Parameter info

Inside the parentheses of a call, an instance or a parameter list, View | Parameter Info (⌘P, Ctrl+P) shows what goes there, with the one at the caret highlighted. It also opens by itself shortly after you type (, and after you choose from the completion list a function, task, system task or macro that takes arguments.

Inside	Example	Shows
A function or task call	add(1, , obj.run(, pkg::twice(	Its arguments with direction, type and default: input byte data, output bit ok, input int retries = 3
A constructor call	super.new(, h = new(, my_item it = new( (also through a typedef of the class), h = my_item::new(	The arguments of the class’s own new; <no parameters> if it declares none (its implicit new() takes no arguments; constructors are not inherited)
A system task or function	$fopen(, $display(	Its arguments, as listed in IEEE 1800-2017 (filename, [type]; args… for any number)
A macro call	`MAX(1,	The macro’s formal arguments
An instance’s port list	counter u(.clk(clk), .count(, counter u(clk, , counter u[3:0](	The ports of the module, interface or program
A parameter value list	counter #(, registry #(.T(, pkg::registry #(	The parameters that can be overridden (not the localparams), with their defaults

The highlighted entry follows the caret: by position (the commas before the caret at the list’s own level; commas inside an argument’s parentheses, brackets or braces do not count), or, in a list connected by name, the one named after the . you are in (.count(, also while you are still typing the name: .cou); in a list connected by name, a position after a comma highlights nothing. A . inside an argument (s.lhs, bus.data) is member access, not a connection. When there are more arguments than parameters, nothing is highlighted and the signature is shown greyed out. Opened inside nested calls, it shows the innermost one (inside a parenthesized expression or a cast in an argument, the call around it); a popup open on a call stays while you type a nested call in its arguments, keeping its own highlighted argument. A function without arguments shows <no parameters>. It does not open in comments and strings (an open one stays while the caret is in a string argument), in a declaration’s own header (function int f(, module m #(), or when the name before ( does not resolve.

Try it

1. Open rtl/top.sv from the sample project and put the caret right after .count( in the instance u_counter. Press ⌘P (Ctrl+P): the popup shows the ports of counter, input logic clk, input logic rst_n, output logic [7:0] count, output logic done, with output logic [7:0] count highlighted.
2. Put the caret right after counter #( on the same line and press ⌘P (Ctrl+P): the popup shows the parameter int MAX = 10.
3. Open rtl/counter.sv, put the caret right after is_done( in the assign line and press ⌘P (Ctrl+P): the popup shows the argument of the package function, state_t s.
4. In rtl/counter.sv, on a new line after state_t state;, type initial $display(. The popup opens and shows args…. Undo.