https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115564
Bug ID: 115564
Summary: -Wanalyzer-infinite-loop false negative when there are
no source locations
Product: gcc
Version: unknown
Status: UNCONFIRMED
Keywords: diagnostic
Severity: normal
Priority: P3
Component: analyzer
Assignee: dmalcolm at gcc dot gnu.org
Reporter: dmalcolm at gcc dot gnu.org
Target Milestone: ---
Consider e.g.:
void test (unsigned b)
{
for (unsigned i = b; i >= 0; --i) {
}
}
-Wanalyzer-infinite-loop warns about this at -O1 and below:
https://godbolt.org/z/axze96331
but at -O2 and above we don't warn.
https://godbolt.org/z/xjGMnP3P5
The warning is rejected at:
if (inf_loop->m_loc == UNKNOWN_LOCATION)
{
if (get_logger ())
get_logger ()->log
("no location available for reporting infinite loop");
continue;
}
We have two basic blocks no statements, and location_t == UNKNOWN_LOCATION on
each of the edges connecting them.
Ideas for fixing:
* backtrack through the egraph to find the first useful location_t on a path to
the entry to the infinite loop
* ensure that location_t values are set on the CFG edges
