fix premature conversion of casts containing dimension queries

test/basic/package_function_cast.sv

@@ -0,0 +1,20 @@
+package P;
+    function automatic logic [7:0] f(input logic [2:0] p);
+        logic [7:0] r;
+        r = '0;
+        r[p+:2] = '1;
+        return r;
+    endfunction
+endpackage
+
+module top;
+    logic [2:0] p;
+    logic [7:0] q;
+    assign q = P::f(p);
+    initial begin
+        $monitor("%0d, p=%b q=%b", $time, p, q);
+        #1 p = 0;
+        while (p != 7)
+            #1 p = p + 1;
+    end
+endmodule

test/basic/package_function_cast.v

@@ -0,0 +1,18 @@
+module top;
+    function automatic [7:0] f;
+        input [2:0] p;
+        begin
+            f = 7'b0;
+            f[p+:2] = 2'b11;
+        end
+    endfunction
+    reg [2:0] p;
+    wire [7:0] q;
+    assign q = f(p);
+    initial begin
+        $monitor("%0d, p=%b q=%b", $time, p, q);
+        #1 p = 0;
+        while (p != 7)
+            #1 p = p + 1;
+    end
+endmodule