diff --git a/extensions/analysis/bodies b/extensions/analysis/bodies
index 853c994c1..5964a1e24 100644
--- a/extensions/analysis/bodies
+++ b/extensions/analysis/bodies
@@ -83,6 +83,8 @@ is
    --  This creates a ref-counted object: we must decrease its ref-count
    --  whether we return normally or through an exception.
 begin
+   Libadalang.Project_Provider.Check_Source_Info (Tree);
+
    begin
       GPR_Impl.Initialize_Context_From_Project
         (Result, Tree, Project, EH_Int, With_Trivia, Tab_Stop);
diff --git a/extensions/src/libadalang-config_pragmas.adb b/extensions/src/libadalang-config_pragmas.adb
index 09b0dc5fc..02d6a786c 100644
--- a/extensions/src/libadalang-config_pragmas.adb
+++ b/extensions/src/libadalang-config_pragmas.adb
@@ -251,7 +251,7 @@ package body Libadalang.Config_Pragmas is
    begin
       return Import_From_Project
         (Context,
-         (Kind => GPR2_Kind, GPR2_Value => Tree.Reference),
+         (Kind => GPR2_Kind, GPR2_Value => Tree),
          (Kind => GPR2_Kind, GPR2_Value => View));
    end Import_From_Project;
 
diff --git a/extensions/src/libadalang-data_decomposition.adb b/extensions/src/libadalang-data_decomposition.adb
index 2408d7a14..41dbee53e 100644
--- a/extensions/src/libadalang-data_decomposition.adb
+++ b/extensions/src/libadalang-data_decomposition.adb
@@ -14,14 +14,18 @@ with GNATCOLL.Mmap;
 with GNATCOLL.OS.FS;
 with GNATCOLL.OS.Process;
 with GNATCOLL.VFS;
+pragma Warnings (Off, "not referenced");
+with GPR2.Build.Source.Sets;
+pragma Warnings (On, "not referenced");
 with GPR2.Containers;
 with GPR2.Context;
 with GPR2.Path_Name;
 with GPR2.Path_Name.Set;
 
-with Libadalang.Auto_Provider; use Libadalang.Auto_Provider;
-with Libadalang.Common;        use Libadalang.Common;
-with Libadalang.GPR_Utils;     use Libadalang.GPR_Utils;
+with Libadalang.Auto_Provider;    use Libadalang.Auto_Provider;
+with Libadalang.Common;           use Libadalang.Common;
+with Libadalang.GPR_Utils;        use Libadalang.GPR_Utils;
+with Libadalang.Project_Provider; use Libadalang.Project_Provider;
 
 package body Libadalang.Data_Decomposition is
 
@@ -2682,6 +2686,8 @@ package body Libadalang.Data_Decomposition is
 
       Args : Argument_List;
    begin
+      Check_Source_Info (Tree);
+
       Args.Append ("gprbuild");
       Args.Append ("-c");
       Args.Append ("-P" & String (Tree.Root_Project.Path_Name.Value));
@@ -2785,6 +2791,8 @@ package body Libadalang.Data_Decomposition is
       --  Look for JSON files for all Ada sources
 
       declare
+         use type GPR2.Language_Id;
+
          Actual_View   : constant GPR2.Project.View.Object :=
            (if View.Is_Defined then View else Tree.Root_Project);
          Loaded_Subdir : constant GPR2.Filename_Optional := Tree.Subdirs;
@@ -2800,7 +2808,8 @@ package body Libadalang.Data_Decomposition is
 
             Obj_Dir := V.Object_Directory;
             if Loaded_Subdir'Length > 0 then
-               pragma Assert (Obj_Dir.Simple_Name = Loaded_Subdir);
+               pragma Assert
+                 (V.Is_Runtime or else Obj_Dir.Simple_Name = Loaded_Subdir);
                Obj_Dir := Obj_Dir.Containing_Directory;
             end if;
             if Subdirs'Length > 0 then
@@ -2810,7 +2819,7 @@ package body Libadalang.Data_Decomposition is
             Trace.Trace ("Object directory: " & String (Obj_Dir.Value));
 
             for S of V.Sources loop
-               if S.Is_Ada then
+               if S.Language = GPR2.Ada_Language then
                   Trace.Trace
                     ("Processing Ada source: " & String (S.Path_Name.Value));
                   Repinfo_File :=
diff --git a/extensions/src/libadalang-gpr_utils.adb b/extensions/src/libadalang-gpr_utils.adb
index 3a71365cc..7baf74afd 100644
--- a/extensions/src/libadalang-gpr_utils.adb
+++ b/extensions/src/libadalang-gpr_utils.adb
@@ -9,14 +9,17 @@ with GNAT.Strings; use GNAT.Strings;
 
 with GNATCOLL.Utils;
 with GNATCOLL.VFS;        use GNATCOLL.VFS;
+with GPR2.Build.Source;
+pragma Warnings (Off, "not referenced");
+with GPR2.Build.Source.Sets;
+pragma Warnings (On, "not referenced");
+with GPR2.Build.Unit_Info;
 with GPR2.Containers;
 with GPR2.Path_Name;
 with GPR2.Project.Attribute;
 with GPR2.Project.Attribute.Set;
 with GPR2.Project.Attribute_Index;
-with GPR2.Project.Source;
 with GPR2.Project.View.Set;
-with GPR2.Unit;
 
 package body Libadalang.GPR_Utils is
 
@@ -425,13 +428,12 @@ package body Libadalang.GPR_Utils is
 
       when GPR2_Kind =>
          declare
-            Path : constant GPR2.Path_Name.Object :=
-              GPR2.Path_Name.Create_File
-                (GPR2.Filename_Type (Filename), GPR2.Path_Name.No_Resolution);
-            File : constant GPR2.Project.Source.Object :=
-              View.GPR2_Value.Source (Path);
+            use type GPR2.Language_Id;
+
+            File : constant GPR2.Build.Source.Object :=
+              View.GPR2_Value.Source (GPR2.Simple_Name (Filename));
          begin
-            return File.Is_Defined and then File.Is_Ada;
+            return File.Is_Defined and then File.Language = GPR2.Ada_Language;
          end;
       end case;
    end Is_Ada_Source;
@@ -511,32 +513,53 @@ package body Libadalang.GPR_Utils is
          --  instead of using this internal API.
 
          declare
-            procedure Process_Wrapper (Source : GPR2.Project.Source.Object);
+            procedure Process_Wrapper (Source : GPR2.Build.Source.Object);
             --  Call ``Process`` on all units in ``Source``
 
+            function Unit_Name (U : GPR2.Build.Unit_Info.Object) return String
+            is (String (U.Name)
+                & (if U.Kind in GPR2.S_Separate
+                   then "." & String (U.Separate_Name)
+                   else ""));
+
             ---------------------
             -- Process_Wrapper --
             ---------------------
 
-            procedure Process_Wrapper (Source : GPR2.Project.Source.Object) is
+            procedure Process_Wrapper (Source : GPR2.Build.Source.Object) is
                Filename : constant String := String (Source.Path_Name.Value);
             begin
+               if not Source.Has_Units then
+                  return;
+               end if;
+
                for U of Source.Units loop
-                  Process.all
-                    (Unit_Name => String (U.Name),
-                     Unit_Part => (if U.Kind in GPR2.Unit.Spec_Kind
-                                   then Unit_Spec
-                                   else Unit_Body),
-                     Filename  => Filename);
+
+                  --  TODO (eng/gpr/gpr-issues#227) GPR2 cannot find the name
+                  --  of some units. Discard them since we cannot do anything
+                  --  useful with them, and they may cause trouble later on
+                  --  (conflicting sources for the same empty unit name).
+
+                  declare
+                     N : constant String := Unit_Name (U);
+                  begin
+                     if N /= "" then
+                        Process.all
+                          (Unit_Name => N,
+                           Unit_Part => (if U.Kind in GPR2.S_Spec
+                                         then Unit_Spec
+                                         else Unit_Body),
+                           Filename  => Filename);
+                     end if;
+                  end;
                end loop;
             end Process_Wrapper;
          begin
             if Recursive then
-               Tree.GPR2_Value.For_Each_Source
-                 (View             => View.GPR2_Value,
-                  Action           => Process_Wrapper'Access,
-                  Language         => GPR2.Ada_Language,
-                  Externally_Built => True);
+               for V of View.GPR2_Value.Closure (Include_Self => True) loop
+                  Iterate_Ada_Units
+                    (Tree, (GPR2_Kind, V), Process, Recursive => False);
+               end loop;
             else
                for S of View.GPR2_Value.Sources loop
                   Process_Wrapper (S);
@@ -590,15 +613,19 @@ package body Libadalang.GPR_Utils is
 
