Suggest minimal subset features in incomplete_features lint

compiler/rustc_lint/src/builtin.rs

@@ -2288,12 +2288,20 @@ impl EarlyLintPass for IncompleteFeatures {
                             n, n,
                         ));
                     }
+                    if HAS_MIN_FEATURES.contains(&name) {
+                        builder.help(&format!(
+                            "consider using `min_{}` instead, which is more stable and complete",
+                            name,
+                        ));
+                    }
                     builder.emit();
                 })
             });
     }
 }
 
+const HAS_MIN_FEATURES: &[Symbol] = &[sym::const_generics, sym::specialization];
+
 declare_lint! {
     /// The `invalid_value` lint detects creating a value that is not valid,
     /// such as a NULL reference.

src/test/ui/array-slice-vec/match_arr_unknown_len.stderr

@@ -6,6 +6,7 @@ LL | #![feature(const_generics)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #44580 <https://github.com/rust-lang/rust/issues/44580> for more information
+   = help: consider using `min_const_generics` instead, which is more stable and complete
 
 error[E0308]: mismatched types
   --> $DIR/match_arr_unknown_len.rs:6:9

src/test/ui/associated-types/defaults-specialization.stderr

@@ -6,6 +6,7 @@ LL | #![feature(associated_type_defaults, specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = 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
 
 error[E0053]: method `make` has an incompatible type for trait
   --> $DIR/defaults-specialization.rs:19:18

src/test/ui/binding/const-param.stderr

@@ -6,6 +6,7 @@ LL | #![feature(const_generics)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #44580 <https://github.com/rust-lang/rust/issues/44580> for more information
+   = help: consider using `min_const_generics` instead, which is more stable and complete
 
 error[E0158]: const parameters cannot be referenced in patterns
   --> $DIR/const-param.rs:7:9

src/test/ui/coherence/coherence-inherited-assoc-ty-cycle-err.stderr

@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = 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
 
 error[E0391]: cycle detected when building specialization graph of trait `Trait`
   --> $DIR/coherence-inherited-assoc-ty-cycle-err.rs:9:1

src/test/ui/const-generics/defaults/wrong-order.full.stderr

@@ -14,6 +14,7 @@ LL | #![cfg_attr(full, feature(const_generics))]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #44580 <https://github.com/rust-lang/rust/issues/44580> for more information
+   = help: consider using `min_const_generics` instead, which is more stable and complete
 
 error: aborting due to previous error; 1 warning emitted
 

src/test/ui/const-generics/issues/issue-56445.full.stderr

@@ -6,6 +6,7 @@ LL | #![cfg_attr(full, feature(const_generics))]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #44580 <https://github.com/rust-lang/rust/issues/44580> for more information
+   = help: consider using `min_const_generics` instead, which is more stable and complete
 
 error[E0771]: use of non-static lifetime `'a` in const generic
   --> $DIR/issue-56445.rs:9:26

src/test/ui/const-generics/issues/issue-60818-struct-constructors.full.stderr

@@ -6,6 +6,7 @@ LL | #![cfg_attr(full, feature(const_generics))]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #44580 <https://github.com/rust-lang/rust/issues/44580> for more information
+   = help: consider using `min_const_generics` instead, which is more stable and complete
 
 warning: 1 warning emitted
 

src/test/ui/const-generics/issues/issue-61336-1.full.stderr

@@ -6,6 +6,7 @@ LL | #![cfg_attr(full, feature(const_generics))]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #44580 <https://github.com/rust-lang/rust/issues/44580> for more information
+   = help: consider using `min_const_generics` instead, which is more stable and complete
 
 warning: 1 warning emitted
 

src/test/ui/const-generics/issues/issue-61336-2.full.stderr

@@ -6,6 +6,7 @@ LL | #![cfg_attr(full, feature(const_generics))]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #44580 <https://github.com/rust-lang/rust/issues/44580> for more information
+   = help: consider using `min_const_generics` instead, which is more stable and complete
 
 error[E0277]: the trait bound `T: Copy` is not satisfied
   --> $DIR/issue-61336-2.rs:10:5

src/test/ui/const-generics/issues/issue-61336.full.stderr

@@ -6,6 +6,7 @@ LL | #![cfg_attr(full, feature(const_generics))]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #44580 <https://github.com/rust-lang/rust/issues/44580> for more information
+   = help: consider using `min_const_generics` instead, which is more stable and complete
 
 error[E0277]: the trait bound `T: Copy` is not satisfied
   --> $DIR/issue-61336.rs:10:5

