'do_not_remove',
         'vlib/v/tests/const_fixed_array_containing_references_to_itself_test.v', // error C2099: initializer is not a constant
         'vlib/v/tests/const_and_global_with_same_name_test.v', // error C2099: initializer is not a constant
+        'vlib/v/tests/sumtype_as_cast_test.v', // error: cannot support compound statement expression ({expr; expr; expr;})
     ]
     skip_on_windows               = [
         'do_not_remove',

     mut expr_type_sym := g.table.sym(g.unwrap_generic(node.expr_type))
     if mut expr_type_sym.info is ast.SumType {
         dot := if node.expr_type.is_ptr() { '->' } else { '.' }
-        if sym.info is ast.FnType {
-            g.write('/* as */ (${styp})__as_cast(')
+        if node.expr is ast.CallExpr && !g.is_cc_msvc {
+            tmp_var := g.new_tmp_var()
+            expr_styp := g.typ(node.expr_type)
+            g.write('({ ${expr_styp} ${tmp_var} = ')
+            g.expr(node.expr)
+            g.write('; ')
+            if sym.info is ast.FnType {
+                g.write('/* as */ (${styp})__as_cast(')
+            } else {
+                g.write('/* as */ *(${styp}*)__as_cast(')
+            }
+            g.write(tmp_var)
+            g.write(dot)
+            g.write('_${sym.cname},')
+            g.write(tmp_var)
+            g.write(dot)
+            sidx := g.type_sidx(unwrapped_node_typ)
+            g.write('_typ, ${sidx}); }) /*expected idx: ${sidx}, name: ${sym.name} */ ')
         } else {
-            g.write('/* as */ *(${styp}*)__as_cast(')
+            if sym.info is ast.FnType {
+                g.write('/* as */ (${styp})__as_cast(')
+            } else {
+                g.write('/* as */ *(${styp}*)__as_cast(')
+            }
+            g.write('(')
+            g.expr(node.expr)
+            g.write(')')
+            g.write(dot)
+            g.write('_${sym.cname},')
+            g.write('(')
+            g.expr(node.expr)
+            g.write(')')
+            g.write(dot)
+            // g.write('typ, /*expected:*/$node.typ)')
+            sidx := g.type_sidx(unwrapped_node_typ)
+            g.write('_typ, ${sidx}) /*expected idx: ${sidx}, name: ${sym.name} */ ')
         }
-        g.write('(')
-        g.expr(node.expr)
-        g.write(')')
-        g.write(dot)
-        g.write('_${sym.cname},')
-        g.write('(')
-        g.expr(node.expr)
-        g.write(')')
-        g.write(dot)
-        // g.write('typ, /*expected:*/$node.typ)')
-        sidx := g.type_sidx(unwrapped_node_typ)
-        g.write('_typ, ${sidx}) /*expected idx: ${sidx}, name: ${sym.name} */ ')
 
         // fill as cast name table
         for variant in expr_type_sym.info.variants {

new file mode 100644
+type Sum = int | string
+
+struct Count {
+mut:
+    count int
+}
+
+fn (mut c Count) ret_sum() Sum {
+    c.count++
+    return c.count
+}
+
+fn test_sumtype_as_cast() {
+    mut cnt := Count{22}
+    _ := cnt.ret_sum() as int
+    println(cnt)
+    assert cnt.count == 23
+}