          --  Also process compiler switches for all Ada sources
 
-         for Source of Indexes (Self, Switches) loop
-            declare
-               Filename : constant String := Source.To_String;
-            begin
-               if Is_Ada_Source (Tree, Self, Filename) then
-                  Process_Switches (Self, Switches, Filename);
-               end if;
-            end;
-         end loop;
+         declare
+            Index_List : constant XString_Array := Indexes (Self, Switches);
+         begin
+            for Source of Index_List loop
+               declare
+                  Filename : constant String := Source.To_String;
+               begin
+                  if Is_Ada_Source (Tree, Self, Filename) then
+                     Process_Switches (Self, Switches, Filename);
+                  end if;
+               end;
+            end loop;
+         end;
       end Process_View;
 
       ----------------------
diff --git a/extensions/src/libadalang-gpr_utils.ads b/extensions/src/libadalang-gpr_utils.ads
index 95125af0d..451d67353 100644
--- a/extensions/src/libadalang-gpr_utils.ads
+++ b/extensions/src/libadalang-gpr_utils.ads
@@ -29,8 +29,7 @@ private package Libadalang.GPR_Utils is
    type Any_Tree (Kind : Project_Kind := Project_Kind'First) is record
       case Kind is
          when GPR1_Kind => GPR1_Value : GPR1.Project_Tree_Access;
-         when GPR2_Kind =>
-           GPR2_Value : access constant GPR2.Project.Tree.Object;
+         when GPR2_Kind => GPR2_Value : GPR2.Project.Tree.Object;
       end case;
    end record;
 
diff --git a/extensions/src/libadalang-helpers.adb b/extensions/src/libadalang-helpers.adb
index 32899ee09..bc2e00afc 100644
--- a/extensions/src/libadalang-helpers.adb
+++ b/extensions/src/libadalang-helpers.adb
@@ -19,10 +19,7 @@ with GNAT.Traceback.Symbolic;
 with GNATCOLL.File_Paths;
 with GNATCOLL.Strings; use GNATCOLL.Strings;
 with GNATCOLL.VFS;     use GNATCOLL.VFS;
-with GPR2.Containers;
-with GPR2.Context;
-with GPR2.Path_Name;
-with GPR2.Project.Configuration;
+with GPR2.Options;
 with GPR2.Project.View;
 with GPR2.Project.View.Set;
 
@@ -510,8 +507,7 @@ package body Libadalang.Helpers is
 
                if Use_GPR2 then
                   App_Ctx.Provider :=
-                    (Kind         => GPR2_Project_File,
-                     GPR2_Project => GPR2_Project.Reference);
+                    (Kind => GPR2_Project_File, GPR2_Project => GPR2_Project);
                else
                   App_Ctx.Provider :=
                     (Kind => Project_File, Project => Project);
@@ -823,8 +819,8 @@ package body Libadalang.Helpers is
       Target, RTS, Config_File : String := "";
       Project                  : in out GPR2.Project.Tree.Object)
    is
-      Ctx   : GPR2.Context.Object;
-      Error : Boolean := False;
+      Options : GPR2.Options.Object;
+      Error   : Boolean := False;
 
       procedure Set_Scenario_Var (Name, Value : String);
       --  Set the given scenario variable in ``Ctx``
@@ -835,7 +831,7 @@ package body Libadalang.Helpers is
 
       procedure Set_Scenario_Var (Name, Value : String) is
       begin
-         Ctx.Include (GPR2.Name_Type (Name), Value);
+         Options.Add_Switch (GPR2.Options.X, Name & "=" & Value);
       end Set_Scenario_Var;
 
    begin
@@ -845,42 +841,28 @@ package body Libadalang.Helpers is
       Iterate_Scenario_Vars (Scenario_Vars, Set_Scenario_Var'Access);
 
       --  Load the project tree with either a config file (if given) or the
-      --  requested target/runtime , and beware of loading errors
+      --  requested target/runtime, and beware of loading errors
 
-      declare
-         PF      : constant GPR2.Path_Name.Object :=
-           GPR2.Path_Name.Create_File
-             (GPR2.Filename_Type (Project_File), GPR2.Path_Name.No_Resolution);
-         RTS_Map : GPR2.Containers.Lang_Value_Map;
       begin
-         if Config_File = "" then
-            if RTS /= "" then
-               RTS_Map.Include (GPR2.Ada_Language, RTS);
+         Options.Add_Switch (GPR2.Options.P, Project_File);
+
+         if Config_File /= "" then
+            if Target /= "" or else RTS /= "" then
+               Abort_App
+                 ("--config not allowed if --target or --RTS are passed");
             end if;
-            Project.Load_Autoconf
-              (Filename          => PF,
-               Context           => Ctx,
-               Target            => GPR2.Optional_Name_Type (Target),
-               Language_Runtimes => RTS_Map);
+            Options.Add_Switch (GPR2.Options.Config, Config_File);
+         end if;
 
-         elsif Target /= "" or else RTS /= "" then
-            Abort_App ("--config not allowed if --target or --RTS are passed");
+         if Target /= "" then
+            Options.Add_Switch (GPR2.Options.Target, Target);
+         end if;
 
-         else
-            declare
-               F      : constant GPR2.Path_Name.Object :=
-                 GPR2.Path_Name.Create_File (GPR2.Filename_Type (Config_File));
-               Config : constant GPR2.Project.Configuration.Object :=
-                 GPR2.Project.Configuration.Load (F);
-            begin
-               Project.Load
-                 (Filename => PF,
-                  Context  => Ctx,
-                  Config   => Config);
-            end;
+         if RTS /= "" then
+            Options.Add_Switch (GPR2.Options.RTS, RTS);
          end if;
 
-         Project.Update_Sources (With_Runtime => True);
+         Error := not Project.Load (Options);
       exception
          when Exc : GPR2.Project_Error =>
             Error := True;
@@ -888,14 +870,17 @@ package body Libadalang.Helpers is
               ("Loading failed: " & Exception_Message (Exc));
       end;
 
+      Error := Error or else not Update_Sources (Project);
+
       --  Whether the project loaded successfully or not, print messages since
       --  they may contain warnings. If there was an error, abort the App.
 
