fix type propagation of struct fields bit accesses

src/Convert/Struct.hs

@@ -460,7 +460,7 @@ convertAsgn structs types (lhs, expr) =
             if maybeFields == Nothing
                 then (Implicit Unspecified [], Bit (Dot e' x) i)
                 else if Map.notMember structTf structs
-                        then (fieldType, Bit (Dot e' x) i)
+                        then (dropInnerTypeRange fieldType, Bit (Dot e' x) i)
                         else (dropInnerTypeRange fieldType, Bit e' i')
             where
                 (subExprType, e') = convertSubExpr e

test/basic/struct_bit_struct.sv

+typedef struct packed {
+    logic [3:0] a;
+    logic [3:0] b;
+} pair;
+
+typedef struct packed {
+    pair [1:0] x;
+    pair [1:0] y;
+} pair_list_pair;
+
+module Example(data, p1, p2, out_x, out_y);
+    input pair_list_pair data;
+    input logic p1;
+    input logic p2;
+    output logic [3:0] out_x;
+    output logic [3:0] out_y;
+
+    assign out_x = p2 ? data.x[p1].a : data.x[p1].b;
+    assign out_y = p2 ? data.y[p1].a : data.y[p1].b;
+endmodule

test/basic/struct_bit_struct.v

+module Example(data, p1, p2, out_x, out_y);
+    input wire [31:0] data;
+    input wire p1, p2;
+    output wire [3:0] out_x;
+    output wire [3:0] out_y;
+
+    assign out_x = p2 ? data[p1 * 8 + 20 +:4] : data[p1 * 8 + 16 +:4];
+    assign out_y = p2 ? data[p1 * 8 +  4 +:4] : data[p1 * 8 +  0 +:4];
+endmodule

test/basic/struct_bit_struct_tb.v

+module top;
+    reg [31:0] data;
+    reg p1, p2;
+    wire [3:0] out_x;
+    wire [3:0] out_y;
+
+    Example example(data, p1, p2, out_x, out_y);
+
+    task exhaust;
+        begin
+            #1 p1 = 0;
+            #1 p2 = 0;
+            #1 p1 = 0;
+            #1 p2 = 1;
+            #1 p1 = 1;
+            #1 p2 = 0;
+            #1 p1 = 1;
+            #1 p2 = 1;
+        end
+    endtask
+
+    initial begin
+        $monitor("%2d %b %b %b %b %b", $time,
+            data, p1, p2, out_x, out_y);
+        #1 data = 32'ha7107338;
+        exhaust;
+        #1 data = 32'h8f8259e4;
+        exhaust;
+        #1 data = 32'h80ad046a;
+        exhaust;
+        #1 data = 32'hbf93017e;
+        exhaust;
+        #1 data = 32'he6458a2d;
+        exhaust;
+    end
+endmodule