diff --git a/gcc/ada/ChangeLog b/gcc/ada/ChangeLog
index 75806a6de23c670536d51db5d139ce765bb8797c..b98c7db1e7533115c9058f8db2c07f0abaa47aef 100644
--- a/gcc/ada/ChangeLog
+++ b/gcc/ada/ChangeLog
@@ -1,3 +1,14 @@
+2011-11-21 Robert Dewar <dewar@adacore.com>
+
+ * sem_ch3.adb: Minor reformatting.
+
+2011-11-21 Robert Dewar <dewar@adacore.com>
+
+ * s-utf_32.adb (Is_UTF_32_Line_Terminator): Recognize NEL as
+ line terminator.
+ * sinput.ads: Add section on Handling of Source Line Terminators.
+ * types.ads (Line_Terminator): Adjust comments.
+
2011-11-21 Robert Dewar <dewar@adacore.com>
* frontend.adb (Frontend): Capture restrictions from config files
diff --git a/gcc/ada/s-utf_32.adb b/gcc/ada/s-utf_32.adb
index a5af4fbc60e0eaa8bb3c6c2635a533dd8494aab0..f044b9bcc70bb2346811b5842cb0f522b2b179eb 100755
--- a/gcc/ada/s-utf_32.adb
+++ b/gcc/ada/s-utf_32.adb
@@ -6,7 +6,7 @@
-- --
-- B o d y --
-- --
--- Copyright (C) 2005-2010, Free Software Foundation, Inc. --
+-- Copyright (C) 2005-2011, 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- --
@@ -6182,6 +6182,7 @@ package body System.UTF_32 is
function Is_UTF_32_Line_Terminator (U : UTF_32) return Boolean is
begin
return U in 10 .. 13 -- Ascii.LF Ascii.VT Ascii.FF Ascii.CR
+ or else U = 16#00085# -- NEL
or else U = 16#02028# -- LINE SEPARATOR
or else U = 16#02029#; -- PARAGRAPH SEPARATOR
end Is_UTF_32_Line_Terminator;
diff --git a/gcc/ada/sem_ch3.adb b/gcc/ada/sem_ch3.adb
index 488e6dc98cc10cebf69812110b521c6131fccb1c..8aa644aea64525a4b038d7cccf0011ce2ddc119f 100644
--- a/gcc/ada/sem_ch3.adb
+++ b/gcc/ada/sem_ch3.adb
@@ -2664,8 +2664,8 @@ package body Sem_Ch3 is
-- Process expression, replacing error by integer zero, to avoid
-- cascaded errors or aborts further along in the processing
- -- Replace Error by integer zero, which seems least likely to
- -- cause cascaded errors.
+ -- Replace Error by integer zero, which seems least likely to cause
+ -- cascaded errors.
if E = Error then
Rewrite (E, Make_Integer_Literal (Sloc (E), Uint_0));
diff --git a/gcc/ada/sinput.ads b/gcc/ada/sinput.ads
index bdc268eaf0f2fd409f1e377a9f9c8a158d59d06c..1bf84af3955303b22e2963dac4c5fb90bae16142 100644
--- a/gcc/ada/sinput.ads
+++ b/gcc/ada/sinput.ads
@@ -6,7 +6,7 @@
-- --
-- S p e c --
-- --
--- Copyright (C) 1992-2010, Free Software Foundation, Inc. --
+-- Copyright (C) 1992-2011, 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- --
@@ -43,7 +43,7 @@
-- described in RM 2.2 (13). Any of the characters FF, LF, CR or VT or any
-- wide character that is a Line or Paragraph Separator acts as an end of
-- logical line in this sense, and it is essentially irrelevant whether one
--- or more appears in sequence (since if sequence of such characters is
+-- or more appears in sequence (since if a sequence of such characters is
-- regarded as separate ends of line, then the intervening logical lines
-- are null in any case).
@@ -451,6 +451,75 @@ package Sinput is
Internal_Source'Unrestricted_Access;
-- Pointer to internal source buffer
+ -----------------------------------------
+ -- Handling of Source Line Terminators --
+ -----------------------------------------
+
+ -- In this section we discuss in detail the issue of terminators used to
+ -- terminate source lines. The RM says that one or more format effectors
+ -- (other than horizontal tab) end a source line, and defines the set of
+ -- such format effectors, but does not talk about exactly how they are
+ -- represented in the source program (since in general the RM is not in
+ -- the business of specifying source program formats).
