Verilog Out-of-bound Method Declarations

An out-of-block method declaration signature should match its prototype declaration’s signature. Sigasi Studio flags an error if the prototype and the implementation signatures have a:

  • different subroutine form (task or function)
  • different return type, if it is a function
  • different arity or any argument has a:
    • different name
    • different direction
    • mismatched type

If an argument default value is present in an out-of-block method declaration but is missing in the prototype, or default values are not syntactically identical, a warning message is reported (rules 90, 91).

Errors are also reported for a missing prototype for out-of-bound definitions and missing or duplicated definitions for an extern method prototype.

class C;
    extern task proto_only();       // missing definition
    extern task who_am_i();
    extern function bit bad(input int a, b, c, d, e = 2 + 3);

    extern function int good(input int a, output string b);

function C::who_am_i();             // should be a task
    // ...

function C::no_proto();             // missing prototype
    // ...

function logic C::bad(              // should return bit
    output int a,                   // should be input
    input integer b,                // should be int
    input int si,                   // should be 'c'
    input int d = 4,                // should have no default value
    input int e = 5                 // should be same value as prototype: 2 + 3
    // ...

function bit C::bad(ref x, y);      // completely different signature, duplicate definition
    // ...

function int C::good(input int a, output string b);
    // ...

Rule configuration

These rules can be disabled for your project, or their severity and parameters can be modified in the project linting settings. Alternatively, they can be manually configured with the following template: