[Bug][C] Invalid DDG on single variable if-statements (Identifier)

[mahaloz]

Describe the bug
Single variable special if-statements don't have the correct data dependency edges and location in the DDG.

I used the following code:

int main(int argc) {
    if (argc) {
        puts("hello world");
    }
    return 0;
}

Note the special syntax on if(argc), which is equal to if(argc!=0). In a normal DDG, the if argc line should be dependent on argc.

Instead, I get the following graph:

if (argc) is shown to have no predecessors aside from the start, which is not correct. If you change the above to be argc!=0, the DDG is correct.

I believe this bug is related to or is a regression of #2833.

To Reproduce
Put the code above into a C file, then import it.
Run the following line:

cpg.method("main").dotDdg.l

You should get the same dot graph shown above.

Expected behavior
The correct graph looks like the following:

It shows that if(argc) depends on argc.

Desktop (please complete the following information):

• MacOS
• Joern v4.0.150