+      Error := Error or else Project.Log_Messages.Has_Error;
       Project.Log_Messages.Output_Messages
         (Information => False,
          Warning     => True,
          Error       => True);
-      if Error or else Project.Log_Messages.Has_Error then
+      if Error then
          Abort_App;
       end if;
 
diff --git a/extensions/src/libadalang-helpers.ads b/extensions/src/libadalang-helpers.ads
index 0525f13db..0d8ba6bf3 100644
--- a/extensions/src/libadalang-helpers.ads
+++ b/extensions/src/libadalang-helpers.ads
@@ -89,7 +89,7 @@ package Libadalang.Helpers is
          when Auto_Dir =>
             Dirs, Found_Files : String_Vectors.Vector;
          when GPR2_Project_File =>
-            GPR2_Project : access GPR2.Project.Tree.Object;
+            GPR2_Project : GPR2.Project.Tree.Object;
       end case;
    end record;
 
diff --git a/extensions/src/libadalang-preprocessing.adb b/extensions/src/libadalang-preprocessing.adb
index b721461e6..0ab179122 100644
--- a/extensions/src/libadalang-preprocessing.adb
+++ b/extensions/src/libadalang-preprocessing.adb
@@ -19,10 +19,11 @@ with GNATCOLL.Strings;  use GNATCOLL.Strings;
 with Langkit_Support.Slocs;  use Langkit_Support.Slocs;
 with Langkit_Support.Text;   use Langkit_Support.Text;
 
-with Libadalang.Common;    use Libadalang.Common;
-with Libadalang.GPR_Utils; use Libadalang.GPR_Utils;
-with Libadalang.PP_Impl;   use Libadalang.PP_Impl;
-with Libadalang.PP_Lexer;  use Libadalang.PP_Lexer;
+with Libadalang.Common;           use Libadalang.Common;
+with Libadalang.GPR_Utils;        use Libadalang.GPR_Utils;
+with Libadalang.PP_Impl;          use Libadalang.PP_Impl;
+with Libadalang.PP_Lexer;         use Libadalang.PP_Lexer;
+with Libadalang.Project_Provider; use Libadalang.Project_Provider;
 
 package body Libadalang.Preprocessing is
 
@@ -730,11 +731,11 @@ package body Libadalang.Preprocessing is
       Default_Config : out File_Config;
       File_Configs   : out File_Config_Maps.Map) is
    begin
+      Check_Source_Info (Tree);
+
       Extract_Preprocessor_Data_From_Project
-        (Tree           => (Kind       => GPR2_Kind,
-                            GPR2_Value => Tree'Unrestricted_Access),
-         View           => (Kind       => GPR2_Kind,
-                            GPR2_Value => Project),
+        (Tree           => (Kind => GPR2_Kind, GPR2_Value => Tree),
+         View           => (Kind => GPR2_Kind, GPR2_Value => Project),
          Default_Config => Default_Config,
          File_Configs   => File_Configs);
    end Extract_Preprocessor_Data_From_Project;
diff --git a/extensions/src/libadalang-project_provider.adb b/extensions/src/libadalang-project_provider.adb
index 9ff32ebdf..229f440a8 100644
--- a/extensions/src/libadalang-project_provider.adb
+++ b/extensions/src/libadalang-project_provider.adb
@@ -12,8 +12,11 @@ with GNAT.Task_Lock;
 
 with GNATCOLL.Strings; use GNATCOLL.Strings;
 with GNATCOLL.VFS;     use GNATCOLL.VFS;
-with GPR2.Project.Unit_Info;
-with GPR2.Unit;
+with GPR2.Build.Compilation_Unit;
+pragma Warnings (Off, "not referenced");
+with GPR2.Build.Source.Sets;
+pragma Warnings (On, "not referenced");
+with GPR2.Log;
 
 with Libadalang.GPR_Utils;      use Libadalang.GPR_Utils;
 with Libadalang.Implementation; use Libadalang.Implementation;
@@ -42,7 +45,7 @@ package body Libadalang.Project_Provider is
             GPR1_Env              : Prj.Project_Environment_Access;
             GPR1_Is_Project_Owner : Boolean;
          when GPR2_Kind =>
-            GPR2_Tree : access GPR2.Project.Tree.Object;
+            GPR2_Tree : GPR2.Project.Tree.Object;
       end case;
    end record;
 
@@ -201,9 +204,15 @@ package body Libadalang.Project_Provider is
       Unit_File : constant access US.Unbounded_String :=
         (case Part is
          when Unit_Spec => FFU.Spec_File'Access,
-         when Unit_Body     => FFU.Body_File'Access);
+         when Unit_Body => FFU.Body_File'Access);
    begin
-      pragma Assert (Unit_File.all = US.Null_Unbounded_String);
+      --  TODO (eng/gpr/gpr-issues#227) Once this bug is resolved, assert that
+      --  Unit_File.all is empty.
+
+      if Unit_File.all /= US.Null_Unbounded_String then
+         return;
+      end if;
+
       Unit_File.all :=
         (if File = ""
          then US.Null_Unbounded_String
@@ -366,8 +375,7 @@ package body Libadalang.Project_Provider is
                GPR1_Is_Project_Owner => False);
 
          when GPR2_Kind =>
-            Data :=
-              (Kind => GPR2_Kind, GPR2_Tree => Tree.GPR2_Value.Reference);
+            Data := (Kind => GPR2_Kind, GPR2_Tree => Tree.GPR2_Value);
       end case;
       Provider.Projects := Views;
       return LAL.Create_Unit_Provider_Reference (Provider);
@@ -498,6 +506,16 @@ package body Libadalang.Project_Provider is
          Trace.Decrease_Indent;
       end if;
 
+      --  For GPR2, make sure that all projects are namespace roots
+
+      if Tree.Kind = GPR2_Kind then
+         for Item of Partition loop
+            for P of Item.Projects loop
+               pragma Assert (P.GPR2_Value.Is_Namespace_Root);
+            end loop;
+         end loop;
+      end if;
+
       --  The partition is ready: turn each part into a unit provider and
       --  return the list.
 
@@ -570,6 +588,18 @@ package body Libadalang.Project_Provider is
             "selected project is aggregate and has more than one sub-project";
       end if;
 
+      --  Make sure we have a namespace root for GPR2, as only these can be
+      --  queried for units. If needed, take the first namespace root: all
+      --  namespace roots could do, as they all give access to the same sources
+      --  for the requested closure.
+
+      if Tree.Kind = GPR2_Kind
+         and then not Actual_View.GPR2_Value.Is_Namespace_Root
+      then
+         Actual_View.GPR2_Value :=
+           Actual_View.GPR2_Value.Namespace_Roots.First_Element;
+      end if;
+
       declare
          Views : View_Vectors.Vector;
       begin
@@ -718,78 +748,51 @@ package body Libadalang.Project_Provider is
 
       when GPR2_Kind =>
          declare
-            procedure Set (SUI : GPR2.Unit.Source_Unit_Identifier);
+            procedure Set (SUI : GPR2.Build.Compilation_Unit.Unit_Location);
             --  Set ``Filename`` and ``PLE_Root_Index`` from ``SUI``'s
 
-            function Lookup (View : GPR2.Project.View.Object) return Boolean;
-            --  If ``View`` contains the requested unit, return ``True`` and
-            --  set ``Filename`` to the corresponding filename. Return
-            --  ``False`` otherwise.
-
             Unit_Name : constant GPR2.Name_Type := GPR2.Name_Type (Str_Name);
 
             ---------
             -- Set --
             ---------
 
-            procedure Set (SUI : GPR2.Unit.Source_Unit_Identifier) is
+            procedure Set (SUI : GPR2.Build.Compilation_Unit.Unit_Location) is
                use type GPR2.Unit_Index;
             begin
                --  GPR2 sets the CU index to 0 when there is no "at N" clause
                --  in the project file. This is equivalont to "at 1", which is
                --  what we need here since PLE_Root_Index is a Positive.
 
