Clarify when fix-it hints on warnings are appropriate

Summary:
This is not a change in the rules, it's meant as a clarification about
warnings. Since the recovery from warnings is a no-op, the fix-it hints
on warnings shouldn't change anything. Anything that doesn't just
suppress the warning and changes the meaning of the code (even if it's
for the better) should be on an additional note.

Reviewers: rsmith, aaron.ballman

Reviewed By: aaron.ballman

Subscribers: cfe-commits, thakis

Tags: #clang

Differential Revision: https://reviews.llvm.org/D62470

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@362266 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/docs/InternalsManual.rst b/docs/InternalsManual.rst
index 7779310ee4979733b763e569611f47b7f71c337a..e1b5bd7c78f24a9097ac41e86297e4de77179120 100644 (file)
--- a/docs/InternalsManual.rst
+++ b/docs/InternalsManual.rst
@@ -423,6 +423,9 @@ Fix-it hints on errors and warnings need to obey these rules:
   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 must not change the meaning of the code.
+  However, a hint may clarify the meaning as intentional, for example by adding
+  parentheses when the precedence of operators isn't obvious.
 
 If a fix-it can't obey these rules, put the fix-it on a note.  Fix-its on notes
 are not applied automatically.