<html>
<head>
<base href="https://bugs.llvm.org/">
</head>
<body><table border="1" cellspacing="0" cellpadding="8">
<tr>
<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - diagnose_if should try harder to find violations"
href="https://bugs.llvm.org/show_bug.cgi?id=40417">40417</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>diagnose_if should try harder to find violations
</td>
</tr>
<tr>
<th>Product</th>
<td>clang
</td>
</tr>
<tr>
<th>Version</th>
<td>unspecified
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
<tr>
<th>OS</th>
<td>Linux
</td>
</tr>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>enhancement
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
<tr>
<th>Component</th>
<td>-New Bugs
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>redbeard0531@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>htmldeveloper@gmail.com, llvm-bugs@lists.llvm.org, neeilans@live.com, richard-llvm@metafoo.co.uk
</td>
</tr></table>
<p>
<div>
<pre>This code compiles without warnings, even though (at least with -O2) the
compiler clearly knows that that there are violations since it is emitting
unchecked calls to boom(). This makes this feature much less useful since it
can only catch direct violations, which are the most likely to be noticed by
humans. It would be much more useful as a general static analysis hint if some
of these other cases could also be detected and warned on. The last example is
particularly interesting to us because it is a slightly simplified version of
where we tried to use diagnose_if until we saw that it was unable to detect
anything.
<a href="https://godbolt.org/z/QfCCux">https://godbolt.org/z/QfCCux</a>
void boom();
inline void semi_static_assert(bool arg)
__attribute__((diagnose_if(!arg, "boom", "warning"))) {
if (!arg) boom();
}
inline bool always_false() {return false;}
struct bool_holder {
bool is_true() const { return b; }
bool b;
};
void test() {
// semi_static_assert(false); // warns
// no warnings from the rest
semi_static_assert(always_false());
bool also_false = false;
semi_static_assert(also_false);
semi_static_assert(bool_holder{false}.is_true());
}</pre>
</div>
</p>
<hr>
<span>You are receiving this mail because:</span>
<ul>
<li>You are on the CC list for the bug.</li>
</ul>
</body>
</html>