https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80460
Bug ID: 80460
Summary: Non-sensical fallthrough warning after [[noreturn]]
function leading to __builtin_unreachable()
Product: gcc
Version: 7.0.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: thiago at kde dot org
Target Milestone: ---
Testcase:
===
[[noreturn]] void qt_assert() noexcept;
inline void qt_noop() {}
void f(int i)
{
switch (i) {
case 0:
((!(!"message")) ? qt_assert() : qt_noop());
case 1:
qt_noop();
}
}
===
Prints (under -O2):
<source>: In function 'void f(int)':
<source>:8:49: warning: this statement may fall through
[-Wimplicit-fallthrough=]
((!(!"message")) ? qt_assert() : qt_noop());
~~~~~~~^~
<source>:9:5: note: here
case 1:
^~~~
The condition !!"message" is always true, so the [[noreturn]] function
qt_assert() will be called. There's no condition under which qt_noop() will be
called, so there's no fallthrough possible.