-               Filename := US.To_Unbounded_String (SUI.Source.Value);
+               Filename := US.To_Unbounded_String (String (SUI.Source.Value));
                PLE_Root_Index :=
                  (if SUI.Index = 0 then 1 else Positive (SUI.Index));
             end Set;
-
-            ------------
-            -- Lookup --
-            ------------
-
-            function Lookup (View : GPR2.Project.View.Object) return Boolean is
-               Unit : constant GPR2.Project.Unit_Info.Object :=
-                 View.Unit (Unit_Name);
-            begin
-               if Unit.Is_Defined then
-                  case Kind is
-                     when Unit_Specification =>
-                        if Unit.Has_Spec then
-                           Set (Unit.Spec);
-                           return True;
-                        end if;
-                     when Unit_Body =>
-                        if Unit.Has_Body then
-                           Set (Unit.Main_Body);
-                           return True;
-                        end if;
-                  end case;
-               end if;
-
-               return False;
-            end Lookup;
-
-            Tree : GPR2.Project.Tree.Object renames
-              Provider.Data.GPR2_Tree.all;
          begin
-            --  Look for all the requested unit in the closure of all the
-            --  projects that this provider handles.
+            --  Look for the requested unit in all the projects that this
+            --  provider handles.
 
             for View of Provider.Projects loop
-               for V of Closure (View.GPR2_Value) loop
-                  if Lookup (V) then
-                     return;
+               declare
+                  Unit : constant GPR2.Build.Compilation_Unit.Object :=
+                    View.GPR2_Value.Unit (Unit_Name);
+               begin
+                  if Unit.Is_Defined then
+                     case Kind is
+                        when Unit_Specification =>
+                           if Unit.Has_Part (GPR2.S_Spec) then
+                              Set (Unit.Spec);
+                              return;
+                           end if;
+                        when Unit_Body =>
+                           if Unit.Has_Part (GPR2.S_Body) then
+                              Set (Unit.Main_Body);
+                              return;
+                           end if;
+                     end case;
                   end if;
-               end loop;
+               end;
             end loop;
-
-            --  Also look in the runtime project, if any
-
-            if Tree.Has_Runtime_Project and then Lookup (Tree.Runtime_Project)
-            then
-               return;
-            end if;
          end;
       end case;
 
@@ -1085,9 +1088,11 @@ package body Libadalang.Project_Provider is
             when Default =>
 
                --  Go through all projects except externally built ones
+               --  except the runtime.
 
                for V of Closure (View) loop
-                  if not V.Is_Externally_Built then
+                  if not V.Is_Externally_Built and then not V.Is_Runtime
+                  then
                      Include (V);
                   end if;
                end loop;
@@ -1104,7 +1109,10 @@ package body Libadalang.Project_Provider is
                --  Go through the whole project sub tree
 
                for V of Closure (View) loop
-                  Include (V);
+                  if Mode = Whole_Project_With_Runtime or else not V.Is_Runtime
+                  then
+                     Include (V);
+                  end if;
                end loop;
          end case;
       end Process;
@@ -1124,7 +1132,7 @@ package body Libadalang.Project_Provider is
       end Include;
 
    begin
-      --  Include sources from all the requested projects themselves
+      --  Include sources from all the requested projects
 
       if Projects.Is_Empty then
          Process (Tree.Root_Project);
@@ -1134,14 +1142,6 @@ package body Libadalang.Project_Provider is
          end loop;
       end if;
 
-      --  Only then, if requested, get runtime sources: they are common to all
-      --  subprojects.
-
-      if Mode = Whole_Project_With_Runtime and then Tree.Has_Runtime_Project
-      then
-         Include (Tree.Runtime_Project);
-      end if;
-
       --  Return the sorted list of source files. Sorting gets the output
       --  deterministic and thus helps reproducibility.
 
@@ -1150,6 +1150,46 @@ package body Libadalang.Project_Provider is
       end return;
    end Source_Files;
 
+   -----------------------
+   -- Check_Source_Info --
+   -----------------------
+
+   procedure Check_Source_Info (Tree : GPR2.Project.Tree.Object) is
+      function Is_Empty_Aggregate
+        (View : GPR2.Project.View.Object) return Boolean
+      is (View.Kind in GPR2.Aggregate_Kind and then View.Aggregated.Is_Empty);
+   begin
+      --  There is one case where it is actually expected that there is no
+      --  runtime: an aggregate project with no aggregated projects.
+
+      if not Tree.Has_Runtime_Project
+         and then not Is_Empty_Aggregate (Tree.Root_Project)
+      then
+         raise Runtime_Missing_Error;
+      end if;
+
+      if Tree.Source_Option not in GPR2.Source_Info_Option then
+         raise Source_Info_Missing_Error;
+      end if;
+   end Check_Source_Info;
+
+   --------------------
+   -- Update_Sources --
+   --------------------
+
+   function Update_Sources (Tree : GPR2.Project.Tree.Object) return Boolean is
+      Messages : GPR2.Log.Object;
+   begin
+      return Result : Boolean do
+         Tree.Update_Sources (Messages => Messages);
+         Result := not Messages.Has_Error;
+         Messages.Output_Messages
+           (Information => False,
+            Warning     => True,
+            Error       => True);
+      end return;
+   end Update_Sources;
+
    -----------------------------------
    -- Create_Project_Unit_Providers --
    -----------------------------------
@@ -1158,10 +1198,14 @@ package body Libadalang.Project_Provider is
      (Tree : GPR2.Project.Tree.Object)
       return GPR2_Provider_And_Projects_Array_Access
    is
-      Result : Any_Provider_And_Projects_Array_Access :=
-        Create_Project_Unit_Providers
-          ((Kind => GPR2_Kind, GPR2_Value => Tree.Reference));
+      Result : Any_Provider_And_Projects_Array_Access;
    begin
+      Check_Source_Info (Tree);
+
+      Result :=
+        Create_Project_Unit_Providers
+          ((Kind => GPR2_Kind, GPR2_Value => Tree));
+
       --  Convert Result (GPR library agnostic data structure) into the return
       --  type (GPR2-specific data structure).
 
@@ -1196,9 +1240,11 @@ package body Libadalang.Project_Provider is
    is
       Dummy : Project_Unit_Provider_Access;
    begin
+      Check_Source_Info (Tree);
+
       return Result : LAL.Unit_Provider_Reference do
          Create_Project_Unit_Provider
-           (Tree         => (Kind => GPR2_Kind, GPR2_Value => Tree.Reference),
+           (Tree         => (Kind => GPR2_Kind, GPR2_Value => Tree),
             View         => (Kind => GPR2_Kind, GPR2_Value => Project),
             Provider     => Dummy,
             Provider_Ref => Result);
@@ -1257,7 +1303,7 @@ package body Libadalang.Project_Provider is
       return String is
    begin
       return Default_Charset_From_Project
-        (Tree => (Kind => GPR2_Kind, GPR2_Value => Tree'Unrestricted_Access),
+        (Tree => (Kind => GPR2_Kind, GPR2_Value => Tree),
          View => (Kind => GPR2_Kind, GPR2_Value => Project));
    end Default_Charset_From_Project;
 
diff --git a/extensions/src/libadalang-project_provider.ads b/extensions/src/libadalang-project_provider.ads
index 144aaa575..ebe39916d 100644
--- a/extensions/src/libadalang-project_provider.ads
+++ b/extensions/src/libadalang-project_provider.ads
@@ -142,6 +142,32 @@ package Libadalang.Project_Provider is
    --  to allow experiments, it is totally unsupported and the API is very
    --  likely to change in the future.
 
