);
     impl_Exp!(i8, u8, i16, u16, i32, u32, i64, u64, isize, usize; as u64 into exp_u64);
 }
 
 #[cfg(not(any(target_pointer_width = "64", target_arch = "wasm32")))]
+#[doc(auto_cfg = false)]
 mod imp {
     use super::*;
     impl_Display!(i8, u8, i16, u16, i32, u32, isize, usize; as u32 into display_u32);

diff --git a/src/tools/compiletest/src/runtest.rs b/src/tools/compiletest/src/runtest.rs
@@ -1921,10 +1921,7 @@ impl<'test> TestCx<'test> {
 
         // Allow tests to use internal and incomplete features.
         compiler.args(&["-A", "internal_features"]);
-        // FIXME(#154168); temporarily exclude some directories to make the transition easier
-        if !input_file.iter().any(|p| p == "specialization") {
-            compiler.args(&["-A", "incomplete_features"]);
-        }
+        compiler.args(&["-A", "incomplete_features"]);
 
         // Allow tests to have unused parens and braces.
         // Add #![deny(unused_parens, unused_braces)] to the test file if you want to

diff --git a/tests/ui/specialization/assoc-ty-graph-cycle.rs b/tests/ui/specialization/assoc-ty-graph-cycle.rs
@@ -2,7 +2,7 @@
 
 // Make sure we don't crash with a cycle error during coherence.
 
-#![feature(specialization)] //~ WARN the feature `specialization` is incomplete
+#![feature(specialization)]
 
 trait Trait<T> {
     type Assoc;

diff --git a/tests/ui/specialization/assoc-ty-graph-cycle.stderr b/tests/ui/specialization/assoc-ty-graph-cycle.stderr
diff --git a/tests/ui/specialization/coherence/default-impl-normalization-ambig-2.rs b/tests/ui/specialization/coherence/default-impl-normalization-ambig-2.rs
@@ -1,5 +1,5 @@
 // regression test for #118987
-#![feature(specialization)] //~ WARN the feature `specialization` is incomplete
+#![feature(specialization)]
 
 trait Assoc {
     type Output;

diff --git a/tests/ui/specialization/coherence/default-impl-normalization-ambig-2.stderr b/tests/ui/specialization/coherence/default-impl-normalization-ambig-2.stderr
@@ -1,13 +1,3 @@
-warning: the feature `specialization` is incomplete and may not be safe to use and/or cause compiler crashes
-  --> $DIR/default-impl-normalization-ambig-2.rs:2:12
-   |
-LL | #![feature(specialization)]
-   |            ^^^^^^^^^^^^^^
-   |
-   = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
-   = help: consider using `min_specialization` instead, which is more stable and complete
-   = note: `#[warn(incomplete_features)]` on by default
-
 error[E0277]: the trait bound `u16: Assoc` is not satisfied
   --> $DIR/default-impl-normalization-ambig-2.rs:17:14
    |
@@ -20,6 +10,6 @@ help: the trait `Assoc` is implemented for `u8`
 LL | impl Assoc for u8 {}
    | ^^^^^^^^^^^^^^^^^
 
-error: aborting due to 1 previous error; 1 warning emitted
+error: aborting due to 1 previous error
 
 For more information about this error, try `rustc --explain E0277`.
diff --git a/tests/ui/specialization/coherence/default-item-normalization-ambig-1.rs b/tests/ui/specialization/coherence/default-item-normalization-ambig-1.rs
@@ -1,5 +1,5 @@
 // regression test for #73299.
-#![feature(specialization)] //~ WARN the feature `specialization` is incomplete
+#![feature(specialization)]
 
 trait X {
     type U;

diff --git a/tests/ui/specialization/coherence/default-item-normalization-ambig-1.stderr b/tests/ui/specialization/coherence/default-item-normalization-ambig-1.stderr
@@ -1,13 +1,3 @@
-warning: the feature `specialization` is incomplete and may not be safe to use and/or cause compiler crashes
-  --> $DIR/default-item-normalization-ambig-1.rs:2:12
-   |
-LL | #![feature(specialization)]
-   |            ^^^^^^^^^^^^^^
-   |
-   = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
-   = help: consider using `min_specialization` instead, which is more stable and complete
-   = note: `#[warn(incomplete_features)]` on by default
-
 error[E0119]: conflicting implementations of trait `Y` for type `<() as X>::U`
   --> $DIR/default-item-normalization-ambig-1.rs:20:1
    |
@@ -16,6 +6,6 @@ LL | impl Y for <() as X>::U {}
 LL | impl Y for <i32 as X>::U {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^ conflicting implementation for `<() as X>::U`
 
