[Gardening] UPDATE - use let chain to unwrap snippet and evaluate flag

Author: JhonnyBillM

compiler/rustc_typeck/src/errors.rs

@@ -270,12 +270,9 @@ impl<'a> SessionDiagnostic<'a> for MissingTypeParams {
         err.span_label(self.def_span, rustc_errors::fluent::typeck::label);
 
         let mut suggested = false;
-        if let (Some(snippet), true) = (
-            self.span_snippet,
-            // Don't suggest setting the type params if there are some already: the order is
-            // tricky to get right and the user will already know what the syntax is.
-            self.empty_generic_args,
-        ) {
+        // Don't suggest setting the type params if there are some already: the order is
+        // tricky to get right and the user will already know what the syntax is.
+        if let Some(snippet) = self.span_snippet && self.empty_generic_args {
             if snippet.ends_with('>') {
                 // The user wrote `Trait<'a, T>` or similar. To provide an accurate suggestion
                 // we would have to preserve the right order. For now, as clearly the user is