带位选择器和不带位选择器的赋值有什么区别？ (e/Specman)

Question

I'm coding in e (Specman) programming language. If I want to assign integer variable with constant, what is the difference if I use bit selector (selecting all 32 bits) or not?

I wanted to assign integer variable with negative constant in form: 32'b1... but this value was automatically cast to positive number (larger than MAX_INT) and I got the error. Then I tried using bit selector ([31:0]) on variable and assignment passed with no errors. Good number was assigned to variable. I'm not sure why is this case. What is the reason negative number is automatically cast when we don't use bit selector, and why not when we use it.

Code with error:

int_variable = 32'b111111111111111111111111

Code with no error:

int_variable[31:0] = 32'b111111111111111111111111

Answer 1

The docs say

In an assignment (lhs = rhs), the right-hand side (rhs) expression inherits the context of the left-hand side (lhs) expression

So your rhs expression should automatically be cast to -1 (assuming your code contains 32 or more 1's; for 31 1's you would get MAX_INT).

I don't think Specman gives an error for this.