https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95017
Bug ID: 95017
Summary: [coroutines] Failure to generate code for co_yield
expression if its the only statement in a loop
Product: gcc
Version: 10.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: lewissbaker.opensource at gmail dot com
Target Milestone: ---
See https://godbolt.org/z/v-Tkvi
Given a simple coroutine generator<T> type, if I compile the following
coroutine with GCC it fails to generate code for the 'co_yield' expression if
the co_yield is the only statement in the loop body.
However, if I add another statement after the co_yield then it correctly
generates code for the co_yield expression.
Works: -std=c++2a -fcoroutines -DWITH_EXTRA_STATEMENT
Fails: -std=c++2a -fcoroutines
---------------------
generator<double> test()
{
double i = 0;
while(i++ < 5) {
// If the second statement below is compiled-out then GCC fails to
generate
// code for the co_yield expression and the loop completes without
// ever suspending.
co_yield i * 2;
#ifdef WITH_EXTRA_STATEMENT
(void)i;
#endif
}
}
int main() {
for (auto i : test()) {
printf("%f\t", i);
}
}
---------------------
