[multiple changes]

2014-01-24  Robert Dewar  <dewar@adacore.com>

	* exp_ch7.adb: Minor change of Indices to Indexes (preferred
	terminology in compiler).

2014-01-24  Robert Dewar  <dewar@adacore.com>

	* scans.ads: Remove Tok_Raise from Sterm, Eterm, After_SM
	categories, now that Ada 95 supports raise expressions.

2014-01-24  Robert Dewar  <dewar@adacore.com>

	* freeze.adb (Freeze_Enumeration_Type): Use new target parameter
	Short_Enums_On_Target.
	* sem_ch13.adb (Set_Enum_Esize): Take Short_Enums_On_Target
	into account.
	* targparm.ads, targparm.adb: Add new target parameter Short_Enums.

2014-01-24  Ed Schonberg  <schonberg@adacore.com>

	* sem_ch5.adb (Analyze_Iterator_Specification): If subtype
	indication is given explicity, check that it matches the array
	component type or the container element type of the domain
	of iteration.

2014-01-24  Tristan Gingold  <gingold@adacore.com>

	* back_end.adb (Scan_Compiler_Arguments): Set Short_Enums_On_Target.

2014-01-24  Vincent Celier  <celier@adacore.com>

	* prj-env.adb (Ada_Objects_Path): Use Ada_Objects_Path_No_Libs
	to cache the result when Including_Libraries is False.
	* prj-env.ads (Ada_Objects_Path): Update documentation
	* prj.adb (Free (Project_Id)): Also free Ada_Objects_Path_No_Libs
	(Get_Object_Directory): Return the Library_Ali_Dir only when
	when Including_Libraries is True.
	* prj.ads (Get_Object_Directory): Fix and complete documentation
	(Project_Data): New component Ada_Objects_Path_No_Libs

From-SVN: r207036

15 files changed, 193 insertions, 41 deletions

diff --git a/gcc/ada/ChangeLog b/gcc/ada/ChangeLog
index c56b138..351b9ed 100644
--- a/gcc/ada/ChangeLog
+++ b/gcc/ada/ChangeLog
@@ -1,5 +1,45 @@
 2014-01-24  Robert Dewar  <dewar@adacore.com>
 
+	* exp_ch7.adb: Minor change of Indices to Indexes (preferred
+	terminology in compiler).
+
+2014-01-24  Robert Dewar  <dewar@adacore.com>
+
+	* scans.ads: Remove Tok_Raise from Sterm, Eterm, After_SM
+	categories, now that Ada 95 supports raise expressions.
+
+2014-01-24  Robert Dewar  <dewar@adacore.com>
+
+	* freeze.adb (Freeze_Enumeration_Type): Use new target parameter
+	Short_Enums_On_Target.
+	* sem_ch13.adb (Set_Enum_Esize): Take Short_Enums_On_Target
+	into account.
+	* targparm.ads, targparm.adb: Add new target parameter Short_Enums.
+
+2014-01-24  Ed Schonberg  <schonberg@adacore.com>
+
+	* sem_ch5.adb (Analyze_Iterator_Specification): If subtype
+	indication is given explicity, check that it matches the array
+	component type or the container element type of the domain
+	of iteration.
+
+2014-01-24  Tristan Gingold  <gingold@adacore.com>
+
+	* back_end.adb (Scan_Compiler_Arguments): Set Short_Enums_On_Target.
+
+2014-01-24  Vincent Celier  <celier@adacore.com>
+
+	* prj-env.adb (Ada_Objects_Path): Use Ada_Objects_Path_No_Libs
+	to cache the result when Including_Libraries is False.
+	* prj-env.ads (Ada_Objects_Path): Update documentation
+	* prj.adb (Free (Project_Id)): Also free Ada_Objects_Path_No_Libs
+	(Get_Object_Directory): Return the Library_Ali_Dir only when
+	when Including_Libraries is True.
+	* prj.ads (Get_Object_Directory): Fix and complete documentation
+	(Project_Data): New component Ada_Objects_Path_No_Libs
+
+2014-01-24  Robert Dewar  <dewar@adacore.com>
+
 	* checks.adb (Expr_Known_Valid): Result of fpt operator never
 	considered valid.
 
diff --git a/gcc/ada/back_end.adb b/gcc/ada/back_end.adb
index c2275df..59f7bb4 100644
--- a/gcc/ada/back_end.adb
+++ b/gcc/ada/back_end.adb
@@ -40,6 +40,7 @@ with Switch;    use Switch;
 with Switch.C;  use Switch.C;
 with System;    use System;
 with Types;     use Types;
+with Targparm;
 
 with System.OS_Lib; use System.OS_Lib;
 