-error: aborting due to 1 previous error; 1 warning emitted
+error: aborting due to 1 previous error
 
 For more information about this error, try `rustc --explain E0119`.
diff --git a/tests/ui/specialization/cross-crate-defaults.rs b/tests/ui/specialization/cross-crate-defaults.rs
@@ -2,7 +2,7 @@
 
 //@ aux-build:cross_crates_defaults.rs
 
-#![feature(specialization)] //~ WARN the feature `specialization` is incomplete
+#![feature(specialization)]
 
 extern crate cross_crates_defaults;
 

diff --git a/tests/ui/specialization/cross-crate-defaults.stderr b/tests/ui/specialization/cross-crate-defaults.stderr
diff --git a/tests/ui/specialization/ctfe/default-assoc-const.rs b/tests/ui/specialization/ctfe/default-assoc-const.rs
@@ -1,7 +1,6 @@
 //! Regression test for revealing associated types through specialization during const eval.
 //@ check-pass
 #![feature(specialization)]
-//~^ WARNING the feature `specialization` is incomplete and may not be safe to use
 
 trait Foo {
     const ASSOC: usize;

diff --git a/tests/ui/specialization/ctfe/default-assoc-const.stderr b/tests/ui/specialization/ctfe/default-assoc-const.stderr
diff --git a/tests/ui/specialization/ctfe/default-assoc-type.rs b/tests/ui/specialization/ctfe/default-assoc-type.rs
@@ -2,7 +2,6 @@
 //! even if they rely on specialization.
 //@ check-pass
 #![feature(specialization)]
-//~^ WARNING the feature `specialization` is incomplete and may not be safe to use
 
 trait Foo {
     type Assoc: Trait;

diff --git a/tests/ui/specialization/ctfe/default-assoc-type.stderr b/tests/ui/specialization/ctfe/default-assoc-type.stderr
diff --git a/tests/ui/specialization/default-associated-type-bound-1.rs b/tests/ui/specialization/default-associated-type-bound-1.rs
@@ -2,7 +2,6 @@
 // bounds on them.
 
 #![feature(specialization)]
-//~^ WARNING `specialization` is incomplete
 
 trait X {
     type U: Clone;

diff --git a/tests/ui/specialization/default-associated-type-bound-1.stderr b/tests/ui/specialization/default-associated-type-bound-1.stderr
@@ -1,27 +1,17 @@
-warning: the feature `specialization` is incomplete and may not be safe to use and/or cause compiler crashes
-  --> $DIR/default-associated-type-bound-1.rs:4:12
-   |
-LL | #![feature(specialization)]
-   |            ^^^^^^^^^^^^^^
-   |
-   = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
-   = help: consider using `min_specialization` instead, which is more stable and complete
-   = note: `#[warn(incomplete_features)]` on by default
-
 error[E0277]: the trait bound `str: Clone` is not satisfied
-  --> $DIR/default-associated-type-bound-1.rs:18:22
+  --> $DIR/default-associated-type-bound-1.rs:17:22
    |
 LL |     default type U = str;
    |                      ^^^ the trait `Clone` is not implemented for `str`
    |
 help: the trait `Clone` is implemented for `String`
   --> $SRC_DIR/alloc/src/string.rs:LL:COL
 note: required by a bound in `X::U`
-  --> $DIR/default-associated-type-bound-1.rs:8:13
+  --> $DIR/default-associated-type-bound-1.rs:7:13
    |
 LL |     type U: Clone;
    |             ^^^^^ required by this bound in `X::U`
 
-error: aborting due to 1 previous error; 1 warning emitted
+error: aborting due to 1 previous error
 
 For more information about this error, try `rustc --explain E0277`.
diff --git a/tests/ui/specialization/default-associated-type-bound-2.rs b/tests/ui/specialization/default-associated-type-bound-2.rs
@@ -1,6 +1,5 @@
 // Check that generic predicates are also checked for default associated types.
 #![feature(specialization)]
-//~^ WARNING `specialization` is incomplete
 
 trait X<T> {
     type U: PartialEq<T>;

