Introduce new-style attribute parsers for several attributes

note: compiler compiles but librustdoc and clippy don't

compiler/rustc_attr_parsing/src/session_diagnostics.rs

@@ -6,9 +6,16 @@ use rustc_errors::{Applicability, Diag, DiagCtxtHandle, Diagnostic, EmissionGuar
 use rustc_macros::{Diagnostic, Subdiagnostic};
 use rustc_span::{Span, Symbol};
 
-use crate::attributes::util::UnsupportedLiteralReason;
 use crate::fluent_generated as fluent;
 
+pub(crate) enum UnsupportedLiteralReason {
+    Generic,
+    CfgString,
+    CfgBoolean,
+    DeprecatedString,
+    DeprecatedKvPair,
+}
+
 #[derive(Diagnostic)]
 #[diag(attr_parsing_expected_one_cfg_pattern, code = E0536)]
 pub(crate) struct ExpectedOneCfgPattern {
@@ -39,6 +46,21 @@ pub(crate) struct MultipleItem {
 pub(crate) struct IncorrectMetaItem {
     #[primary_span]
     pub span: Span,
+
+    #[subdiagnostic]
+    pub suggestion: Option<IncorrectMetaItemSuggestion>,
+}
+
+#[derive(Subdiagnostic)]
+#[multipart_suggestion(
+    attr_parsing_incorrect_meta_item_suggestion,
+    applicability = "maybe-incorrect"
+)]
+pub(crate) struct IncorrectMetaItemSuggestion {
+    #[suggestion_part(code = "\"")]
+    pub lo: Span,
+    #[suggestion_part(code = "\"")]
+    pub hi: Span,
 }
 
 /// Error code: E0541
@@ -337,13 +359,6 @@ pub(crate) struct RustcPromotablePairing {
     pub span: Span,
 }
 
-#[derive(Diagnostic)]
-#[diag(attr_parsing_rustc_const_stable_indirect_pairing)]
-pub(crate) struct RustcConstStableIndirectPairing {
-    #[primary_span]
-    pub span: Span,
-}
-
 #[derive(Diagnostic)]
 #[diag(attr_parsing_rustc_allowed_unstable_pairing, code = E0789)]
 pub(crate) struct RustcAllowedUnstablePairing {
@@ -423,3 +438,44 @@ pub(crate) struct UnknownVersionLiteral {
     #[primary_span]
     pub span: Span,
 }
+
+// FIXME(jdonszelmann) duplicated from `rustc_passes`, remove once `check_attr` is integrated.
+#[derive(Diagnostic)]
+#[diag(attr_parsing_unused_multiple)]
+pub(crate) struct UnusedMultiple {
+    #[primary_span]
+    #[suggestion(code = "", applicability = "machine-applicable")]
+    pub this: Span,
+    #[note]
+    pub other: Span,
+    pub name: Symbol,
+}
+
+#[derive(Diagnostic)]
+#[diag(attr_parsing_stability_outside_std, code = E0734)]
+pub(crate) struct StabilityOutsideStd {
+    #[primary_span]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(attr_parsing_empty_confusables)]
+pub(crate) struct EmptyConfusables {
+    #[primary_span]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(attr_parsing_repr_ident, code = E0565)]
+pub(crate) struct ReprIdent {
+    #[primary_span]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(attr_parsing_unrecognized_repr_hint, code = E0552)]
+#[help]
+pub(crate) struct UnrecognizedReprHint {
+    #[primary_span]
+    pub span: Span,
+}