@@ -53,6 +54,10 @@ package body Back_End is
    pragma Import (C, flag_stack_check);
    --  Indicates if stack checking is enabled, imported from misc.c
 
+   flag_short_enums : Int;
+   pragma Import (C, flag_short_enums);
+   --  Indicates if C enumerations are packed, imported from misc.c
+
    save_argc : Nat;
    pragma Import (C, save_argc);
    --  Saved value of argc (number of arguments), imported from misc.c
@@ -262,6 +267,10 @@ package body Back_End is
 
       Opt.Stack_Checking_Enabled := (flag_stack_check /= 0);
 
+      --  Acquire short enums flag directly from GCC
+
+      Targparm.Short_Enums_On_Target := (flag_short_enums /= 0);
+
       --  Put the arguments in Args
 
       for Arg in Pos range 1 .. save_argc - 1 loop
diff --git a/gcc/ada/exp_ch7.adb b/gcc/ada/exp_ch7.adb
index 591606e..7479436 100644
--- a/gcc/ada/exp_ch7.adb
+++ b/gcc/ada/exp_ch7.adb
@@ -5157,14 +5157,14 @@ package body Exp_Ch7 is
          Exceptions_OK : constant Boolean :=
                            not Restriction_Active (No_Exception_Propagation);
 
-         procedure Build_Indices;
-         --  Generate the indices used in the dimension loops
+         procedure Build_Indexes;
+         --  Generate the indexes used in the dimension loops
 
          -------------------
-         -- Build_Indices --
+         -- Build_Indexes --
          -------------------
 
-         procedure Build_Indices is
+         procedure Build_Indexes is
          begin
             --  Generate the following identifiers:
             --    Jnn  -  for initialization
@@ -5173,14 +5173,14 @@ package body Exp_Ch7 is
                Append_To (Index_List,
                  Make_Defining_Identifier (Loc, New_External_Name ('J', Dim)));
             end loop;
-         end Build_Indices;
+         end Build_Indexes;
 
       --  Start of processing for Build_Adjust_Or_Finalize_Statements
 
       begin
          Finalizer_Decls := New_List;
 
-         Build_Indices;
+         Build_Indexes;
          Build_Object_Declarations (Finalizer_Data, Finalizer_Decls, Loc);
 
          Comp_Ref :=
@@ -5335,8 +5335,8 @@ package body Exp_Ch7 is
          function Build_Finalization_Call return Node_Id;
          --  Generate a deep finalization call for an array element
 
-         procedure Build_Indices;
-         --  Generate the initialization and finalization indices used in the
+         procedure Build_Indexes;
+         --  Generate the initialization and finalization indexes used in the
          --  dimension loops.
 
          function Build_Initialization_Call return Node_Id;
@@ -5411,10 +5411,10 @@ package body Exp_Ch7 is
          end Build_Finalization_Call;
 
          -------------------
-         -- Build_Indices --
+         -- Build_Indexes --
          -------------------
 
-         procedure Build_Indices is
+         procedure Build_Indexes is
          begin
             --  Generate the following identifiers:
             --    Jnn  -  for initialization
@@ -5427,7 +5427,7 @@ package body Exp_Ch7 is
                Append_To (Final_List,
                  Make_Defining_Identifier (Loc, New_External_Name ('F', Dim)));
             end loop;
-         end Build_Indices;
+         end Build_Indexes;
 
          -------------------------------
          -- Build_Initialization_Call --
@@ -5454,7 +5454,7 @@ package body Exp_Ch7 is
          Counter_Id := Make_Temporary (Loc, 'C');
          Finalizer_Decls := New_List;
 
-         Build_Indices;
+         Build_Indexes;
          Build_Object_Declarations (Finalizer_Data, Finalizer_Decls, Loc);
 
          --  Generate the block which houses the finalization call, the index
diff --git a/gcc/ada/freeze.adb b/gcc/ada/freeze.adb
index 952ea3f..ece601f 100644
--- a/gcc/ada/freeze.adb
+++ b/gcc/ada/freeze.adb
@@ -5275,10 +5275,16 @@ package body Freeze is
         and then not Has_Size_Clause (Typ)
         and then not Has_Size_Clause (Base_Type (Typ))
         and then Esize (Typ) < Standard_Integer_Size
+
+        --  Don't do this if Short_Enums on target
+
+        and then not Short_Enums_On_Target
       then
          Init_Esize (Typ, Standard_Integer_Size);
          Set_Alignment (Typ, Alignment (Standard_Integer));
 
