[llvm-cov][MC/DC] "Branch not found in Decisions" when handling variadic macros

[whentojump]

I hit this problem in https://elixir.bootlin.com/linux/v6.1.83/source/kernel/rcu/tasks.h#L1621

A reduced user-space program is:

#define FOO(x, ...) "", ##__VA_ARGS__
#define ZERO 0
int main() { FOO(, 1 && ZERO); }

Compiler explorer link.

Note that despite the same message, this issue should be different than #87000 and with #89869 locally applied I'm still seeing the same problem.

cc @evodius96 @chapuni

[chapuni]

Would it crash clang if #89572 is applied?

[whentojump]

I will try it very soon. And in general I love this proposal in #89572! Thanks