Index: docs/InternalsManual.rst
===================================================================
--- docs/InternalsManual.rst
+++ docs/InternalsManual.rst
@@ -423,6 +423,9 @@
   driver, they should only be used when it's very likely they match the user's
   intent.
 * Clang must recover from errors as if the fix-it had been applied.
+* Fix-it hints on a warning should only clarify the meaning of the existing
+  code, not change it. Examples for such hints are added parentheses in cases
+  of counter-intuitive precedence, when they clarify the order of operations.
 
 If a fix-it can't obey these rules, put the fix-it on a note.  Fix-its on notes
 are not applied automatically.