Remove unnecessary min_specialization after bootstrap

These crates all needed specialization for `newtype_index!`, which will no
longer be necessary when the current nightly eventually becomes the next
bootstrap compiler.

compiler/rustc_ast/src/lib.rs

@@ -15,7 +15,7 @@
 #![feature(box_patterns)]
 #![feature(if_let_guard)]
 #![feature(let_chains)]
-#![feature(min_specialization)]
+#![cfg_attr(bootstrap, feature(min_specialization))]
 #![feature(negative_impls)]
 #![feature(stmt_expr_attributes)]
 

compiler/rustc_errors/src/lib.rs

@@ -7,6 +7,7 @@
 #![allow(internal_features)]
 #![allow(rustc::diagnostic_outside_of_impl)]
 #![allow(rustc::untranslatable_diagnostic)]
+#![cfg_attr(bootstrap, feature(min_specialization))]
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
 #![doc(rust_logo)]
 #![feature(array_windows)]
@@ -16,7 +17,6 @@
 #![feature(error_reporter)]
 #![feature(extract_if)]
 #![feature(let_chains)]
-#![feature(min_specialization)]
 #![feature(negative_impls)]
 #![feature(never_type)]
 #![feature(rustc_attrs)]

compiler/rustc_hir/src/lib.rs

@@ -5,7 +5,7 @@
 #![feature(associated_type_defaults)]
 #![feature(closure_track_caller)]
 #![feature(let_chains)]
-#![feature(min_specialization)]
+#![cfg_attr(bootstrap, feature(min_specialization))]
 #![feature(never_type)]
 #![feature(rustc_attrs)]
 #![feature(variant_count)]

compiler/rustc_hir_analysis/src/lib.rs

@@ -67,7 +67,7 @@ This API is completely unstable and subject to change.
 #![feature(is_sorted)]
 #![feature(iter_intersperse)]
 #![feature(let_chains)]
-#![feature(min_specialization)]
+#![cfg_attr(bootstrap, feature(min_specialization))]
 #![feature(never_type)]
 #![feature(lazy_cell)]
 #![feature(slice_partition_dedup)]

compiler/rustc_hir_typeck/src/lib.rs

@@ -5,7 +5,7 @@
 #![feature(try_blocks)]
 #![feature(never_type)]
 #![feature(box_patterns)]
-#![feature(min_specialization)]
+#![cfg_attr(bootstrap, feature(min_specialization))]
 #![feature(control_flow_enum)]
 
 #[macro_use]

compiler/rustc_infer/src/lib.rs

@@ -24,7 +24,7 @@
 #![feature(let_chains)]
 #![feature(if_let_guard)]
 #![feature(iterator_try_collect)]
-#![feature(min_specialization)]
+#![cfg_attr(bootstrap, feature(min_specialization))]
 #![feature(try_blocks)]
 #![recursion_limit = "512"] // For rustdoc
 

compiler/rustc_mir_build/src/lib.rs

@@ -9,7 +9,7 @@
 #![feature(box_patterns)]
 #![feature(if_let_guard)]
 #![feature(let_chains)]
-#![feature(min_specialization)]
+#![cfg_attr(bootstrap, feature(min_specialization))]
 #![feature(try_blocks)]
 
 #[macro_use]

compiler/rustc_mir_dataflow/src/lib.rs

@@ -2,7 +2,7 @@
 #![feature(box_patterns)]
 #![feature(exact_size_is_empty)]
 #![feature(let_chains)]
-#![feature(min_specialization)]
+#![cfg_attr(bootstrap, feature(min_specialization))]
 #![feature(try_blocks)]
 
 #[macro_use]

compiler/rustc_mir_transform/src/lib.rs

@@ -8,7 +8,7 @@
 #![feature(is_sorted)]
 #![feature(let_chains)]
 #![feature(map_try_insert)]
-#![feature(min_specialization)]
+#![cfg_attr(bootstrap, feature(min_specialization))]
 #![feature(never_type)]
 #![feature(option_get_or_insert_default)]
 #![feature(round_char_boundary)]

compiler/rustc_target/src/lib.rs

@@ -14,7 +14,7 @@
 #![feature(exhaustive_patterns)]
 #![feature(iter_intersperse)]
 #![feature(let_chains)]
-#![feature(min_specialization)]
+#![cfg_attr(bootstrap, feature(min_specialization))]
 #![feature(rustc_attrs)]
 #![feature(step_trait)]
 #![allow(internal_features)]

compiler/rustc_trait_selection/src/lib.rs

@@ -24,7 +24,7 @@
 #![feature(option_take_if)]
 #![feature(never_type)]
 #![feature(type_alias_impl_trait)]
-#![feature(min_specialization)]
+#![cfg_attr(bootstrap, feature(min_specialization))]
 #![recursion_limit = "512"] // For rustdoc
 
 #[macro_use]