On 2020-07-09 10:45 +0100, Jonny Grant wrote:
> Hello!
>
> There is an example below, (my code is not like this example below). I'm
> reporting a possible issue, and asking if there is a way to detect it in code
> bases. If it's a real issue I can file a bug report on Bugzilla.
>
> Can gcc warn where code will not get to the 'return 3;' below?
>
> Cheers, Jonny
>
>
> int main(void)
> {
> const int i = 1;
> if(1 == i)
> {
> return 1;
> }
> else if(1 != i)
> {
> return 2;
> }
> else
> {
> return 3;
> }
> }
Generally finding all the branches in a program impossible to be executed is
unsolvable. Even in a program without any loop it's still NP-hard.
For some "simple" cases maybe we can implement some heuristics, or use a brute
force approach (as a part of -fanalyzer). But I doubt if these simple cases are
really useful.
--
Xi Ruoyao <xry111@xxxxxxxxxxxxxxxx>
School of Aerospace Science and Technology, Xidian University