+      --  Normal Ada case or size clause present or not Long_C_Enums on target
+
       else
          --  If the enumeration type interfaces to C, and it has a size clause
          --  that specifies less than int size, it warrants a warning. The
@@ -5292,6 +5298,10 @@ package body Freeze is
            and then Esize (Typ) /= Esize (Standard_Integer)
            and then not Is_Boolean_Type (Typ)
            and then not Is_Character_Type (Typ)
+
+           --  Don't do this if Short_Enums on target
+
+           and then not Short_Enums_On_Target
          then
             Error_Msg_N
               ("C enum types have the size of a C int??", Size_Clause (Typ));
diff --git a/gcc/ada/prj-env.adb b/gcc/ada/prj-env.adb
index 7943672..e6c2346 100644
--- a/gcc/ada/prj-env.adb
+++ b/gcc/ada/prj-env.adb
@@ -219,21 +219,37 @@ package body Prj.Env is
 
       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);
-
-         Project.Ada_Objects_Path := new String'(Buffer (1 .. Buffer_Last));
+         Result := new String'(Buffer (1 .. Buffer_Last));
          Free (Buffer);
-      end if;
 
-      return Project.Ada_Objects_Path;
+         if Including_Libraries then
+            Project.Ada_Objects_Path := Result;
+
+         else
+            Project.Ada_Objects_Path_No_Libs := Result;
+         end if;
+
+         return Result;
+      end if;
    end Ada_Objects_Path;
 
    -------------------
diff --git a/gcc/ada/prj-env.ads b/gcc/ada/prj-env.ads
index 39d805c..831ce8c 100644
--- a/gcc/ada/prj-env.ads
+++ b/gcc/ada/prj-env.ads
@@ -90,9 +90,12 @@ package Prj.Env is
      (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;
diff --git a/gcc/ada/prj.adb b/gcc/ada/prj.adb
index 29798a1..5768e1a 100644
--- a/gcc/ada/prj.adb
+++ b/gcc/ada/prj.adb
@@ -1105,6 +1105,7 @@ package body Prj is
          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 @@ package body Prj is
 
          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
diff --git a/gcc/ada/prj.ads b/gcc/ada/prj.ads
index 089d0c7..bcfb6d0 100644
--- a/gcc/ada/prj.ads
+++ b/gcc/ada/prj.ads
@@ -973,11 +973,12 @@ package Prj is
       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;
@@ -1400,9 +1401,14 @@ package Prj is
       -------------------
 
       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
diff --git a/gcc/ada/scans.ads b/gcc/ada/scans.ads
index c0e589d..ff05953 100644
--- a/gcc/ada/scans.ads
+++ b/gcc/ada/scans.ads
@@ -6,7 +6,7 @@
 --                                                                          --
 --                                 S p e c                                  --
 --                                                                          --
---          Copyright (C) 1992-2012, Free Software Foundation, Inc.         --
+--          Copyright (C) 1992-2013, Free Software Foundation, Inc.         --
 --                                                                          --
 -- GNAT is free software;  you can  redistribute it  and/or modify it under --
 -- terms of the  GNU General Public License as published  by the Free Soft- --
@@ -82,6 +82,15 @@ package Scans is
       Tok_Others,          -- OTHERS
       Tok_Null,            -- NULL
 
+      --  Note: Tok_Raise is in no categories now, it used to be Cterm, Eterm,
+      --  After_SM, but now that Ada 2012 has added raise expressions, the
+      --  raise token can appear anywhere. Note in particular that Tok_Raise
+      --  being in Eterm stopped the parser from recognizing "return raise
+      --  exception-name". This degrades error recovery slightly, and perhaps
+      --  we could do better, but not worth the effort.
+
+      Tok_Raise,           -- RAISE
+
       Tok_Dot,             -- .            Namext
       Tok_Apostrophe,      -- '            Namext
 
@@ -148,7 +157,6 @@ package Scans is
       Tok_Goto,            -- GOTO         Eterm, Sterm, After_SM
       Tok_If,              -- IF           Eterm, Sterm, After_SM
       Tok_Pragma,          -- PRAGMA       Eterm, Sterm, After_SM
-      Tok_Raise,           -- RAISE        Eterm, Sterm, After_SM
       Tok_Requeue,         -- REQUEUE      Eterm, Sterm, After_SM
       Tok_Return,          -- RETURN       Eterm, Sterm, After_SM
       Tok_Select,          -- SELECT       Eterm, Sterm, After_SM
diff --git a/gcc/ada/sem_attr.adb b/gcc/ada/sem_attr.adb
index f880fe6..0325287 100644
--- a/gcc/ada/sem_attr.adb
+++ b/gcc/ada/sem_attr.adb
@@ -6109,23 +6109,25 @@ package body Sem_Attr is
                         --  dimensional array.
 
