--- gprbuild-2017/gpr/gpr.gpr.old	2017-05-27 20:59:07.061135892 +0200
+++ gprbuild-2017/gpr/gpr.gpr	2017-05-27 20:59:38.022638398 +0200
@@ -67,6 +67,7 @@
             for Switches ("gpr*.ad?") use
               Compiler'Default_Switches ("Ada") & ("-g1");
       end case;
+      for Driver ("C") use External ("CC", "gcc");
    end Compiler;
 
 end GPR;
--- gprbuild-gpl-2016-src/gpr/src/gpr-env.adb.old	2017-11-13 22:16:53.349083426 +0100
+++ gprbuild-gpl-2016-src/gpr/src/gpr-env.adb	2017-11-13 22:17:22.692590351 +0100
@@ -1948,6 +1948,8 @@
 
       end if;
 
+      Add_Directories (Self, "/usr/share/gpr");
+
       if Gpr_Prj_Path.all /= "" then
          Add_Directories (Self, Gpr_Prj_Path.all);
       end if;
--- gprbuild-gpl-2017-src/gpr/src/gpr-names.ads.old	2017-11-19 13:09:18.947527738 +0100
+++ gprbuild-gpl-2017-src/gpr/src/gpr-names.ads	2017-11-19 13:10:08.125654595 +0100
@@ -27,6 +27,8 @@
    Name_Buffer : String (1 .. 1_000_000);
    Name_Len    : Natural := 0;
 
+   Last_Id     : Name_Id := Name_Id'First;
+
    procedure Get_Name_String (Id : Name_Id);
    procedure Get_Name_String (Id : Unit_Name_Type);
    procedure Get_Name_String (Id : File_Name_Type);
--- gprbuild-gpl-2017-src/gpr/src/gpr-names.adb.old	2017-11-19 13:10:27.674316703 +0100
+++ gprbuild-gpl-2017-src/gpr/src/gpr-names.adb	2017-11-19 13:14:38.360963627 +0100
@@ -354,6 +354,8 @@
 
       Name_Chars.Append (ASCII.NUL);
 
+      Last_Id := Name_Entries.Last;
+
       return Name_Entries.Last;
    end Name_Enter;
 
@@ -427,6 +429,8 @@
 
       Name_Chars.Append (ASCII.NUL);
 
+      Last_Id := Name_Entries.Last;
+
       return Name_Entries.Last;
    end Name_Find;
 
--- gprbuild-gpl-2017-src/gpr/src/gpr-snames.adb.old	2017-11-19 13:12:41.592995718 +0100
+++ gprbuild-gpl-2017-src/gpr/src/gpr-snames.adb	2017-11-19 13:16:31.980979696 +0100
@@ -53,6 +53,10 @@
          return;
       end if;
 
+      if Last_Id = Name_Id'First then
+         Add_Name ("");
+      end if;
+
       Add_Name ("a");
       Add_Name ("b");
       Add_Name ("c");