Support pattern assignments to const variables, bug616.

Changes

@@ -5,6 +5,8 @@ indicates the contributor was also the author of the fix; Thanks!
 
 * Verilator 3.846-devel
 
+****  Support pattern assignments to const variables, bug616. [Ed Lander]
+
 ****  Fix DETECTARRAY on packed structures, bug610. [Jeremy Bennett]
 
 ****  Fix LITENDIAN on unpacked structures, bug614. [Wai Sum Mong]

src/V3Width.cpp

@@ -1151,6 +1151,9 @@ private:
 		    patp->unlinkFrBack();
 		}
 	    }
+	    while (AstConstDType* classp = m_assDTypep->castConstDType()) {
+		m_assDTypep = classp->subDTypep()->skipRefp();
+	    }
 	    if (AstNodeClassDType* classp = m_assDTypep->castNodeClassDType()) {
 		// Due to "default" and tagged patterns, we need to determine
 		// which member each AstPatMember corresponds to before we can

test_regress/t/t_struct_init.v

@@ -39,6 +39,8 @@ module t;
       //      bit 	vec2d[2][3];
    } pack3_t;
 
+   const b4_t b4_const_a = '{1'b1, 1'b0, 1'b0, 1'b1};
+
    pack2_t arr[2];
 
    initial begin
@@ -94,6 +96,8 @@ module t;
 	 if (q != 4'b1011) $stop;
       end
 
+      if (b4_const_a != 4'b1001) $stop;
+
       $write("*-* All Finished *-*\n");
       $finish;
    end