Request for new warning for variable 'overloading' in var.randomize() calls

[jcurtiss8086]

A common bug that appears in testbench code involves randomizing an object from a scope where a variable exists with the same name as a variable in the object that is being randomized. Using the local:: prefix tells the compiler to use the local-scope variable, but when the coder forgets to use the local:: prefix, then very subtle bugs are introduced that are difficult to catch via visual-inspection/code-reviews.

In the example below, the code should have used x == local::y. A warning that can flag the name-overloading for y in this instance would help reduce the need for a lot of manual code-reviews and prevent a lot of coding bugs earlier in the process.

class A;
    rand int x;
    rand int y;
endclass

class B;

    function f();
        A a;
        int y = 5;
        a.randomize() with {
            x == y;   // Warning here that y is defined in both locally and in 'a' so 'a.y' is being used?
        };
    endfunction

endclass

[MikePopoloski]

This seems like a subcase of a more general warning set I'd like to add for "shadowing" declarations.

[jcurtiss8086]

If this scenario is included with the generalized shadowing-warning, then that's great! I'll want to promote all shadow warnings to errors.

Since I would assume that most shadowing-warnings will trigger at the declaration of the 2nd variable, and this case triggers at reference within a constraint, I can see an argument for having it handled by a separate -W option just to allow promotion/demotion to be set differently.

[MikePopoloski]

Hmm yeah that's true, in most other cases the shadowing is from a declaration but here it's via name reference. Definitely worth a separate -W.