Possibly related to BUG 39799
The attached very simple test case does not produce any warning on build, using '-W -Wall -Wextra -O3 -Wuninitialized -Werror'.
If the condition is not seen as false at build time, the compiler does not complaint.
Created attachment 19570 [details]
Test case that should produce a warning with -O -Wuninitialized
The uninitialized use is optimized away before we would warn about it.
CCP removing the uninitialized value.
*** This bug has been marked as a duplicate of 18501 ***