Improve insert whitespace in mbe

Author: edwin0cheng

crates/hir-expand/src/builtin_fn_macro.rs

@@ -251,9 +251,13 @@ fn format_args_expand(
     }
     for arg in &mut args {
         // Remove `key =`.
-        if matches!(arg.token_trees.get(1), Some(tt::TokenTree::Leaf(tt::Leaf::Punct(p))) if p.char == '=' && p.spacing != tt::Spacing::Joint)
+        if matches!(arg.token_trees.get(1), Some(tt::TokenTree::Leaf(tt::Leaf::Punct(p))) if p.char == '=')
         {
-            arg.token_trees.drain(..2);
+            // but not with `==`
+            if !matches!(arg.token_trees.get(2), Some(tt::TokenTree::Leaf(tt::Leaf::Punct(p))) if p.char == '=' )
+            {
+                arg.token_trees.drain(..2);
+            }
         }
     }
     let _format_string = args.remove(0);

crates/mbe/src/syntax_bridge.rs

@@ -228,16 +228,7 @@ fn convert_tokens<C: TokenConvertor>(conv: &mut C) -> tt::Subtree {
             }
 
             let spacing = match conv.peek().map(|next| next.kind(conv)) {
-                Some(kind)
-                    if !kind.is_trivia()
-                        && kind.is_punct()
-                        && kind != T!['[']
-                        && kind != T!['{']
-                        && kind != T!['(']
-                        && kind != UNDERSCORE =>
-                {
-                    tt::Spacing::Joint
-                }
+                Some(kind) if !kind.is_trivia() => tt::Spacing::Joint,
                 _ => tt::Spacing::Alone,
             };
             let char = match token.to_char(conv) {