This patch implements the required incompatible change in Ada 2012
that makes overlap of elementary parameters passed as OUT or IN OUT
an error (rather than a warning situation). It also implements the
debug flag -gnatd.E that converts this back to a warning.
The following program compiled in Ada 2012 mode gives:
1. with Text_IO; use Text_IO;
2. procedure OverlapWarn is
3. procedure OW (a, b : out Integer) is
4. begin
5. A := 3;
6. B := 3;
7. end;
8. X : Integer;
9. begin
10. OW (X, X);
|
>>> writable actual for "a" overlaps with actual for "b"
11. Put_Line (X'Img);
12. end OverlapWarn;
But if -gnatd.E is given in Ada 2012 mode, the error is a warning:
1. with Text_IO; use Text_IO;
2. procedure OverlapWarn is
3. procedure OW (a, b : out Integer) is
4. begin
5. A := 3;
6. B := 3;
7. end;
8. X : Integer;
9. begin
10. OW (X, X);
|
>>> warning: writable actual for "a" overlaps with actual for "b"
11. Put_Line (X'Img);
12. end OverlapWarn;
And the program can be executed, and outputs 3
Tested on x86_64-pc-linux-gnu, committed on trunk
2013-10-14 Robert Dewar <[email protected]>
* debug.adb: Document -gnatd.E.
* gnat1drv.adb (Adjust_Global_Switches): Set Error_To_Warning
if -gnatd.E set.
* opt.ads (Error_To_Warning): New switch.
* osint.adb: Minor reformatting.
* sem_warn.adb (Warn_On_Overlapping_Actuals): Overlap is error
in some cases in Ada 2012 mode (unless Error_To_Warning) is set.
* sem_warn.ads (Warn_On_Overlapping_Actuals): Document error
in Ada 2012 mode.
Index: debug.adb
===================================================================
--- debug.adb (revision 203524)
+++ debug.adb (working copy)
@@ -122,7 +122,7 @@
-- d.B
-- d.C Generate concatenation call, do not generate inline code
-- d.D SPARK strict mode
- -- d.E
+ -- d.E Turn selected errors into warnings
-- d.F SPARK mode
-- d.G Frame condition mode for gnat2why
-- d.H
@@ -581,22 +581,26 @@
-- d.w This flag turns off the scanning of loops to detect possible
-- infinite loops.
+ -- d.x No exception handlers in generated code. This causes exception
+ -- handlers to be eliminated from the generated code. They are still
+ -- fully compiled and analyzed, they just get eliminated from the
+ -- code generation step.
+
-- d.A There seems to be a problem with ASIS if we activate the circuit
-- for reading and writing the aspect specification hash table, so
-- for now, this is controlled by the debug flag d.A. The hash table
-- is only written and read if this flag is set.
- -- d.x No exception handlers in generated code. This causes exception
- -- handlers to be eliminated from the generated code. They are still
- -- fully compiled and analyzed, they just get eliminated from the
- -- code generation step.
-
-- d.C Generate call to System.Concat_n.Str_Concat_n routines in cases
-- where we would normally generate inline concatenation code.
-- d.D SPARK strict mode. Interpret compiler permissions as strictly as
-- possible in SPARK mode.
- --
+
+ -- d.E Turn selected errors into warnings. This debug switch causes a
+ -- specific set of error messages into warnings. Setting this switch
+ -- causes Opt.Error_To_Warning to be set to True.
+
-- d.F SPARK mode. Generate AST in a form suitable for formal
-- verification, as well as additional cross reference information in
-- ALI files to compute effects of subprograms. Note that ALI files
Index: gnat1drv.adb
===================================================================
--- gnat1drv.adb (revision 203521)
+++ gnat1drv.adb (working copy)
@@ -117,6 +117,13 @@
Relaxed_RM_Semantics := True;
end if;
+ -- -gnatd.E sets Error_To_Warning mode, causing selected error messages
+ -- to be treated as warnings instead of errors.
+
+ if Debug_Flag_Dot_EE then
+ Error_To_Warning := True;
+ end if;
+
-- Disable CodePeer_Mode in Check_Syntax, since we need front-end
-- expansion.
