From: Sylvestre Ledru <sylvestre@debian.org>
Date: Thu, 14 Aug 2014 16:09:45 +0000 (+0000)
Subject: Document -Wtautological-pointer-compare & -Wtautological-undefined-compare with example
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=cc2ffe2aaba037e5746140432374609a25338c60;p=clang

Document -Wtautological-pointer-compare & -Wtautological-undefined-compare with example

git-svn-id: https://llvm.org/svn/llvm-project/cfe/branches/release_35@215651 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/docs/ReleaseNotes.rst b/docs/ReleaseNotes.rst
index c7c701be99..995f906534 100644
--- a/docs/ReleaseNotes.rst
+++ b/docs/ReleaseNotes.rst
@@ -70,6 +70,38 @@ about them. The improvements since the 3.4 release include:
 - New warning `-Wabsolute-value`: Clang warns about incorrect or useless usage
   of the absolute functions (`abs`, `fabsf`, etc).
 
+- New warning `-Wtautological-pointer-compare`:
+
+  .. code-block:: c++
+
+    #include <stddef.h>
+    void foo() {
+     int arr[5];
+     int x;
+     // warn on these conditionals
+     if (foo);
+     if (arr);
+     if (&x);
+     if (foo == NULL);
+     if (arr == NULL);
+     if (&x == NULL);
+    }
+
+  returns
+  `warning: comparison of address of 'x' equal to a null pointer is always false [-Wtautological-pointer-compare]`
+
+- New warning `-Wtautological-undefined-compare`: 
+
+  .. code-block:: c++
+
+    #include <stddef.h>
+    void f(int &x) {
+       if (&x == nullptr) { }
+    }
+
+  returns
+  `warning: reference cannot be bound to dereferenced null pointer in well-defined C++ code; comparison may be assumed to always evaluate to false [-Wtautological-undefined-compare]`
+
 -  ...
 
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