linting, moving error to session diagnostics

compiler/rustc_attr_parsing/src/attributes/stability.rs

@@ -452,8 +452,6 @@ pub(crate) fn parse_unstability<S: Stage>(
 
     match (feature, issue) {
         (Ok(feature), Ok(_)) => {
-            // Validate that unstable attributes don't use already-stable language features
-            
             if ACCEPTED_LANG_FEATURES.iter().any(|f| f.name == feature) {
                 cx.emit_err(session_diagnostics::UnstableAttrForAlreadyStableFeature {
                     attr_span: cx.attr_span,
@@ -461,7 +459,7 @@ pub(crate) fn parse_unstability<S: Stage>(
                 });
                 return None;
             }
-            
+
             let level = StabilityLevel::Unstable {
                 reason: UnstableReason::from_opt_reason(reason),
                 issue: issue_num,

compiler/rustc_attr_parsing/src/session_diagnostics.rs

@@ -1046,3 +1046,14 @@ pub(crate) struct CustomMirIncompatibleDialectAndPhase {
     #[label("... is not compatible with this phase")]
     pub phase_span: Span,
 }
+
+#[derive(Diagnostic)]
+#[diag("can't mark as unstable using an already stable feature")]
+pub(crate) struct UnstableAttrForAlreadyStableFeature {
+    #[primary_span]
+    #[label("this feature is already stable")]
+    #[help("consider removing the attribute")]
+    pub attr_span: Span,
+    #[label("the stability attribute annotates this item")]
+    pub item_span: Span,
+}

compiler/rustc_passes/src/check_attr.rs

@@ -16,9 +16,7 @@
 use rustc_data_structures::thin_vec::ThinVec;
 use rustc_data_structures::unord::UnordMap;
 use rustc_errors::{DiagCtxtHandle, IntoDiagArg, MultiSpan, StashKey, msg};
-use rustc_feature::{
-    AttributeDuplicates, AttributeType, BUILTIN_ATTRIBUTE_MAP, BuiltinAttribute,
-};
+use rustc_feature::{AttributeDuplicates, AttributeType, BUILTIN_ATTRIBUTE_MAP, BuiltinAttribute};
 use rustc_hir::attrs::diagnostic::Directive;
 use rustc_hir::attrs::{
     AttributeKind, DocAttribute, DocInline, EiiDecl, EiiImpl, EiiImplResolution, InlineAttr,
@@ -29,8 +27,7 @@
 use rustc_hir::intravisit::{self, Visitor};
 use rustc_hir::{
     self as hir, Attribute, CRATE_HIR_ID, Constness, FnSig, ForeignItem, GenericParamKind, HirId,
-    Item, ItemKind, MethodKind, Node, ParamName, PartialConstStability, Safety, Stability,
-    StabilityLevel, Target, TraitItem, find_attr,
+    Item, ItemKind, MethodKind, Node, ParamName, Safety, Target, TraitItem, find_attr,
 };
 use rustc_macros::Diagnostic;
 use rustc_middle::hir::nested_filter;
@@ -156,14 +153,8 @@ fn check_attributes(
                     self.check_proc_macro(hir_id, target, ProcMacroKind::Derive)
                 }
                 Attribute::Parsed(
-                    AttributeKind::Stability {
-                        span: attr_span,
-                        stability: Stability { level, feature },
-                    }
-                    | AttributeKind::RustcConstStability {
-                        span: attr_span,
-                        stability: PartialConstStability { level, feature, .. },
-                    },
+                    AttributeKind::Stability { .. }
+                    | AttributeKind::RustcConstStability { .. },
                 ) => {}
                 Attribute::Parsed(AttributeKind::Inline(InlineAttr::Force { .. }, ..)) => {} // handled separately below
                 Attribute::Parsed(AttributeKind::Inline(kind, attr_span)) => {

compiler/rustc_passes/src/errors.rs

@@ -871,17 +871,6 @@ pub(crate) struct CannotStabilizeDeprecated {
     pub item_sp: Span,
 }
 
-#[derive(Diagnostic)]
-#[diag("can't mark as unstable using an already stable feature")]
-pub(crate) struct UnstableAttrForAlreadyStableFeature {
-    #[primary_span]
-    #[label("this feature is already stable")]
-    #[help("consider removing the attribute")]
-    pub attr_span: Span,
-    #[label("the stability attribute annotates this item")]
-    pub item_span: Span,
-}
-
 #[derive(Diagnostic)]
 #[diag("{$descr} has missing stability attribute")]
 pub(crate) struct MissingStabilityAttr<'a> {