interface conversion respects shadowed variables

test/basic/interface_task.v

@@ -0,0 +1,21 @@
+module top;
+    task i_x;
+        input reg [31:0] i;
+        $display("I x(%0d)", i);
+    endtask
+    wire [31:0] w = 31;
+    wire [31:0] y = 42;
+    task x;
+        input reg [31:0] a, b;
+        $display("x('{%0d, %0d})", a, b);
+    endtask
+    task automatic z;
+        input reg [31:0] a, b;
+        $display("z('{%0d, %0d})", a, b);
+    endtask
+    initial begin
+        i_x(y);
+        x(w, y);
+        z(w, y);
+    end
+endmodule