Rollup merge of #131013 - matthiaskrgr:unwrapordefault, r=jieyouxu

cleanup: don't manually `unwrap_or_default()`

Author: matthiaskrgr

Diff for: compiler/rustc_expand/src/proc_macro_server.rs

@@ -627,8 +627,7 @@ impl server::TokenStream for Rustc<'_, '_> {
         base: Option<Self::TokenStream>,
         trees: Vec<TokenTree<Self::TokenStream, Self::Span, Self::Symbol>>,
     ) -> Self::TokenStream {
-        let mut stream =
-            if let Some(base) = base { base } else { tokenstream::TokenStream::default() };
+        let mut stream = base.unwrap_or_default();
         for tree in trees {
             for tt in (tree, &mut *self).to_internal() {
                 stream.push_tree(tt);
@@ -642,8 +641,7 @@ impl server::TokenStream for Rustc<'_, '_> {
         base: Option<Self::TokenStream>,
         streams: Vec<Self::TokenStream>,
     ) -> Self::TokenStream {
-        let mut stream =
-            if let Some(base) = base { base } else { tokenstream::TokenStream::default() };
+        let mut stream = base.unwrap_or_default();
         for s in streams {
             stream.push_stream(s);
         }

Diff for: compiler/rustc_hir_typeck/src/upvar.rs

@@ -1369,13 +1369,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         for (&var_hir_id, _) in upvars.iter() {
             let mut diagnostics_info = Vec::new();
 
-            let auto_trait_diagnostic = if let Some(diagnostics_info) =
-                self.compute_2229_migrations_for_trait(min_captures, var_hir_id, closure_clause)
-            {
-                diagnostics_info
-            } else {
-                FxIndexMap::default()
-            };
+            let auto_trait_diagnostic = self
+                .compute_2229_migrations_for_trait(min_captures, var_hir_id, closure_clause)
+                .unwrap_or_default();
 
             let drop_reorder_diagnostic = if let Some(diagnostics_info) = self
                 .compute_2229_migrations_for_drop(