Add a standard for control-flow unreachable assertions in functions that return

values, so as to avoid warnings on some platforms.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@51831 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 23 insertions, 0 deletions

diff --git a/docs/CodingStandards.html b/docs/CodingStandards.html
index 3a7f8b3d1e..a99e46e5b5 100644
--- a/docs/CodingStandards.html
+++ b/docs/CodingStandards.html
@@ -623,6 +623,29 @@ assert(isa<PHINode>(Succ->front()) && "Only works on PHId BBs!"
 
 <p>You get the idea...</p>
 
+<p>Please be aware when adding assert statements that not all compilers are aware of
+the semantics of the assert.  In some places, asserts are used to indicate a piece of
+code that should not be reached.  These are typically of the form:</p>
+
+<div class="doc_code">
+<pre>
+assert(0 && "Some helpful error message");
+</pre>
+</div>
+
+<p>When used in a function that returns a value, they should be followed with a return
+statement and a comment indicating that this line is never reached.  This will prevent
+a compiler which is unable to deduce that the assert statement never returns from
+generating a warning.</p>
+
+<div class="doc_code">
+<pre>
+assert(0 && "Some helpful error message");
+// Not reached
+return 0;
+</pre>
+</div>
+
 </div>
 
 <!-- _______________________________________________________________________ -->