Set severity for non-rule diagnostics (#21559)

Author: senekor

crates/ruff_server/src/lint.rs

@@ -283,24 +283,27 @@ fn to_lsp_diagnostic(
         range = diagnostic_range.to_range(source_kind.source_code(), index, encoding);
     }
 
-    let (severity, tags, code) = if let Some(code) = code {
-        let code = code.to_string();
+    let (severity, code) = if let Some(code) = code {
+        (severity(code), code.to_string())
+    } else {
         (
-            Some(severity(&code)),
-            tags(diagnostic),
-            Some(lsp_types::NumberOrString::String(code)),
+            match diagnostic.severity() {
+                ruff_db::diagnostic::Severity::Info => lsp_types::DiagnosticSeverity::INFORMATION,
+                ruff_db::diagnostic::Severity::Warning => lsp_types::DiagnosticSeverity::WARNING,
+                ruff_db::diagnostic::Severity::Error => lsp_types::DiagnosticSeverity::ERROR,
+                ruff_db::diagnostic::Severity::Fatal => lsp_types::DiagnosticSeverity::ERROR,
+            },
+            diagnostic.id().to_string(),
         )
-    } else {
-        (None, None, None)
     };
 
     (
         cell,
         lsp_types::Diagnostic {
             range,
-            severity,
-            tags,
-            code,
+            severity: Some(severity),
+            tags: tags(diagnostic),
+            code: Some(lsp_types::NumberOrString::String(code)),
             code_description: diagnostic.documentation_url().and_then(|url| {
                 Some(lsp_types::CodeDescription {
                     href: lsp_types::Url::parse(url).ok()?,