Getting the variable name (IdentifierInfo?) from clang Expr* object of arguments for function calls

Question

I'm trying to get function call sequences using clang's Analyzer framework (With checkers and such).

I wrote a Checker that uses the checkPreCall method to handle function calls. I'm trying to look at simple function calls like f(x, y), and I want to see the name of the variable I'm passing to the function.

Using the fact that a Expr is a type of Stmt, I used the printPretty function to get the variable name, but obviously if the argument is x+2 or something like that I get x+2 as the output.

Is there a better way to retrieve the name of the variable, or even find out whether it's a simple expression (x) or a complex one (x+2)?