+   Runtime_Missing_Error : exception;
+   --  Exception raised by the ``Create_Project_Unit_Provider[s]`` functions
+   --  when passed a project that does not have the runtime project loaded.
+   --
+   --  In order to load the runtime project, pass ``With_Runtime => True`` to
+   --  the relevant project loading procedure (in ``GPR2.Project.Tree``).
+
+   Source_Info_Missing_Error : exception;
+   --  Exception raised by the ``Create_Project_Unit_Provider[s]`` functions
+   --  when passed a project that does not contain the necessary source
+   --  information.
+   --
+   --  In order to load the source infomation necessary for unit providers to
+   --  work correctly, use ``GPR2.Projects.Tree.Update_Sources`` or the
+   --  ``Update_Sources`` shortcut below.
+
+   procedure Check_Source_Info (Tree : GPR2.Project.Tree.Object);
+   --  Raise ``Runtime_Missing_Error` if ``Tree`` does not have a runtime
+   --  project loaded. Raise ``Source_Missing_Info_Error`` if it does not have
+   --  source information loaded.
+
+   function Update_Sources (Tree : GPR2.Project.Tree.Object) return Boolean;
+   --  Call ``GPR2.Project.Tree.Update_Sources``, print potential
+   --  warnings/errors. Return ``True`` if there was no error, ``False``
+   --  otherwise.
+
    type GPR2_Provider_And_Projects is record
       Provider : LAL.Unit_Provider_Reference;
       Projects : GPR2.Project.View.Vector.Object;
@@ -171,9 +197,8 @@ package Libadalang.Project_Provider is
    --  providers, and it is up to callers to deallocate ``Tree`` itself.
 
    function Create_Project_Unit_Provider
-     (Tree             : GPR2.Project.Tree.Object;
-      Project          : GPR2.Project.View.Object :=
-                           GPR2.Project.View.Undefined)
+     (Tree    : GPR2.Project.Tree.Object;
+      Project : GPR2.Project.View.Object := GPR2.Project.View.Undefined)
       return LAL.Unit_Provider_Reference;
    --  Likewise, but create only one unit provider.
    --
diff --git a/testsuite/tests/ada_api/config_pragmas/projects.adb b/testsuite/tests/ada_api/config_pragmas/projects.adb
index df4d56195..d316676a4 100644
--- a/testsuite/tests/ada_api/config_pragmas/projects.adb
+++ b/testsuite/tests/ada_api/config_pragmas/projects.adb
@@ -6,15 +6,15 @@ with Ada.Text_IO;             use Ada.Text_IO;
 
 with GNATCOLL.Projects; use GNATCOLL.Projects;
 with GNATCOLL.VFS;      use GNATCOLL.VFS;
-with GPR2.Context;
-with GPR2.Path_Name;
+with GPR2.Options;
 with GPR2.Project.Tree;
 with GPR2.Project.View;
 
 with Langkit_Support.Text; use Langkit_Support.Text;
 
-with Libadalang.Analysis;       use Libadalang.Analysis;
-with Libadalang.Config_Pragmas; use Libadalang.Config_Pragmas;
+with Libadalang.Analysis;         use Libadalang.Analysis;
+with Libadalang.Config_Pragmas;   use Libadalang.Config_Pragmas;
+with Libadalang.Project_Provider; use Libadalang.Project_Provider;
 
 procedure Projects is
 
@@ -78,15 +78,17 @@ procedure Projects is
       --  Make sure we get the same mapping when loading from a GPR2 project
 
       declare
+         Options      : GPR2.Options.Object;
          Tree         : GPR2.Project.Tree.Object;
          View         : GPR2.Project.View.Object := GPR2.Project.View.Undefined;
          GPR2_Mapping : Config_Pragmas_Mapping;
       begin
-         Tree.Load_Autoconf
-           (Filename => GPR2.Path_Name.Create_File
-                          (GPR2.Filename_Type (Root_Project),
-                           GPR2.Path_Name.No_Resolution),
-            Context  => GPR2.Context.Empty);
+         Options.Add_Switch (GPR2.Options.P, Root_Project);
+         if not Tree.Load (Options, With_Runtime => True)
+            or else not Update_Sources (Tree)
+         then
+            raise Program_Error;
+         end if;
          if Project /= "" then
             for V of Tree.Ordered_Views loop
                if To_Lower (String (V.Name)) = To_Lower (Project) then
diff --git a/testsuite/tests/ada_api/gpr2_context/main.adb b/testsuite/tests/ada_api/gpr2_context/main.adb
index d6a30eeee..0d8f677ad 100644
--- a/testsuite/tests/ada_api/gpr2_context/main.adb
+++ b/testsuite/tests/ada_api/gpr2_context/main.adb
@@ -2,7 +2,7 @@ with Ada.Characters.Handling; use Ada.Characters.Handling;
 with Ada.Exceptions;          use Ada.Exceptions;
 with Ada.Text_IO;             use Ada.Text_IO;
 
-with GPR2.Context;
+with GPR2.Options;
 with GPR2.Path_Name;
 with GPR2.Project.Tree;
 with GPR2.Project.View;
@@ -38,25 +38,27 @@ procedure Main is
       With_Trivia   : Boolean := True;
       Tab_Stop      : Positive := 8)
    is
-      Tree : GPR2.Project.Tree.Object;
-      Prj  : GPR2.Project.View.Object;
-      Ctx  : Analysis_Context;
-      U    : Analysis_Unit;
-      N    : Basic_Decl;
+      Options : GPR2.Options.Object;
+      Tree    : GPR2.Project.Tree.Object;
+      Prj     : GPR2.Project.View.Object;
+      Ctx     : Analysis_Context;
+      U       : Analysis_Unit;
+      N       : Basic_Decl;
    begin
       Put_Line ("== " & Label & " ==");
       New_Line;
 
       --  Load the requested tree and fetch the requested project (if any)
 
-      Tree.Load_Autoconf
-        (Filename => GPR2.Path_Name.Create_File
-                       (GPR2.Filename_Type (Root_Project)),
-         Context  => GPR2.Context.Empty);
-      if Tree.Has_Messages then
+      Options.Add_Switch (GPR2.Options.P, Root_Project);
+      if not Tree.Load (Options) then
+         raise Program_Error;
+      elsif Tree.Has_Messages then
          Tree.Log_Messages.Output_Messages (Information => False);
       end if;
-      Tree.Update_Sources (With_Runtime => True);
+      if not Update_Sources (Tree) then
+         raise Program_Error;
+      end if;
       if Project /= "" then
          declare
             Root : constant GPR2.Project.View.Object := Tree.Root_Project;
diff --git a/testsuite/tests/ada_api/gpr2_project_partition/basic/main.adb b/testsuite/tests/ada_api/gpr2_project_partition/basic/main.adb
index 303ce2156..09ac3e151 100644
--- a/testsuite/tests/ada_api/gpr2_project_partition/basic/main.adb
+++ b/testsuite/tests/ada_api/gpr2_project_partition/basic/main.adb
@@ -4,8 +4,7 @@
 with Ada.Text_IO; use Ada.Text_IO;
 
 with GNATCOLL.Traces;
-with GPR2.Context;
-with GPR2.Path_Name;
+with GPR2.Options;
 with GPR2.Project.Tree;
 
 with Libadalang.Analysis;         use Libadalang.Analysis;
@@ -19,15 +18,19 @@ procedure Main is
 
    type Context_Array is array (Positive range <>) of Analysis_Context;
 
-   Tree : GPR2.Project.Tree.Object;
-   PAPs : GPR2_Provider_And_Projects_Array_Access;
+   Options : GPR2.Options.Object;
+   Tree    : GPR2.Project.Tree.Object;
+   PAPs    : GPR2_Provider_And_Projects_Array_Access;
 
 begin
    GNATCOLL.Traces.Parse_Config ("LIBADALANG.PROJECT_PROVIDER=yes");
    Put_Line ("Loading the project:");
-   Tree.Load_Autoconf
-     (Filename => GPR2.Path_Name.Create_File ("ap1.gpr"),
-      Context  => GPR2.Context.Empty);
+   Options.Add_Switch (GPR2.Options.P, "ap1.gpr");
+   if not Tree.Load (Options, With_Runtime => True)
+      or else not Update_Sources (Tree)
+   then
+      raise Program_Error;
+   end if;
    PAPs := Create_Project_Unit_Providers (Tree);
 
    declare
diff --git a/testsuite/tests/ada_api/gpr2_project_partition/c_units/main.adb b/testsuite/tests/ada_api/gpr2_project_partition/c_units/main.adb
index fcde2aff7..3fe5583e0 100644
--- a/testsuite/tests/ada_api/gpr2_project_partition/c_units/main.adb
+++ b/testsuite/tests/ada_api/gpr2_project_partition/c_units/main.adb
@@ -2,20 +2,23 @@
 
 with Ada.Text_IO; use Ada.Text_IO;
 
