Merge pull request #77528 from DougGregor/macro-expansion-rtc-comment-fix

Finish thought in comment

Author: DougGregor

lib/Sema/TypeCheckAvailability.cpp

@@ -535,8 +535,8 @@ class TypeRefinementContextBuilder : private ASTWalker {
     return MacroWalking::Arguments;
   }
 
-  /// Check whether this declaration is in a source file buried within
-  /// a macro expansion of the
+  /// Check whether this declaration is within a macro expansion buffer that
+  /// will have its own type refinement context that will be lazily expanded.
   bool isDeclInMacroExpansion(Decl *decl) const override {
     // If it's not in a macro expansion relative to its context, it's not
     // considered to be in a macro expansion.