+
+ -- The type Types.Line_Terminator is defined as a subtype of Character
+ -- that includes CR/LF/VT/FF. The most common line enders in practice
+ -- are CR (some MAC systems), LF (Unix systems), and CR/LF (DOS/Windows
+ -- systems). Any of these sequences is recognized as ending a physical
+ -- source line, and if multiple such terminators appear (e.g. LF/LF),
+ -- then we consider we have an extra blank line.
+
+ -- VT and FF are recognized as terminating source lines, but they are
+ -- considered to end a logical line instead of a physical line, so that
+ -- the line numbering ignores such terminators. The use of VT and FF is
+ -- mandated by the standard, and correctly handled in a conforming manner
+ -- by GNAT, but their use is not recommended.
+
+ -- In addition to the set of characters defined by the type in Types, in
+ -- wide character encoding, then the codes returning True for a call to
+ -- System.UTF_32.Is_UTF_32_Line_Terminator are also recognized as ending
+ -- a physical source line. This includes the standard codes defined above
+ -- in addition to NEL (NEXT LINE), LINE SEPARATOR and PARAGRAPH SEPARATOR.
+ -- Again, as in the case of VT and FF, the standard requires we recognize
+ -- these as line terminators, but we consider them to be logical line
+ -- terminators. The only physical line terminators recognized are the
+ -- standard ones (CR, LF, or CR/LF).
+
+ -- However, we do not recognize the NEL (16#85#) character as having the
+ -- significance of an end of line character when operating in normal 8-bit
+ -- Latin-n input mode for the compiler. Instead the rule in this mode is
+ -- that all upper half control codes (16#80# .. 16#9F#) are illegal if they
+ -- occur in program text, and are ignored if they appear in comments.
+
+ -- First, note that this behavior is fully conforming with the standard.
+ -- The standard has nothing whatever to say about source representation
+ -- and implementations are completely free to make there own rules. In
+ -- this case, in 8-bit mode, GNAT decides that the 16#0085# character is
+ -- not a representation of the NEL character, even though it looks like it.
+ -- If you have NEL's in your program, which you expect to be treated as
+ -- end of line characters, you must use a wide character encoding such as
+ -- UTF-8 for this code to be recognized.
+
+ -- Second, an explanation of why we take this slightly surprising choice.
+ -- We have never encountered anyone actually using the NEL character to
+ -- end lines. One user raised the issue as a result of some experiments,
+ -- but no one has ever submitted a program encoded this way, in any of
+ -- the possible encodings. It seems that even when using wide character
+ -- codes extensively, the normal approach is to use standard line enders
+ -- (LF or CR/LF). So the failure to recognize NEL in this mode seems to
+ -- have no practical downside.
+
+ -- Moreover, what we have seen in a significant number of programs from
+ -- multiple sources is the practice of writing all program text in lower
+ -- half (ASCII) form, but using UTF-8 encoded wide characters freely in
+ -- comments, where the comments are terminated by normal line endings
+ -- (LF or CR/LF). The comments do not contain NEL codes, but they can and
+ -- do contain other UTF-8 encoding sequences where one of the bytes is the
+ -- NEL code. Now such programs can of course be compiled in UTF-8 mode,
+ -- but in practice they also compile fine in standard 8-bit mode without
+ -- specifying a character encoding. Since this is common practice, it would
+ -- be a signficant upwards incompatibility to recognize NEL in 8-bit mode.
+
-----------------
-- Subprograms --
-----------------
diff --git a/gcc/ada/types.ads b/gcc/ada/types.ads
index 05d3dbe1b9d8079716efaf812ca7349ef83755a3..75a910d33011a1d32683dba00afc8a80049ae63c 100644
--- a/gcc/ada/types.ads
+++ b/gcc/ada/types.ads
@@ -102,12 +102,8 @@ package Types is
-- Graphic characters, as defined in ARM
subtype Line_Terminator is Character range ASCII.LF .. ASCII.CR;
- -- Line terminator characters (LF, VT, FF, CR)
- --
- -- This definition is dubious now that we have two more wide character
- -- sequences that constitute a line terminator. Every reference to this
- -- subtype needs checking to make sure the wide character case is handled
- -- appropriately. ???
+ -- Line terminator characters (LF, VT, FF, CR). For further details,
+ -- see the extensive discussion of line termination in the Sinput spec.
subtype Upper_Half_Character is
Character range Character'Val (16#80#) .. Character'Val (16#FF#);