Index: sem_warn.adb
===================================================================
--- sem_warn.adb (revision 203521)
+++ sem_warn.adb (working copy)
@@ -3410,13 +3410,27 @@
then
null;
- -- Here we may need to issue message
+ -- Here we may need to issue overlap message
else
Error_Msg_Warn :=
+
+ -- Overlap checking is an error only in Ada 2012. For
+ -- earlier versions of Ada, this is a warning.
+
Ada_Version < Ada_2012
- or else not Is_Elementary_Type (Etype (Form1));
+ -- Overlap is only illegal in Ada 2012 in the case of
+ -- elementary types (passed by copy). For other types,
+ -- we always have a warning in all Ada versions.
+
+ or else not Is_Elementary_Type (Etype (Form1))
+
+ -- Finally, debug flag -gnatd.E changes the error to a
+ -- warning even in Ada 2012 mode.
+
+ or else Error_To_Warning;
+
declare
Act : Node_Id;
Form : Entity_Id;
@@ -3457,23 +3471,28 @@
then
if Act1 = First_Actual (N) then
Error_Msg_FE
- ("`IN OUT` prefix overlaps with "
- & "actual for&?I?", Act1, Form);
+ ("<`IN OUT` prefix overlaps with "
+ & "actual for&", Act1, Form);
else
-- For greater clarity, give name of formal
Error_Msg_Node_2 := Form;
Error_Msg_FE
- ("writable actual for & overlaps with "
- & "actual for&?I?", Act1, Form);
+ ("<writable actual for & overlaps with "
+ & "actual for&", Act1, Form);
end if;
else
+ -- For greater clarity, give name of formal
+
Error_Msg_Node_2 := Form;
+
+ -- This is one of the messages
+
Error_Msg_FE
- ("writable actual for & overlaps with "
- & "actual for&?I?", Act1, Form1);
+ ("<writable actual for & overlaps with "
+ & "actual for&", Act1, Form1);
end if;
end;
end if;
Index: sem_warn.ads
===================================================================
--- sem_warn.ads (revision 203521)
+++ sem_warn.ads (working copy)
@@ -6,7 +6,7 @@
-- --
-- S p e c --
-- --
--- Copyright (C) 1999-2011, Free Software Foundation, Inc. --
+-- Copyright (C) 1999-2013, 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- --
@@ -198,7 +198,9 @@
procedure Warn_On_Overlapping_Actuals (Subp : Entity_Id; N : Node_Id);
-- Called on a subprogram call. Checks whether an IN OUT actual that is
-- not by-copy may overlap with another actual, thus leading to aliasing
- -- in the body of the called subprogram.
+ -- in the body of the called subprogram. This is indeed a warning in Ada
+ -- versions prior to Ada 2012, but, unless Opt.Error_To_Warning is set by
+ -- use of debug flag -gnatd.E, this is illegal and generates an error.
procedure Warn_On_Suspicious_Index (Name : Entity_Id; X : Node_Id);
-- This is called after resolving an indexed component or a slice. Name
Index: opt.ads
===================================================================
--- opt.ads (revision 203536)
+++ opt.ads (working copy)
@@ -516,6 +516,13 @@
-- to make a single long message, and then this message is split up into
-- multiple lines not exceeding the specified length. Set by -gnatj=nn.
+ Error_To_Warning : Boolean := False;
+ -- GNAT
+ -- If True, then certain error messages (e.g. parameter overlap messages
+ -- for procedure calls in Ada 2012 mode) are treated as warnings instead
+ -- of errors. Set by debug flag -gnatd.E. A search for Error_To_Warning
+ -- will identify affected messages.
+
Exception_Handler_Encountered : Boolean := False;
-- GNAT
-- This flag is set true if the parser encounters an exception handler.
Index: osint.adb
===================================================================
--- osint.adb (revision 203521)
+++ osint.adb (working copy)
@@ -6,7 +6,7 @@
-- --
-- B o d y --
-- --
--- 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- --
@@ -1044,8 +1044,8 @@
procedure Fail (S : String) is
begin
- -- We use Output in case there is a special output set up.
- -- In this case Set_Standard_Error will have no immediate effect.
+ -- We use Output in case there is a special output set up. In this case
+ -- Set_Standard_Error will have no immediate effect.
Set_Standard_Error;
Osint.Write_Program_Name;