                         Index_Type := First_Index (P_Type);
+
                         Index := First (Choices (Assoc));
                         while Present (Index) loop
                            if Nkind (Index) = N_Range then
-                              Analyze_And_Resolve (
-                                Low_Bound (Index), Etype (Index_Type));
-                              Analyze_And_Resolve (
-                               High_Bound (Index), Etype (Index_Type));
+                              Analyze_And_Resolve
+                                (Low_Bound (Index), Etype (Index_Type));
+                              Analyze_And_Resolve
+                                (High_Bound (Index), Etype (Index_Type));
 
                            else
                               Analyze_And_Resolve (Index, Etype (Index_Type));
                            end if;
+
                            Next (Index);
                         end loop;
 
-                     else
-                        --  Choice is a sequence of indices for each dimension
+                     --  Choice is a sequence of indexes for each dimension
 
+                     else
                         Index_Type := First_Index (P_Type);
                         Index := First (Expressions (First (Choices (Assoc))));
                         while Present (Index_Type)
@@ -6137,8 +6139,8 @@ package body Sem_Attr is
                         end loop;
 
                         if Present (Index) or else Present (Index_Type) then
-                           Error_Msg_N (
-                            "dimension mismatch in index list", Assoc);
+                           Error_Msg_N
+                             ("dimension mismatch in index list", Assoc);
                         end if;
                      end if;
                   end;
diff --git a/gcc/ada/sem_ch13.adb b/gcc/ada/sem_ch13.adb
index 9c1c698..1a0aa52 100644
--- a/gcc/ada/sem_ch13.adb
+++ b/gcc/ada/sem_ch13.adb
@@ -10790,6 +10790,10 @@ package body Sem_Ch13 is
 
       if Has_Foreign_Convention (T)
         and then Esize (T) < Standard_Integer_Size
+
+        --  Don't do this if Short_Enums on target
+
+        and then not Short_Enums_On_Target
       then
          Init_Esize (T, Standard_Integer_Size);
       else
diff --git a/gcc/ada/sem_ch3.adb b/gcc/ada/sem_ch3.adb
index da315de..c90be0c 100644
--- a/gcc/ada/sem_ch3.adb
+++ b/gcc/ada/sem_ch3.adb
@@ -9686,7 +9686,7 @@ package body Sem_Ch3 is
                then
                   --  If an inherited subprogram is implemented by a protected
                   --  procedure or an entry, then the first parameter of the
-                  --  inherited subprogram shall be of mode out or in out, or
+                  --  inherited subprogram shall be of mode OUT or IN OUT, or
                   --  an access-to-variable parameter (RM 9.4(11.9/3))
 
                   if Is_Protected_Type (Corresponding_Concurrent_Type (T))
diff --git a/gcc/ada/sem_ch5.adb b/gcc/ada/sem_ch5.adb
index 788ff89..a5be290 100644
--- a/gcc/ada/sem_ch5.adb
+++ b/gcc/ada/sem_ch5.adb
@@ -1680,12 +1680,21 @@ package body Sem_Ch5 is
 
       Ent : Entity_Id;
       Typ : Entity_Id;
+      Bas : Entity_Id;
 
    begin
       Enter_Name (Def_Id);
 
       if Present (Subt) then
          Analyze (Subt);
+
+         --  Save type of subtype indication for subsequent check.
+
+         if Nkind (Subt) = N_Subtype_Indication then
+            Bas := Entity (Subtype_Mark (Subt));
+         else
+            Bas := Entity (Subt);
+         end if;
       end if;
 
       Preanalyze_Range (Iter_Name);
@@ -1804,6 +1813,13 @@ package body Sem_Ch5 is
          if Of_Present (N) then
             Set_Etype (Def_Id, Component_Type (Typ));
 
+            if Present (Subt)
+              and then Bas /= Base_Type (Component_Type (Typ))
+            then
+               Error_Msg_N
+                 ("subtype indication does not match component type", Subt);
+            end if;
+
          --  Here we have a missing Range attribute
 
          else
@@ -1849,6 +1865,17 @@ package body Sem_Ch5 is
                else
                   Set_Etype (Def_Id, Entity (Element));
 