-with GPR2.Context;
-with GPR2.Path_Name;
+with GPR2.Options;
 with GPR2.Project.Tree;
 
 with Libadalang.Project_Provider; use Libadalang.Project_Provider;
 
 procedure Main is
-   Tree : GPR2.Project.Tree.Object;
-   PAPs : GPR2_Provider_And_Projects_Array_Access;
+   Options : GPR2.Options.Object;
+   Tree    : GPR2.Project.Tree.Object;
+   PAPs    : GPR2_Provider_And_Projects_Array_Access;
 begin
    Put_Line ("Loading the project:");
-   Tree.Load_Autoconf
-     (Filename => GPR2.Path_Name.Create_File ("ap.gpr"),
-      Context  => GPR2.Context.Empty);
+   Options.Add_Switch (GPR2.Options.P, "ap.gpr");
+   if not Tree.Load (Options, With_Runtime => True)
+      or else not Update_Sources (Tree)
+   then
+      raise Program_Error;
+   end if;
    PAPs := Create_Project_Unit_Providers (Tree);
    for I in PAPs'Range loop
       Put ("  *");
diff --git a/testsuite/tests/ada_api/gpr2_project_partition/empty/main.adb b/testsuite/tests/ada_api/gpr2_project_partition/empty/main.adb
index 22cb2ee9e..b552f7823 100644
--- a/testsuite/tests/ada_api/gpr2_project_partition/empty/main.adb
+++ b/testsuite/tests/ada_api/gpr2_project_partition/empty/main.adb
@@ -2,20 +2,23 @@
 
 with Ada.Text_IO; use Ada.Text_IO;
 
-with GPR2.Context;
-with GPR2.Path_Name;
+with GPR2.Options;
 with GPR2.Project.Tree;
 
 with Libadalang.Project_Provider; use Libadalang.Project_Provider;
 
 procedure Main is
-   Tree : GPR2.Project.Tree.Object;
-   PAPs : GPR2_Provider_And_Projects_Array_Access;
+   Options : GPR2.Options.Object;
+   Tree    : GPR2.Project.Tree.Object;
+   PAPs    : GPR2_Provider_And_Projects_Array_Access;
 begin
    Put_Line ("Loading the project:");
-   Tree.Load_Autoconf
-     (Filename => GPR2.Path_Name.Create_File ("ap.gpr"),
-      Context  => GPR2.Context.Empty);
+   Options.Add_Switch (GPR2.Options.P, "ap.gpr");
+   if not Tree.Load (Options, With_Runtime => True)
+      or else not Update_Sources (Tree)
+   then
+      raise Program_Error;
+   end if;
    PAPs := Create_Project_Unit_Providers (Tree);
    for I in PAPs'Range loop
       Put ("  *");
diff --git a/testsuite/tests/ada_api/gpr2_project_partition/empty/test.out b/testsuite/tests/ada_api/gpr2_project_partition/empty/test.out
index 03720c467..bad8cd19a 100644
--- a/testsuite/tests/ada_api/gpr2_project_partition/empty/test.out
+++ b/testsuite/tests/ada_api/gpr2_project_partition/empty/test.out
@@ -1,3 +1,4 @@
 Loading the project:
+ap.gpr: warning: no language for the projects tree: configuration skipped
   *
 Done.
diff --git a/testsuite/tests/ada_api/gpr2_project_unit_provider/main.adb b/testsuite/tests/ada_api/gpr2_project_unit_provider/main.adb
index 8e8b43d1d..247fa8292 100644
--- a/testsuite/tests/ada_api/gpr2_project_unit_provider/main.adb
+++ b/testsuite/tests/ada_api/gpr2_project_unit_provider/main.adb
@@ -6,8 +6,7 @@ with Ada.Characters.Handling; use Ada.Characters.Handling;
 with Ada.Exceptions;
 with Ada.Text_IO;             use Ada.Text_IO;
 
-with GPR2.Context;
-with GPR2.Path_Name;
+with GPR2.Options;
 with GPR2.Project.Tree;
 with GPR2.Project.View;
 
@@ -33,16 +32,19 @@ procedure Main is
    function Load_Project
      (File : String; Project : String := "") return Unit_Provider_Reference
    is
-      View : GPR2.Project.View.Object;
+      Options : GPR2.Options.Object;
+      View    : GPR2.Project.View.Object;
    begin
       Put_Line ("Loading " & File & "...");
       if Project'Length > 0 then
          Put_Line ("   Targetting subproject " & Project);
       end if;
-      Tree.Load_Autoconf
-        (Filename => GPR2.Path_Name.Create_File (GPR2.Filename_Type (File)),
-         Context  => GPR2.Context.Empty);
-      Tree.Update_Sources (With_Runtime => True);
+      Options.Add_Switch (GPR2.Options.P, File);
+      if not Tree.Load (Options, With_Runtime => True)
+         or else not Update_Sources (Tree)
+      then
+         raise Program_Error;
+      end if;
       if Project'Length > 0 then
          for V of Tree.Ordered_Views loop
             if To_Lower (String (V.Name)) = To_Lower (Project) then
diff --git a/testsuite/tests/ada_api/gpr2_project_unit_provider_invalid/main.adb b/testsuite/tests/ada_api/gpr2_project_unit_provider_invalid/main.adb
index d201128a6..4ee755ee1 100644
--- a/testsuite/tests/ada_api/gpr2_project_unit_provider_invalid/main.adb
+++ b/testsuite/tests/ada_api/gpr2_project_unit_provider_invalid/main.adb
@@ -2,8 +2,7 @@ with Ada.Exceptions;                  use Ada.Exceptions;
 with Ada.Strings.Wide_Wide_Unbounded; use Ada.Strings.Wide_Wide_Unbounded;
 with Ada.Text_IO;                     use Ada.Text_IO;
 
-with GPR2.Context;
-with GPR2.Path_Name;
+with GPR2.Options;
 with GPR2.Project.Tree;
 
 with Langkit_Support.Diagnostics; use Langkit_Support.Diagnostics;
@@ -29,10 +28,14 @@ procedure Main is
    ------------------
 
    function Load_Project (File : String) return Unit_Provider_Reference is
+      Options : GPR2.Options.Object;
    begin
-      Tree.Load_Autoconf
-        (Filename => GPR2.Path_Name.Create_File (GPR2.Filename_Type (File)),
-         Context  => GPR2.Context.Empty);
+      Options.Add_Switch (GPR2.Options.P, File);
+      if not Tree.Load (Options, With_Runtime => True)
+         or else not Update_Sources (Tree)
+      then
+         raise Program_Error;
+      end if;
       return Create_Project_Unit_Provider (Tree, Tree.Root_Project);
    end Load_Project;
 
diff --git a/testsuite/tests/ada_api/gpr_default_charset/main.adb b/testsuite/tests/ada_api/gpr_default_charset/main.adb
index bf7563814..3e68553da 100644
--- a/testsuite/tests/ada_api/gpr_default_charset/main.adb
+++ b/testsuite/tests/ada_api/gpr_default_charset/main.adb
@@ -5,8 +5,7 @@ with Ada.Text_IO; use Ada.Text_IO;
 
 with GNATCOLL.Projects; use GNATCOLL.Projects;
 with GNATCOLL.VFS;      use GNATCOLL.VFS;
-with GPR2.Context;
-with GPR2.Path_Name;
+with GPR2.Options;
 with GPR2.Project.Tree;
 
 with Libadalang.Project_Provider; use Libadalang.Project_Provider;
@@ -37,12 +36,15 @@ procedure Main is
       end;
 
