Only add bodies to system functions

by checking the name-prefix.

Author: petr-bauch

gnat2goto/driver/goto_utils.adb

@@ -30,6 +30,18 @@ package body GOTO_Utils is
       return R;
    end Make_Address_Of;
 
+   function Is_Prefix (Prefix : String; Base_String : String) return Boolean
+   is
+   begin
+      if Prefix'Length < Base_String'Length and then
+        Prefix = Base_String (Base_String'First .. Prefix'Length)
+      then
+         return True;
+      else
+         return False;
+      end if;
+   end Is_Prefix;
+
    -------------------
    -- Make_Int_Type --
    -------------------

gnat2goto/driver/goto_utils.ads

@@ -22,6 +22,8 @@ package GOTO_Utils is
 
    type String_Access is access String;
 
+   function Is_Prefix (Prefix : String; Base_String : String) return Boolean;
+
    package Addressed_Variables is new
      GNAT.Table (Table_Component_Type => String_Access,
             Table_Index_Type     => Natural,

gnat2goto/driver/tree_walk.adb

@@ -5460,7 +5460,8 @@ package body Tree_Walk is
       Default_Body : Irep := Make_Nil (Sloc (N));
    begin
       if List_Length (Parameter_Specifications (N)) = 1 and
-      not (Kind (Get_Return_Type (Subprog_Type)) = I_Void_Type)
+        not (Kind (Get_Return_Type (Subprog_Type)) = I_Void_Type) and
+        Is_Prefix ("system", Unique_Name (Defining_Unit_Name (N)))
       then
          Default_Body := Build_Identity_Body (Get_Parameters (Subprog_Type));
       end if;