Remove usage of LintContext::span_lint in clippy

Author: GuillaumeGomez

clippy_utils/src/diagnostics.rs

@@ -8,7 +8,7 @@
 //! Thank you!
 //! ~The `INTERNAL_METADATA_COLLECTOR` lint
 
-use rustc_errors::{Applicability, Diag, DiagMessage, MultiSpan};
+use rustc_errors::{Applicability, Diag, Diagnostic, DiagCtxtHandle, DiagMessage, Level, MultiSpan};
 #[cfg(debug_assertions)]
 use rustc_errors::{EmissionGuarantee, SubstitutionPart, Suggestions};
 use rustc_hir::HirId;
@@ -240,15 +240,25 @@ where
     M: Into<DiagMessage>,
     F: FnOnce(&mut Diag<'_, ()>),
 {
+    struct ClippyDiag<F: FnOnce(&mut Diag<'_, ()>)>(F);
+
+    impl<'a, F: FnOnce(&mut Diag<'_, ()>)> Diagnostic<'a, ()> for ClippyDiag<F> {
+        fn into_diag(self, dcx: DiagCtxtHandle<'a>, level: Level) -> Diag<'a, ()> {
+            let mut lint = Diag::new(dcx, level, "");
+            (self.0)(&mut lint);
+            lint
+        }
+    }
+
     #[expect(clippy::disallowed_methods)]
-    cx.span_lint(lint, sp, |diag| {
+    cx.emit_span_lint(lint, sp, ClippyDiag(|diag: &mut Diag<'_, ()>| {
         diag.primary_message(msg);
         f(diag);
         docs_link(diag, lint);
 
         #[cfg(debug_assertions)]
         validate_diag(diag);
-    });
+    }));
 }
 
 /// Like [`span_lint`], but emits the lint at the node identified by the given `HirId`.