ast_passes: use derive more

Signed-off-by: NDavid Wood <david.wood@huawei.com>

compiler/rustc_ast_passes/src/ast_validation.rs

@@ -14,6 +14,7 @@
 use rustc_ast_pretty::pprust::{self, State};
 use rustc_data_structures::fx::FxHashMap;
 use rustc_errors::{error_code, fluent, pluralize, struct_span_err, Applicability};
+use rustc_macros::Subdiagnostic;
 use rustc_parse::validate_attr;
 use rustc_session::lint::builtin::{
     DEPRECATED_WHERE_CLAUSE_LOCATION, MISSING_ABI, PATTERNS_IN_FNS_WITHOUT_BODY,
@@ -1782,15 +1783,17 @@ pub fn check_crate(session: &Session, krate: &Crate, lints: &mut LintBuffer) ->
 }
 
 /// Used to forbid `let` expressions in certain syntactic locations.
-#[derive(Clone, Copy)]
+#[derive(Clone, Copy, Subdiagnostic)]
 pub(crate) enum ForbiddenLetReason {
     /// `let` is not valid and the source environment is not important
     GenericForbidden,
     /// A let chain with the `||` operator
-    NotSupportedOr(Span),
+    #[note(ast_passes::not_supported_or)]
+    NotSupportedOr(#[primary_span] Span),
     /// A let chain with invalid parentheses
     ///
     /// For example, `let 1 = 1 && (expr && expr)` is allowed
     /// but `(let 1 = 1 && (let 1 = 1 && (let 1 = 1))) && let a = 1` is not
-    NotSupportedParentheses(Span),
+    #[note(ast_passes::not_supported_parentheses)]
+    NotSupportedParentheses(#[primary_span] Span),
 }

compiler/rustc_ast_passes/src/errors.rs

@@ -16,23 +16,6 @@ pub struct ForbiddenLet {
     pub(crate) reason: ForbiddenLetReason,
 }
 
-impl AddToDiagnostic for ForbiddenLetReason {
-    fn add_to_diagnostic_with<F>(self, diag: &mut Diagnostic, _: F)
-    where
-        F: Fn(&mut Diagnostic, SubdiagnosticMessage) -> SubdiagnosticMessage,
-    {
-        match self {
-            Self::GenericForbidden => {}
-            Self::NotSupportedOr(span) => {
-                diag.span_note(span, fluent::ast_passes::not_supported_or);
-            }
-            Self::NotSupportedParentheses(span) => {
-                diag.span_note(span, fluent::ast_passes::not_supported_parentheses);
-            }
-        }
-    }
-}
-
 #[derive(Diagnostic)]
 #[diag(ast_passes::forbidden_let_stable)]
 #[note]