src/test/ui/const-generics/issues/issue-61422.full.stderr

@@ -6,6 +6,7 @@ LL | #![cfg_attr(full, feature(const_generics))]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #44580 <https://github.com/rust-lang/rust/issues/44580> for more information
+   = help: consider using `min_const_generics` instead, which is more stable and complete
 
 warning: 1 warning emitted
 

src/test/ui/const-generics/issues/issue-61432.full.stderr

@@ -6,6 +6,7 @@ LL | #![cfg_attr(full, feature(const_generics))]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #44580 <https://github.com/rust-lang/rust/issues/44580> for more information
+   = help: consider using `min_const_generics` instead, which is more stable and complete
 
 warning: 1 warning emitted
 

src/test/ui/const-generics/issues/issue-61747.full.stderr

@@ -6,6 +6,7 @@ LL | #![cfg_attr(full, feature(const_generics))]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #44580 <https://github.com/rust-lang/rust/issues/44580> for more information
+   = help: consider using `min_const_generics` instead, which is more stable and complete
 
 error: constant expression depends on a generic parameter
   --> $DIR/issue-61747.rs:8:23

src/test/ui/const-generics/occurs-check/unify-fixpoint.stderr

@@ -6,6 +6,7 @@ LL | #![feature(const_generics)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #44580 <https://github.com/rust-lang/rust/issues/44580> for more information
+   = help: consider using `min_const_generics` instead, which is more stable and complete
 
 error: constant expression depends on a generic parameter
   --> $DIR/unify-fixpoint.rs:9:32

src/test/ui/consts/trait_specialization.stderr

@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = 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
 
 warning: 1 warning emitted
 

src/test/ui/error-codes/E0520.stderr

@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = 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
 
 error[E0520]: `fly` specializes an item from a parent `impl`, but that item is not marked `default`
   --> $DIR/E0520.rs:17:5

src/test/ui/error-codes/E0730.stderr

@@ -6,6 +6,7 @@ LL | #![feature(const_generics)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #44580 <https://github.com/rust-lang/rust/issues/44580> for more information
+   = help: consider using `min_const_generics` instead, which is more stable and complete
 
 error[E0730]: cannot pattern-match on an array without a fixed length
   --> $DIR/E0730.rs:6:9

src/test/ui/error-codes/E0771.stderr

@@ -6,6 +6,7 @@ LL | #![feature(const_generics)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #44580 <https://github.com/rust-lang/rust/issues/44580> for more information
+   = help: consider using `min_const_generics` instead, which is more stable and complete
 
 error[E0771]: use of non-static lifetime `'a` in const generic
   --> $DIR/E0771.rs:4:41

src/test/ui/hygiene/generic_params.stderr

@@ -6,6 +6,7 @@ LL | #![feature(decl_macro, rustc_attrs, const_generics)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #44580 <https://github.com/rust-lang/rust/issues/44580> for more information
+   = help: consider using `min_const_generics` instead, which is more stable and complete
 
 warning: 1 warning emitted
 

src/test/ui/hygiene/issue-61574-const-parameters.stderr

@@ -6,6 +6,7 @@ LL | #![feature(const_generics)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #44580 <https://github.com/rust-lang/rust/issues/44580> for more information
+   = help: consider using `min_const_generics` instead, which is more stable and complete
 
 warning: 1 warning emitted
 

src/test/ui/impl-trait/equality-rpass.stderr

@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = 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
 
 warning: 1 warning emitted
 

src/test/ui/impl-trait/equality.stderr

@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = 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
 
 error[E0308]: mismatched types
   --> $DIR/equality.rs:15:5

src/test/ui/impl-trait/equality2.stderr

@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = 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
 
 error[E0308]: mismatched types
   --> $DIR/equality2.rs:25:18

src/test/ui/issues/issue-35376.stderr

@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = 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
 
 warning: 1 warning emitted
 

src/test/ui/issues/issue-55380.stderr

@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = 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
 
 warning: 1 warning emitted
 

src/test/ui/issues/issue-59508-1.stderr

@@ -12,6 +12,7 @@ LL | #![feature(const_generics)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #44580 <https://github.com/rust-lang/rust/issues/44580> for more information
+   = help: consider using `min_const_generics` instead, which is more stable and complete
 
 error: aborting due to previous error; 1 warning emitted
 

src/test/ui/overlap-doesnt-conflict-with-specialization.stderr

@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = 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
 
 warning: 1 warning emitted
 

src/test/ui/parser/assoc-static-semantic-fail.stderr

@@ -170,6 +170,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = 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
 
