sem_ch13.adb (Adjust_Record_For_Reverse_Bit_Order): Split original Ada 95 part…

sem_ch13.adb (Adjust_Record_For_Reverse_Bit_Order): Split original Ada 95 part off into new subprogram below.

2017-01-23  Thomas Quinot  <quinot@adacore.com>

	* sem_ch13.adb (Adjust_Record_For_Reverse_Bit_Order):
	Split original Ada 95 part off into new subprogram
	below. Call that subprogram (instead of proceeding with
	AI95-0133 behaviour) if debug switch -gnatd.p is in use.
	(Adjust_Record_For_Reverse_Bit_Order_Ada_95): ... new subprogram
	* debug.adb Document new switch -gnatd.p
	* freeze.adb (Freeze_Entity.Freeze_Record_Type): Do not adjust
	record for reverse bit order if an error has already been posted
	on the record type.  This avoids generating extraneous "info:"
	messages for illegal code.

From-SVN: r244786

gcc/ada/ChangeLog

+2017-01-23  Thomas Quinot  <quinot@adacore.com>
+
+	* sem_ch13.adb (Adjust_Record_For_Reverse_Bit_Order):
+	Split original Ada 95 part off into new subprogram
+	below. Call that subprogram (instead of proceeding with
+	AI95-0133 behaviour) if debug switch -gnatd.p is in use.
+	(Adjust_Record_For_Reverse_Bit_Order_Ada_95): ... new subprogram
+	* debug.adb Document new switch -gnatd.p
+	* freeze.adb (Freeze_Entity.Freeze_Record_Type): Do not adjust
+	record for reverse bit order if an error has already been posted
+	on the record type.  This avoids generating extraneous "info:"
+	messages for illegal code.
+
 2017-01-23  Justin Squirek  <squirek@adacore.com>
 
 	* sem_ch3.adb (Analyze_Declarations): Correct comments

gcc/ada/debug.adb

@@ -106,7 +106,7 @@ package body Debug is
    --  d.m  For -gnatl, print full source only for main unit
    --  d.n  Print source file names
    --  d.o  Conservative elaboration order for indirect calls
-   --  d.p
+   --  d.p  Use original Ada 95 semantics for Bit_Order (disable AI95-0133)
    --  d.q
    --  d.r  Enable OK_To_Reorder_Components in non-variant records
    --  d.s
@@ -558,6 +558,10 @@ package body Debug is
    --  d.o  Conservative elaboration order for indirect calls. This causes
    --       P'Access to be treated as a call in more cases.
 
+   --  d.p  In Ada 95 (or 83) mode, use original Ada 95 behaviour for the
+   --       interpretation of component clauses crossing byte boundaries when
+   --       using the non-default bit order (i.e. ignore AI95-0133).
+
    --  d.r  Forces the flag OK_To_Reorder_Components to be set in all record
    --       base types that have no discriminants.
 

gcc/ada/freeze.adb

@@ -4262,10 +4262,14 @@ package body Freeze is
                  ("\??since no component clauses were specified", ADC);
 
             --  Here is where we do the processing to adjust component clauses
-            --  for reversed bit order, when not using reverse SSO.
+            --  for reversed bit order, when not using reverse SSO. If an error
+            --  has been reported on Rec already (such as SSO incompatible with
+            --  bit order), don't bother adjusting as this may generate extra
+            --  noise.
 
             elsif Reverse_Bit_Order (Rec)
               and then not Reverse_Storage_Order (Rec)
+              and then not Error_Posted (Rec)
             then
                Adjust_Record_For_Reverse_Bit_Order (Rec);
 

gcc/ada/sem_ch13.ads

@@ -50,8 +50,9 @@ package Sem_Ch13 is
 
    procedure Adjust_Record_For_Reverse_Bit_Order (R : Entity_Id);
    --  Called from Freeze where R is a record entity for which reverse bit
-   --  order is specified and there is at least one component clause. Adjusts
-   --  component positions according to either Ada 95 or Ada 2005 (AI-133).
+   --  order is specified and there is at least one component clause. Note:
+   --  component positions are normally adjusted as per AI95-0133, unless
+   --  -gnatd.p is used to restore original Ada 95 mode.
 
    procedure Check_Record_Representation_Clause (N : Node_Id);
    --  This procedure completes the analysis of a record representation clause