the backtrace.
Sometimes backtraces can be confusing without implying corruption.
-Compiler optimizations can cause surprising behavior. For example, when
-a function has called another function as its final action (a @dfn{tail
-call}), the calling function may not appear in a backtrace at all.
+Compiler optimizations can cause surprising behavior. When a function
+has called another function as its final action (a @dfn{tail call}), the
+calling function may not appear in a backtrace at all. Similarly, when
+function A calls another function B that never returns, the compiler may
+optimize such that an unrelated function C appears in the backtrace
+instead of A. Function C is simply the function that happens to be in
+memory just after A. In the threads project, this is commonly seen in
+backtraces for test failures; see @ref{The pass function fails, ,
+@func{pass} Fails}), for more information.
@menu
* Backtrace Example::