       declare
-         Tree : GPR2.Project.Tree.Object;
+         Options : GPR2.Options.Object;
+         Tree    : GPR2.Project.Tree.Object;
       begin
-         Tree.Load_Autoconf
-           (Filename => GPR2.Path_Name.Create_File
-                          (GPR2.Filename_Type (project)),
-            Context  => GPR2.Context.Empty);
+         Options.Add_Switch (GPR2.Options.P, Project);
+         if not Tree.Load (Options, With_Runtime => True)
+            or else not Update_Sources (Tree)
+         then
+            raise Program_Error;
+         end if;
          Put_Line ("GPR2: " & Default_Charset_From_Project (Tree));
       end;
 
diff --git a/testsuite/tests/ada_api/source_files/main.adb b/testsuite/tests/ada_api/source_files/main.adb
index 37a8d3c82..d25f0c059 100644
--- a/testsuite/tests/ada_api/source_files/main.adb
+++ b/testsuite/tests/ada_api/source_files/main.adb
@@ -8,8 +8,8 @@ with Ada.Text_IO;             use Ada.Text_IO;
 
 with GNATCOLL.Projects; use GNATCOLL.Projects;
 with GNATCOLL.VFS;      use GNATCOLL.VFS;
-with GPR2.Context;
-with GPR2.Path_Name;
+with GPR2.Log;
+with GPR2.Options;
 with GPR2.Project.Tree;
 with GPR2.Project.View.Set;
 
@@ -24,6 +24,7 @@ procedure Main is
    Tree : Project_Tree_Access;
 
    GPR2_Tree : GPR2.Project.Tree.Object;
+   Log       : GPR2.Log.Object;
 
    type Project_Name_Array is array (Positive range <>) of Unbounded_String;
 
@@ -67,15 +68,18 @@ procedure Main is
    ----------
 
    procedure Load (Filename : String) is
+      Options : GPR2.Options.Object;
    begin
       Initialize (Env);
       Tree := new Project_Tree;
       Tree.Load (Create (+Filename), Env);
-      GPR2_Tree.Load_Autoconf
-        (Filename => GPR2.Path_Name.Create_File
-                       (GPR2.Filename_Type (Filename),
-                        GPR2.Path_Name.No_Resolution),
-         Context  => GPR2.Context.Empty);
+
+      Options.Add_Switch (GPR2.Options.P, Filename);
+      if not GPR2_Tree.Load (Options, With_Runtime => True)
+         or else not Update_Sources (GPR2_Tree)
+      then
+         raise Program_Error;
+      end if;
    end Load;
 
    ------------
@@ -134,11 +138,26 @@ procedure Main is
             use type Filename_Vectors.Vector;
 
             Has_Runtime  : Boolean := False;
-            GPR1_Sources : constant Filename_Vectors.Vector :=
+            GPR1_Sources : Filename_Vectors.Vector :=
               Source_Files (Tree.all, Mode, GPR1_Prjs);
             GPR2_Sources : constant Filename_Vectors.Vector :=
               Source_Files (GPR2_Tree, Mode, GPR2_Prjs);
          begin
+            --  Remove the "memtrack.adb" runtime unit from GPR1 sources: it is
+            --  not supposed to be there, but we have no hope to get this fixed
+            --  at this point.
+
+            for I in reverse 1 .. GPR1_Sources.Last_Index loop
+               declare
+                  Simple_Name : constant String :=
+                    Ada.Directories.Simple_Name (To_String (GPR1_Sources (I)));
+               begin
+                  if Simple_Name = "memtrack.adb" then
+                     GPR1_Sources.Delete (I);
+                  end if;
+               end;
+            end loop;
+
             for F of GPR1_Sources loop
                declare
                   Simple_Name : constant String :=
@@ -156,6 +175,14 @@ procedure Main is
             end if;
 
             if GPR1_Sources /= GPR2_Sources then
+               Put_Line ("With GPR1:");
+               for F of GPR1_Sources loop
+                  Put_Line ("  " & To_String (F));
+               end loop;
+               Put_Line ("With GPR2:");
+               for F of GPR2_Sources loop
+                  Put_Line ("  " & To_String (F));
+               end loop;
                raise Program_Error with "got different sources with GPR2";
             end if;
          end;
diff --git a/testsuite/tests/dda/project_json/main.adb b/testsuite/tests/dda/project_json/main.adb
index b18afc034..8023eec06 100644
--- a/testsuite/tests/dda/project_json/main.adb
+++ b/testsuite/tests/dda/project_json/main.adb
@@ -5,8 +5,7 @@ with Ada.Strings.Unbounded;   use Ada.Strings.Unbounded;
 with Ada.Text_IO;             use Ada.Text_IO;
 
 with GNATCOLL.Traces;
-with GPR2.Context;
-with GPR2.Path_Name;
+with GPR2.Options;
 with GPR2.Project.Tree;
 with GPR2.Project.View;
 
@@ -18,18 +17,17 @@ with Libadalang.Project_Provider;   use Libadalang.Project_Provider;
 
 procedure Main is
 
-   Ctx     : Analysis_Context;
-   Tree    : GPR2.Project.Tree.Object;
-   View    : GPR2.Project.View.Object;
    Repinfo : Repinfo_Collection;
 
    function "+"
      (S : String) return Unbounded_String renames To_Unbounded_String;
 
    procedure Load_Project
-     (Filename   : String;
-      Var_Name   : GPR2.Optional_Name_Type := "";
-      Var_Value  : GPR2.Value_Type := "";
+     (Tree       : in out GPR2.Project.Tree.Object;
+      View       : out GPR2.Project.View.Object;
+      Filename   : String;
+      Var_Name   : String := "";
+      Var_Value  : String := "";
       Subdirs    : String := "";
       Subproject : String := "");
    --  Load in ``Tree`` the project file ``Filename` with the given settings
@@ -39,7 +37,10 @@ procedure Main is
    --  Set ``View`` to ``Undefined`` if ``Subproject`` is the empty string, and
    --  to the view with the corresponding name otherwise.
 
-   procedure Check (Sources : Filename_Array);
+   procedure Check
+     (Tree    : GPR2.Project.Tree.Object;
+      View    : GPR2.Project.View.Object;
+      Sources : Filename_Array);
    --  Load all Ada sources files denoted by the filenames in ``Sources`` and
    --  lookup type information for the (only expected) type declaration they
    --  contain.
@@ -49,24 +50,32 @@ procedure Main is
    ------------------
 
    procedure Load_Project
-     (Filename   : String;
-      Var_Name   : GPR2.Optional_Name_Type := "";
-      Var_Value  : GPR2.Value_Type := "";
+     (Tree       : in out GPR2.Project.Tree.Object;
+      View       : out GPR2.Project.View.Object;
+      Filename   : String;
+      Var_Name   : String := "";
+      Var_Value  : String := "";
       Subdirs    : String := "";
       Subproject : String := "")
    is
-      Context : GPR2.Context.Object;
+      Options : GPR2.Options.Object;
    begin
+      Options.Add_Switch (GPR2.Options.P, Filename);
+      if Subdirs /= "" then
+         Options.Add_Switch (GPR2.Options.Subdirs, Subdirs);
+      end if;
       if Var_Name'Length > 0 then
-         Context.Insert (Var_Name, Var_Value);
+         Options.Add_Switch (GPR2.Options.X, Var_Name & "=" & Var_Value);
       end if;
 
-      Tree.Load_Autoconf
-        (Filename => GPR2.Path_Name.Create_File
-                       (Name      => GPR2.Filename_Type (Filename),
-                        Directory => GPR2.Path_Name.No_Resolution),
-         Context  => Context,
-         Subdirs  => GPR2.Optional_Name_Type (Subdirs));
+      if not Tree.Load
+               (Options,
+                With_Runtime     => True,
+                Absent_Dir_Error => GPR2.No_Error)
+         or else not Update_Sources (Tree)
+      then
+         raise Program_Error;
+      end if;
 
