Make the comments clearer

Author: abgruszecki

compiler/src/dotty/tools/dotc/transform/FirstTransform.scala

@@ -147,9 +147,11 @@ class FirstTransform extends MiniPhase with InfoTransformer { thisPhase =>
     if (tree.isType) {
       toTypeTree(tree)
     } else if (tree.name != nme.WILDCARD) {
-      // We want to constant-fold _some_ idents here - for instance, @switch needs to see literals in patterns.
-      // However, constant-foldable wildcards can occur in patterns, for instance as `case _: "a"`;
-      // we avoid constant-folding those as doing so would change the meaning of the pattern.
+      // We constant-fold all idents except wildcards.
+      // AFAIK, constant-foldable wildcard idents can only occur in patterns, for instance as `case _: "a"`.
+      // Constant-folding that would result in `case "a": "a"`, which changes the meaning of the pattern.
+      // Note that we _do_ want to constant-fold idents in patterns that _aren't_ wildcards -
+      // for example, @switch annotation needs to see inlined literals and not indirect references.
       constToLiteral(tree)
     } else tree
 
@@ -163,8 +165,8 @@ class FirstTransform extends MiniPhase with InfoTransformer { thisPhase =>
     constToLiteral(foldCondition(tree))
 
   override def transformTyped(tree: Typed)(implicit ctx: Context): Tree =
-    // Singleton type cases (such as `case _: "a"`) are constant-foldable
-    // we avoid constant-folding those as doing so would change the meaning of the pattern
+    // Singleton type cases (such as `case _: "a"`) are constant-foldable.
+    // We avoid constant-folding those as doing so would change the meaning of the pattern (see transformIdent).
     if (!ctx.mode.is(Mode.Pattern)) constToLiteral(tree) else tree
 
   override def transformBlock(tree: Block)(implicit ctx: Context): Tree =