2014-07-17 Robert Dewar <dewar@adacore.com>

	* bindgen.adb (Gen_Elab_Calls): Skip reference to elab
	entity if none exists (Gen_Elab_Calls): Complain if clash with
	No_Multiple_Elaboration.
	* s-rident.ads, restrict.ads: Add restriction No_Multiple_Elaboration.
	* sem_util.adb (Build_Elaboration_Entity): Skip building entity
	if not needed.
	* gnat_rm.texi: Document restriction No_Multiple_Elaboration.
	* sem_ch4.adb: Minor comment updates.



git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@212735 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 47 insertions, 12 deletions

diff --git a/gcc/ada/bindgen.adb b/gcc/ada/bindgen.adb
index 270aa5e07b6..a192953fbbc 100644
--- a/gcc/ada/bindgen.adb
+++ b/gcc/ada/bindgen.adb
@@ -6,7 +6,7 @@
 --                                                                          --
 --                                 B o d y                                  --
 --                                                                          --
---          Copyright (C) 1992-2013, Free Software Foundation, Inc.         --
+--          Copyright (C) 1992-2014, 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- --
@@ -1068,6 +1068,8 @@ package body Bindgen is
       Check_Elab_Flag : Boolean;
 
    begin
+      --  Loop through elaboration order entries
+
       for E in Elab_Order.First .. Elab_Order.Last loop
          declare
             Unum : constant Unit_Id := Elab_Order.Table (E);
@@ -1098,20 +1100,23 @@ package body Bindgen is
 
             --  Case of no elaboration code
 
-            --  In CodePeer mode, we special case subprogram bodies which
-            --  are handled in the 'else' part below, and lead to a call to
-            --  <subp>'Elab_Subp_Body.
-
             elsif U.No_Elab
+
+              --  In CodePeer mode, we special case subprogram bodies which
+              --  are handled in the 'else' part below, and lead to a call
+              --  to <subp>'Elab_Subp_Body.
+
               and then (not CodePeer_Mode
+
+                         --  Test for spec
+
                          or else U.Utype = Is_Spec
                          or else U.Utype = Is_Spec_Only
                          or else U.Unit_Kind /= 's')
             then
-
                --  In the case of a body with a separate spec, where the
                --  separate spec has an elaboration entity defined, this is
-               --  where we increment the elaboration entity.
+               --  where we increment the elaboration entity if one exists
 
                if U.Utype = Is_Body
                  and then Units.Table (Unum_Spec).Set_Elab_Entity
@@ -1142,8 +1147,7 @@ package body Bindgen is
                --  a spec with a body, the elaboration entity is initialized
                --  here. This is done because it's the only way to accomplish
                --  initialization of such entities, as there is no mechanism
-               --  provided for initializing global variables at load time on
-               --  AAMP.
+               --  for load time global variable initialization on AAMP.
 
                elsif AAMP_On_Target
                  and then U.Utype = Is_Spec
@@ -1179,8 +1183,7 @@ package body Bindgen is
                --  a spec with a body, the elaboration entity is initialized
                --  here. This is done because it's the only way to accomplish
                --  initialization of such entities, as there is no mechanism
-               --  provided for initializing global variables at load time on
-               --  AAMP.
+               --  for load time global variable initialization on AAMP.
 
                if AAMP_On_Target
                  and then U.Utype = Is_Spec
@@ -1192,8 +1195,39 @@ package body Bindgen is
                   Write_Statement_Buffer;
                end if;
 
+               --  Check incompatibilities with No_Multiple_Elaboration
+
+               if not CodePeer_Mode
+                 and then Cumulative_Restrictions.Set (No_Multiple_Elaboration)
+               then
+                  --  Force_Checking_Of_Elaboration_Flags (-F) not allowed
+
+                  if Force_Checking_Of_Elaboration_Flags then
+                     Osint.Fail
+                       ("-F (force elaboration checks) switch not allowed "
+                        & "with restriction No_Multiple_Elaboration active");
+
+                  --  Interfacing of libraries not allowed
+
+                  elsif Interface_Library_Unit then
+                     Osint.Fail
+                       ("binding of interfaced libraries not allowed "
+                        & "with restriction No_Multiple_Elaboration active");
+
+                  --  Non-Ada main program not allowed
+
+                  elsif not Bind_Main_Program then
+                     Osint.Fail
+                       ("non-Ada main program not allowed "
+                        & "with restriction No_Multiple_Elaboration active");
+                  end if;
+               end if;
+
+               --  OK, see if we need to test elaboration flag
+
                Check_Elab_Flag :=
-                 not CodePeer_Mode
+                 Units.Table (Unum_Spec).Set_Elab_Entity
+                   and then not CodePeer_Mode
                    and then (Force_Checking_Of_Elaboration_Flags
                               or Interface_Library_Unit
                               or not Bind_Main_Program);
@@ -1253,6 +1287,7 @@ package body Bindgen is
 
                if U.Utype /= Is_Spec
                  and then not CodePeer_Mode
+                 and then Units.Table (Unum_Spec).Set_Elab_Entity
                then
                   Set_String ("      E");
                   Set_Unit_Number (Unum_Spec);