+                  --  If subtype indication was given, verify that it matches
+                  --  element type of container.
+
+                  if Present (Subt)
+                     and then Bas /= Base_Type (Etype (Def_Id))
+                  then
+                     Error_Msg_N
+                       ("subtype indication does not match element type",
+                          Subt);
+                  end if;
+
                   --  If the container has a variable indexing aspect, the
                   --  element is a variable and is modifiable in the loop.
 
diff --git a/gcc/ada/targparm.adb b/gcc/ada/targparm.adb
index 37ac4cd..b59f58b 100644
--- a/gcc/ada/targparm.adb
+++ b/gcc/ada/targparm.adb
@@ -63,6 +63,7 @@ package body Targparm is
       SCD,  --   Stack_Check_Default
       SCL,  --   Stack_Check_Limits
       SCP,  --   Stack_Check_Probes
+      SHE,  --   Short_Enums
       SLS,  --   Support_Long_Shifts
       SNZ,  --   Signed_Zeros
       SSL,  --   Suppress_Standard_Library
@@ -101,6 +102,7 @@ package body Targparm is
    SCD_Str : aliased constant Source_Buffer := "Stack_Check_Default";
    SCL_Str : aliased constant Source_Buffer := "Stack_Check_Limits";
    SCP_Str : aliased constant Source_Buffer := "Stack_Check_Probes";
+   SHE_Str : aliased constant Source_Buffer := "Short_Enums";
    SLS_Str : aliased constant Source_Buffer := "Support_Long_Shifts";
    SNZ_Str : aliased constant Source_Buffer := "Signed_Zeros";
    SSL_Str : aliased constant Source_Buffer := "Suppress_Standard_Library";
@@ -139,6 +141,7 @@ package body Targparm is
       SCD_Str'Access,
       SCL_Str'Access,
       SCP_Str'Access,
+      SHE_Str'Access,
       SLS_Str'Access,
       SNZ_Str'Access,
       SSL_Str'Access,
@@ -587,6 +590,7 @@ package body Targparm is
                      when EXS => Exit_Status_Supported_On_Target     := Result;
                      when FEL => Frontend_Layout_On_Target           := Result;
                      when FFO => Fractional_Fixed_Ops_On_Target      := Result;
+
                      when JVM =>
                         if Result then
                            VM_Target := JVM_Target;
@@ -608,6 +612,7 @@ package body Targparm is
                      when SCD => Stack_Check_Default_On_Target       := Result;
                      when SCL => Stack_Check_Limits_On_Target        := Result;
                      when SCP => Stack_Check_Probes_On_Target        := Result;
+                     when SHE => Short_Enums_On_Target               := Result;
                      when SLS => Support_Long_Shifts_On_Target       := Result;
                      when SSL => Suppress_Standard_Library_On_Target := Result;
                      when SNZ => Signed_Zeros_On_Target              := Result;
diff --git a/gcc/ada/targparm.ads b/gcc/ada/targparm.ads
index c3cace3..f89ebfe 100644
--- a/gcc/ada/targparm.ads
+++ b/gcc/ada/targparm.ads
@@ -197,7 +197,7 @@ package Targparm is
    ----------------------------
 
    --  The great majority of GNAT ports are based on GCC. The switches in
-   --  This section indicate the use of some non-standard target back end
+   --  this section indicate the use of some non-standard target back end
    --  or other special targetting requirements.
 
    AAMP_On_Target : Boolean := False;
@@ -605,6 +605,24 @@ package Targparm is
    Frontend_Layout_On_Target : Boolean := False;
    --  Set True if front end does layout
 
+   Short_Enums_On_Target : Boolean := False;
+   --  In most C ABI's, enumeration types always have int size. If this switch
+   --  is False, which is the default, that's what the front end implements for
+   --  enumeration types with a foreign convention (includ C and C++). However
+   --  on some ABI's (notably the ARM-EABI), enumeration types have sizes that
+   --  are minimal for the range of values. For such cases this switch is set
+   --  True (in the appropriate System file), and the front-end uses the normal
+   --  Ada rules for sizing enumeration types (which correspond to this method
+   --  of selecting the shortest signed or unsigned integer representation that
+   --  can accomodate the number of items in the type, or the range of values
+   --  if an enumeration representation clause is used.
+   --  the same size as C int, or Ada Integer. That's the most common case, but
+   --  there are targets (most notably those following the ARM-EABI) where the
+   --  size for enumeration types is the same as in Ada (i.e. the smallest
+   --  integer type that accomodates the number of enumeration choices, or the
+   --  range of values in an enumeration-representation clause). For such cases
+   --  this switch is set to False in the corresponding System file.
+
    -----------------
    -- Subprograms --
    -----------------