[variadic] Print original functions in output

src/plugins/variadic/register.ml

@@ -20,8 +20,43 @@
 (*                                                                        *)
 (**************************************************************************)
 
+open Cil_types
+
 let category = File.register_code_transformation_category "variadic"
 
+(* Variadic will create prototype and specifications for some variadic
+   functions. Since only prototypes are created, the resulting source code isn't
+   compilable. This printer will print the original functions, with the replaced
+   prototypes in comments beside the instruction. *)
+let change_printer =
+  let first = ref true in
+  fun () ->
+    if !first then begin
+      first := false;
+      let module Printer_class(X: Printer.PrinterClass) = struct
+        class printer = object
+          inherit X.printer as super
+
+          method !instr fmt i =
+            match i with
+            (* If the instruction calls a function that have been replaced,
+               then build an instruction with the old function. *)
+            | Call(res, ({ enode = Lval(Var vi, o) } as fct), args, loc)
+              when Replacements.mem vi ->
+              let old_vi = Replacements.find vi in
+              let old_vi = { vi with vname = old_vi.vname } in
+              let old_instr =
+                Call(res, { fct with enode = Lval(Var old_vi, o) }, args, loc)
+              in
+              Format.fprintf fmt "%a /* %s */" super#instr old_instr vi.vname
+            (* Otherwise keep the instruction. *)
+            | _ ->
+              super#instr fmt i
+        end
+      end in
+      Printer.update_printer (module Printer_class: Printer.PrinterExtension)
+    end
+
 let () =
   Cmdline.run_after_extended_stage
     begin fun () ->
@@ -32,8 +67,10 @@ let () =
   Cmdline.run_after_configuring_stage
     begin fun () ->
       let translate file =
-        if Options.Enabled.get () then
+        if Options.Enabled.get () then begin
+          change_printer ();
           Translate.translate_variadics file
+        end
       in
       File.add_code_transformation_before_cleanup category translate
     end