Why is this an issue?

always_comb block should not contain any non-blocking assignments.

How to fix it

Code examples

Noncompliant code example

always_comb begin
  y <= 0; // Noncompliant: Non-blocking assignment
  z = 1;
end

Compliant solution

always_comb begin
  y = 0; // Compliant: Blocking assignment
  z = 1;
end

Resources

Articles & blog posts

• lowRISC Verilog Coding Style Guide - Language Features - Combinational Logic
• Nonblocking Assignments in Verilog Synthesis, Coding Styles That Kill! - SNUG-2000 - Clifford E. Cummings