Static Analysis

Zephir's compiler provides static analysis of the compiled code. The idea behind this feature is to help the developer to find potential problems and avoid unexpected behaviors, well before runtime.

Conditional Unassigned Variables

Static Analysis of assignments tries to identify if a variable is used before it's assigned:

class Utils
{
    public function someMethod(b)
    {
        string a; char c;

        if b == 10 {
            let a = "hello";
        }

        //a could be unitialized here
        for c in a {
            echo c, PHP_EOL;
        }
    }
}

The above example illustrates a common situation. The variable a is assigned only when b is equal to 10, then it's required to use the value of this variable - but it could be uninitialized. Zephir detects this, automatically initializes the variable to an empty string, and generates a warning alerting the developer:

Warning: Variable 'a' was assigned for the first time in conditional branch,
consider initialize it in its declaration in
/home/scott/test/test/utils.zep on 21 [conditional-initialization]

    for c in a {

Finding such errors is sometimes tricky, however static analysis helps the programmer to find bugs in advance.

Dead Code Elimination

Zephir informs the developer about unreachable branches in the code and performs dead code elimination, which means it gets rid of all that code from the generated binary, since it cannot be executed anyway:

class Utils
{
    public function someMethod(b)
    {
        if false {
            // This is never executed
            echo "hello";
        }
    }
}