diff --git a/tests/ui/specialization/default-associated-type-bound-2.stderr b/tests/ui/specialization/default-associated-type-bound-2.stderr
@@ -1,22 +1,12 @@
-warning: the feature `specialization` is incomplete and may not be safe to use and/or cause compiler crashes
-  --> $DIR/default-associated-type-bound-2.rs:2:12
-   |
-LL | #![feature(specialization)]
-   |            ^^^^^^^^^^^^^^
-   |
-   = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
-   = help: consider using `min_specialization` instead, which is more stable and complete
-   = note: `#[warn(incomplete_features)]` on by default
-
 error[E0277]: can't compare `&'static B` with `B`
-  --> $DIR/default-associated-type-bound-2.rs:16:22
+  --> $DIR/default-associated-type-bound-2.rs:15:22
    |
 LL |     default type U = &'static B;
    |                      ^^^^^^^^^^ no implementation for `&'static B == B`
    |
    = help: the trait `PartialEq<B>` is not implemented for `&'static B`
 note: required by a bound in `X::U`
-  --> $DIR/default-associated-type-bound-2.rs:6:13
+  --> $DIR/default-associated-type-bound-2.rs:5:13
    |
 LL |     type U: PartialEq<T>;
    |             ^^^^^^^^^^^^ required by this bound in `X::U`
@@ -25,6 +15,6 @@ help: consider introducing a `where` clause, but there might be an alternative b
 LL | impl<B: 'static, T> X<B> for T where &'static B: PartialEq<B> {
    |                                ++++++++++++++++++++++++++++++
 
-error: aborting due to 1 previous error; 1 warning emitted
+error: aborting due to 1 previous error
 
 For more information about this error, try `rustc --explain E0277`.
diff --git a/tests/ui/specialization/default-generic-associated-type-bound.rs b/tests/ui/specialization/default-generic-associated-type-bound.rs
@@ -1,7 +1,6 @@
 // Check that default generics associated types are validated.
 
 #![feature(specialization)]
-//~^ WARNING `specialization` is incomplete
 
 trait X {
     type U<'a>: PartialEq<&'a Self> where Self: 'a;

diff --git a/tests/ui/specialization/default-generic-associated-type-bound.stderr b/tests/ui/specialization/default-generic-associated-type-bound.stderr
@@ -1,22 +1,12 @@
-warning: the feature `specialization` is incomplete and may not be safe to use and/or cause compiler crashes
-  --> $DIR/default-generic-associated-type-bound.rs:3:12
-   |
-LL | #![feature(specialization)]
-   |            ^^^^^^^^^^^^^^
-   |
-   = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
-   = help: consider using `min_specialization` instead, which is more stable and complete
-   = note: `#[warn(incomplete_features)]` on by default
-
 error[E0277]: can't compare `T` with `T`
-  --> $DIR/default-generic-associated-type-bound.rs:17:26
+  --> $DIR/default-generic-associated-type-bound.rs:16:26
    |
 LL |     default type U<'a> = &'a T;
    |                          ^^^^^ no implementation for `T == T`
    |
    = note: required for `&'a T` to implement `PartialEq`
 note: required by a bound in `X::U`
-  --> $DIR/default-generic-associated-type-bound.rs:7:17
+  --> $DIR/default-generic-associated-type-bound.rs:6:17
    |
 LL |     type U<'a>: PartialEq<&'a Self> where Self: 'a;
    |                 ^^^^^^^^^^^^^^^^^^^ required by this bound in `X::U`
@@ -25,6 +15,6 @@ help: consider further restricting type parameter `T` with trait `PartialEq`
 LL | impl<T: 'static + std::cmp::PartialEq> X for T {
    |                 +++++++++++++++++++++
 
-error: aborting due to 1 previous error; 1 warning emitted
+error: aborting due to 1 previous error
 
 For more information about this error, try `rustc --explain E0277`.
diff --git a/tests/ui/specialization/defaultimpl/allowed-cross-crate.rs b/tests/ui/specialization/defaultimpl/allowed-cross-crate.rs
@@ -5,7 +5,7 @@
 
 //@ aux-build:go_trait.rs
 
-#![feature(specialization)] //~ WARN the feature `specialization` is incomplete
+#![feature(specialization)]
 
 extern crate go_trait;
 

diff --git a/tests/ui/specialization/defaultimpl/allowed-cross-crate.stderr b/tests/ui/specialization/defaultimpl/allowed-cross-crate.stderr
diff --git a/tests/ui/specialization/defaultimpl/out-of-order.rs b/tests/ui/specialization/defaultimpl/out-of-order.rs
@@ -2,7 +2,7 @@
 
 // Test that you can list the more specific impl before the more general one.
 
-#![feature(specialization)] //~ WARN the feature `specialization` is incomplete
+#![feature(specialization)]
 
 trait Foo {
     type Out;