fix early conversion cast struct types

CHANGELOG.md

@@ -15,6 +15,7 @@
 * Fixed `--write path/to/dir/` with directives like `` `default_nettype ``
 * Fixed `logic` incorrectly converted to `wire` even when provided to a task or
   function output port
+* Fixed conversion of fields accessed from explicitly-cast structs
 * Fixed conversion of enum item names and typenames nested deeply within the
   left-hand side of an assignment
 * Fixed `input signed` ports of interface-using modules producing invalid

src/Convert/Struct.hs

@@ -298,10 +298,6 @@ convertExpr scopes struct@(Struct _ fields []) (Pattern itemsOrig) =
                         Just value = numberToInteger n
                         Right (Number n) = item
 
-convertExpr scopes _ (Cast (Left t) expr) =
-    Cast (Left t') $ convertExpr scopes t expr
-    where t' = convertType t
-
 convertExpr scopes (Implicit _ []) expr =
     traverseSinglyNestedExprs (convertExpr scopes UnknownType) expr
 convertExpr scopes (Implicit sg rs) expr =
@@ -495,7 +491,7 @@ convertSubExpr scopes (Call e args) =
         (retType, _) = fallbackType scopes e
         args' = convertCall scopes e args
 convertSubExpr scopes (Cast (Left t) e) =
-    (t', Cast (Left t') e')
+    (t, Cast (Left t') e')
     where
         e' = convertExpr scopes t $ snd $ convertSubExpr scopes e
         t' = convertType t

test/core/struct_cast_dot.sv

@@ -0,0 +1,8 @@
+module top;
+    localparam type U = struct packed { integer s; };
+    localparam type T = struct packed { U x, y, z; };
+    localparam T L = '{x: '{s: 1}, y: '{s: 2}, z: '{s: 3}};
+    logic [L.x.s-1:0] a;
+    logic [T'(L).y.s-1:0] b;
+    logic [U'(T'(L).z).s-1:0] c;
+endmodule

test/core/struct_cast_dot.v

@@ -0,0 +1,5 @@
+module top;
+    wire a;
+    wire [1:0] b;
+    wire [2:0] c;
+endmodule