       View := GPR2.Project.View.Undefined;
       if Subproject'Length > 0 then
@@ -80,16 +89,19 @@ procedure Main is
               "cannot find " & Subproject & " in " & Filename;
          end if;
       end if;
-
-      Ctx := Create_Context
-        (Unit_Provider => Create_Project_Unit_Provider (Tree, View));
    end Load_Project;
 
    -----------
    -- Check --
    -----------
 
-   procedure Check (Sources : Filename_Array) is
+   procedure Check
+     (Tree    : GPR2.Project.Tree.Object;
+      View    : GPR2.Project.View.Object;
+      Sources : Filename_Array)
+   is
+      Ctx    : constant Analysis_Context := Create_Context
+        (Unit_Provider => Create_Project_Unit_Provider (Tree, View));
       U      : Analysis_Unit;
       T      : Base_Type_Decl;
       T_Info : Type_Representation;
@@ -126,9 +138,14 @@ begin
 
    Put_Line ("== Simple ==");
    New_Line;
-   Load_Project ("simple.gpr");
-   Repinfo := Load_From_Project (Tree, View);
-   Check ((1 => +"src/simple/simple.ads"));
+   declare
+      Tree : GPR2.Project.Tree.Object;
+      View : GPR2.Project.View.Object;
+   begin
+      Load_Project (Tree, View, "simple.gpr");
+      Repinfo := Load_From_Project (Tree, View);
+      Check (Tree, View, (1 => +"src/simple/simple.ads"));
+   end;
    New_Line;
 
    --  Make sure Load_From_Project honors its View formal: it is not supposed
@@ -136,11 +153,18 @@ begin
 
    Put_Line ("== Tree ==");
    New_Line;
-   Load_Project ("tree_root.gpr", Subproject => "tree_child");
-   Repinfo := Load_From_Project (Tree, View);
-   Check
-     ((+"src/tree_root/tree_root.ads",
-       +"src/tree_child/tree_child.ads"));
+   declare
+      Tree : GPR2.Project.Tree.Object;
+      View : GPR2.Project.View.Object;
+   begin
+      Load_Project (Tree, View, "tree_root.gpr", Subproject => "tree_child");
+      Repinfo := Load_From_Project (Tree, View);
+      Check
+        (Tree,
+         View,
+         (+"src/tree_root/tree_root.ads",
+          +"src/tree_child/tree_child.ads"));
+   end;
    New_Line;
 
    --  Make sure Load_From_Project correctly procesess a project loaded with
@@ -149,9 +173,14 @@ begin
 
    Put_Line ("== Subdirs ==");
    New_Line;
-   Load_Project ("simple.gpr", Subdirs => "somesubdirs");
-   Repinfo := Load_From_Project (Tree, View, Subdirs => "othersubdirs");
-   Check ((1 => +"src/simple/simple.ads"));
+   declare
+      Tree : GPR2.Project.Tree.Object;
+      View : GPR2.Project.View.Object;
+   begin
+      Load_Project (Tree, View, "simple.gpr", Subdirs => "somesubdirs");
+      Repinfo := Load_From_Project (Tree, View, Subdirs => "othersubdirs");
+      Check (Tree, View, (1 => +"src/simple/simple.ads"));
+   end;
    New_Line;
 
    --  Make sure Load_From_Project passes expected external variables to
@@ -160,9 +189,15 @@ begin
 
    Put_Line ("== With vars ==");
    New_Line;
-   Load_Project ("with_var.gpr", Var_Name => "MY_VAR", Var_Value => "foo");
-   Repinfo := Load_From_Project (Tree, View);
-   Check ((1 => +"src/with_var/with_var.ads"));
+   declare
+      Tree : GPR2.Project.Tree.Object;
+      View : GPR2.Project.View.Object;
+   begin
+      Load_Project
+        (Tree, View, "with_var.gpr", Var_Name => "MY_VAR", Var_Value => "foo");
+      Repinfo := Load_From_Project (Tree, View);
+      Check (Tree, View, (1 => +"src/with_var/with_var.ads"));
+   end;
    New_Line;
 
    Put_Line ("Done.");
diff --git a/testsuite/tests/prep/errors/main.adb b/testsuite/tests/prep/errors/main.adb
index 327a3e461..e672b475a 100644
--- a/testsuite/tests/prep/errors/main.adb
+++ b/testsuite/tests/prep/errors/main.adb
@@ -1,11 +1,10 @@
 with Ada.Text_IO; use Ada.Text_IO;
 
-with GPR2.Context;
-with GPR2.Path_Name;
+with GPR2.Options;
 with GPR2.Project.Tree;
 
-with Libadalang.Analysis;      use Libadalang.Analysis;
-with Libadalang.Preprocessing; use Libadalang.Preprocessing;
+with Libadalang.Analysis;         use Libadalang.Analysis;
+with Libadalang.Project_Provider; use Libadalang.Project_Provider;
 
 procedure Main is
 
@@ -53,12 +52,15 @@ procedure Main is
 
    --  Create a context from the example project
 
-   Tree : GPR2.Project.Tree.Object;
+   Options : GPR2.Options.Object;
+   Tree    : GPR2.Project.Tree.Object;
 begin
-   Tree.Load_Autoconf
-     (Filename => GPR2.Path_Name.Create_File
-                    ("p.gpr", GPR2.Path_Name.No_Resolution),
-      Context  => GPR2.Context.Empty);
+   Options.Add_Switch (GPR2.Options.P, "p.gpr");
+   if not Tree.Load (Options, With_Runtime => True)
+      or else not Update_Sources (Tree)
+   then
+      raise Program_Error;
+   end if;
    Ctx := Create_Context_From_Project (Tree);
 
    --  As a sanity check, first make sure that preprocessing is active
diff --git a/testsuite/tests/prep/projects/main.adb b/testsuite/tests/prep/projects/main.adb
index d27c3c1be..ac8a4387b 100644
--- a/testsuite/tests/prep/projects/main.adb
+++ b/testsuite/tests/prep/projects/main.adb
@@ -5,13 +5,14 @@ with Ada.Text_IO;             use Ada.Text_IO;
 
 with GNATCOLL.Projects; use GNATCOLL.Projects;
 with GNATCOLL.VFS;      use GNATCOLL.VFS;
-with GPR2.Context;
-with GPR2.Path_Name;
+with GPR2.Options;
 with GPR2.Project.Tree;
 with GPR2.Project.View;
 
 with Langkit_Support.Errors;   use Langkit_Support.Errors;
-with Libadalang.Preprocessing; use Libadalang.Preprocessing;
+
+with Libadalang.Preprocessing;    use Libadalang.Preprocessing;
+with Libadalang.Project_Provider; use Libadalang.Project_Provider;
 
 procedure Main is
 
@@ -35,6 +36,7 @@ procedure Main is
       Tree    : Project_Tree;
       Project : Project_Type;
 
+      Options   : GPR2.Options.Object;
       GPR2_Tree : GPR2.Project.Tree.Object;
       GPR2_View : GPR2.Project.View.Object;
    begin
@@ -46,12 +48,12 @@ procedure Main is
       Initialize (Env);
       Tree.Load (Create (+Filename));
 
-      GPR2_Tree.Load_Autoconf
-        (Filename => GPR2.Path_Name.Create_File
-                       (GPR2.Filename_Type (Filename),
-                        GPR2.Path_Name.No_Resolution),
-         Context  => GPR2.Context.Empty);
-      GPR2_Tree.Update_Sources (With_Runtime => True);
+      Options.Add_Switch (GPR2.Options.P, Filename);
+      if not GPR2_Tree.Load (Options, With_Runtime => True)
+         or else not Update_Sources (GPR2_Tree)
+      then
+         raise Program_Error;
+      end if;
 
       --  Run the extraction on all the requested subprojects