[Ada] Fix function Prj.Env.Ada_Objects_Path

Index: prj.adb
===================================================================
--- prj.adb	(revision 207034)
+++ prj.adb	(working copy)
@@ -1105,6 +1105,7 @@ 
          Free (Project.Ada_Include_Path);
          Free (Project.Objects_Path);
          Free (Project.Ada_Objects_Path);
+         Free (Project.Ada_Objects_Path_No_Libs);
          Free_List (Project.Imported_Projects, Free_Project => False);
          Free_List (Project.All_Imported_Projects, Free_Project => False);
          Free_List (Project.Languages);
@@ -1485,7 +1486,10 @@ 
 
          if Project.Library then
             if Project.Object_Directory = No_Path_Information
-              or else Contains_ALI_Files (Project.Library_ALI_Dir.Display_Name)
+              or else
+                (Including_Libraries
+                 and then
+                 Contains_ALI_Files (Project.Library_ALI_Dir.Display_Name))
             then
                return Project.Library_ALI_Dir.Display_Name;
             else
Index: prj.ads
===================================================================
--- prj.ads	(revision 207026)
+++ prj.ads	(working copy)
@@ -973,11 +973,12 @@ 
       Only_If_Ada         : Boolean := False) return Path_Name_Type;
    --  Return the object directory to use for the project. This depends on
    --  whether we have a library project or a standard project. This function
-   --  might return No_Name when no directory applies.
-   --  If we have a library project file and Including_Libraries is True then
-   --  the library dir is returned instead of the object dir.
-   --  If Only_If_Ada is True, then No_Name will be returned when the project
-   --  doesn't Ada sources.
+   --  might return No_Name when no directory applies. If the project is a
+   --  library project file and Including_Libraries is True then the library
+   --  ALI dir is returned instead of the object dir, except when there is no
+   --  ALI files in the Library ALI dir and the object directory exists. If
+   --  Only_If_Ada is True, then No_Name is returned when the project doesn't
+   --  include any Ada source.
 
    procedure Compute_All_Imported_Projects
      (Root_Project : Project_Id;
@@ -1400,10 +1401,15 @@ 
       -------------------
 
       Ada_Objects_Path : String_Access := null;
-      --  The cached value of ADA_OBJECTS_PATH for this project file. Do not
-      --  use this field directly outside of the compiler, use
-      --  Prj.Env.Ada_Objects_Path instead.
+      --  The cached value of ADA_OBJECTS_PATH for this project file, with
+      --  library ALI directories for library projects instead of object
+      --  directories. Do not use this field directly outside of the
+      --  compiler, use Prj.Env.Ada_Objects_Path instead.
 
+      Ada_Objects_Path_No_Libs : String_Access := null;
+      --  The cached value of ADA_OBJECTS_PATH for this project file with all
+      --  object directories (no library ALI dir for library projects).
+
       Libgnarl_Needed : Yes_No_Unknown := Unknown;
       --  Set to True when libgnarl is needed to link
 
Index: prj-env.adb
===================================================================
--- prj-env.adb	(revision 207032)
+++ prj-env.adb	(working copy)
@@ -219,21 +219,37 @@ 
 
       Dummy : Boolean := False;
 
+      Result : String_Access;
+
    --  Start of processing for Ada_Objects_Path
 
    begin
       --  If it is the first time we call this function for
       --  this project, compute the objects path
 
-      if Project.Ada_Objects_Path = null then
+      if Including_Libraries and then Project.Ada_Objects_Path /= null then
+         return Project.Ada_Objects_Path;
+
+      elsif not Including_Libraries
+        and then Project.Ada_Objects_Path_No_Libs /= null
+      then
+         return Project.Ada_Objects_Path_No_Libs;
+
+      else
          Buffer := new String (1 .. 4096);
          For_All_Projects (Project, In_Tree, Dummy);
+         Result := new String'(Buffer (1 .. Buffer_Last));
+         Free (Buffer);
 
-         Project.Ada_Objects_Path := new String'(Buffer (1 .. Buffer_Last));
-         Free (Buffer);
+         if Including_Libraries then
+            Project.Ada_Objects_Path := Result;
+
+         else
+            Project.Ada_Objects_Path_No_Libs := Result;
+         end if;
+
+         return Result;
       end if;
-
-      return Project.Ada_Objects_Path;
    end Ada_Objects_Path;
 
    -------------------
Index: prj-env.ads
===================================================================
--- prj-env.ads	(revision 207026)
+++ prj-env.ads	(working copy)
@@ -90,9 +90,12 @@ 
      (Project             : Project_Id;
       In_Tree             : Project_Tree_Ref;
       Including_Libraries : Boolean := True) return String_Access;
-   --  Get the ADA_OBJECTS_PATH of a Project file. For the first call, compute
-   --  it and cache it. When Including_Libraries is False, do not include the
-   --  object directories of the library projects, and do not cache the result.
+   --  Get the ADA_OBJECTS_PATH of a Project file. For the first call with the
+   --  exact same parameters, compute it and cache it. When Including_Libraries
+   --  is False, the object directory of a library project is replaced with the
+   --  library ALI directory of this project (usually the library directory of
+   --  the project, except when attribute Library_ALI_Dir is declared) except
+   --  when the library ALI directory does not contain any ALI file.
 
    procedure Set_Ada_Paths
      (Project             : Project_Id;