 error: aborting due to 24 previous errors; 1 warning emitted
 

src/test/ui/parser/default.stderr

@@ -31,6 +31,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = 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
 
 error[E0046]: not all trait items implemented, missing: `foo`
   --> $DIR/default.rs:22:1

src/test/ui/parser/trait-item-with-defaultness-fail-semantic.stderr

@@ -54,6 +54,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = 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
 
 error: aborting due to 6 previous errors; 1 warning emitted
 

src/test/ui/polymorphization/const_parameters/closures.stderr

@@ -6,6 +6,7 @@ LL | #![feature(const_generics, rustc_attrs)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #44580 <https://github.com/rust-lang/rust/issues/44580> for more information
+   = help: consider using `min_const_generics` instead, which is more stable and complete
 
 error: item has unused generic parameters
   --> $DIR/closures.rs:19:19

src/test/ui/polymorphization/const_parameters/functions.stderr

@@ -6,6 +6,7 @@ LL | #![feature(const_generics, rustc_attrs)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #44580 <https://github.com/rust-lang/rust/issues/44580> for more information
+   = help: consider using `min_const_generics` instead, which is more stable and complete
 
 error: item has unused generic parameters
   --> $DIR/functions.rs:15:8

src/test/ui/polymorphization/generators.stderr

@@ -6,6 +6,7 @@ LL | #![feature(const_generics, generators, generator_trait, rustc_attrs)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #44580 <https://github.com/rust-lang/rust/issues/44580> for more information
+   = help: consider using `min_const_generics` instead, which is more stable and complete
 
 error: item has unused generic parameters
   --> $DIR/generators.rs:36:5

src/test/ui/resolve/issue-65035-static-with-parent-generics.stderr

@@ -48,6 +48,7 @@ LL | #![feature(const_generics)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #44580 <https://github.com/rust-lang/rust/issues/44580> for more information
+   = help: consider using `min_const_generics` instead, which is more stable and complete
 
 error: aborting due to 5 previous errors; 1 warning emitted
 

src/test/ui/rfc-2497-if-let-chains/disallowed-positions.stderr

@@ -507,6 +507,7 @@ LL | #![feature(const_generics)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #44580 <https://github.com/rust-lang/rust/issues/44580> for more information
+   = help: consider using `min_const_generics` instead, which is more stable and complete
 
 warning: the feature `let_chains` is incomplete and may not be safe to use and/or cause compiler crashes
   --> $DIR/disallowed-positions.rs:22:12

src/test/ui/specialization/assoc-ty-graph-cycle.stderr

@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = 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
 
 warning: 1 warning emitted
 

src/test/ui/specialization/cross-crate-defaults.stderr

@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = 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
 
 warning: 1 warning emitted
 

src/test/ui/specialization/deafult-associated-type-bound-1.stderr

@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = 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
 
 error[E0277]: the trait bound `str: Clone` is not satisfied
   --> $DIR/deafult-associated-type-bound-1.rs:19:5

src/test/ui/specialization/deafult-associated-type-bound-2.stderr

@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = 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
 
 error[E0277]: can't compare `&'static B` with `B`
   --> $DIR/deafult-associated-type-bound-2.rs:16:5

src/test/ui/specialization/deafult-generic-associated-type-bound.stderr

@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = 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
 
 warning: the feature `generic_associated_types` is incomplete and may not be safe to use and/or cause compiler crashes
   --> $DIR/deafult-generic-associated-type-bound.rs:4:12

src/test/ui/specialization/defaultimpl/allowed-cross-crate.stderr

@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = 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
 
 warning: 1 warning emitted
 

src/test/ui/specialization/defaultimpl/out-of-order.stderr

@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = 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
 
 warning: 1 warning emitted
 

src/test/ui/specialization/defaultimpl/overlap-projection.stderr

@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = 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
 
 warning: 1 warning emitted
 

src/test/ui/specialization/defaultimpl/projection.stderr

@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = 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
 
 warning: 1 warning emitted
 

src/test/ui/specialization/defaultimpl/specialization-no-default.stderr

@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = 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
 
 error[E0520]: `foo` specializes an item from a parent `impl`, but that item is not marked `default`
   --> $DIR/specialization-no-default.rs:20:5

src/test/ui/specialization/defaultimpl/specialization-trait-item-not-implemented-rpass.stderr

@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = 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
 
 warning: 1 warning emitted
 

src/test/ui/specialization/defaultimpl/specialization-trait-item-not-implemented.stderr

@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = 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
 
 error[E0046]: not all trait items implemented, missing: `foo_two`
   --> $DIR/specialization-trait-item-not-implemented.rs:18:1