2007-12-06 Robert Dewar <dewar@adacore.com>

	* a-textio.adb, a-textio.ads: 
	Extensive changes to private part for wide character encoding

	* a-witeio.ads, a-witeio.adb, a-ztexio.ads, a-ztexio.adb
	(Look_Ahead): Fix mishandling of encoded sequences
	Move declaration of Wch_Con to private part (should not be visible)

	* ali.adb (Scan_ALI): Set default encoding method to brackets instead of
	UTF-8. Probably this is never used, but if it is, brackets is
	clearly correct.

	* bindgen.adb (Get_WC_Encoding): New procedure to properly handle
	setting wide character encoding for no main program case and when
	encoding is specified using -W?
	Initialize stack limit of environment task if stack limit method of
	stack checking is enabled.
	(Gen_Adainit_Ada): Use Get_WC_Encoding to output encoding method
	(Gen_Adainit_C): Use Get_WC_Encoding to output encoding method
	(Get_Main_Unit_Name): New function.
	(Gen_Adainit_Ada): Add call to main program for .NET when needed.
	(Gen_Output_File): Set Bind_Main_Program to True for .NET

	* bindusg.adb: Add line for -Wx switch

	* s-wchcon.adb, s-wchcon.ads: (Is_Start_Of_Encoding): New function
	Add comments
	Add new useful constant WC_Longest_Sequences

	* switch-b.adb: Clean up handling of -Wx switch
	For -gnatWx, set Wide_Character_Encoding_Method_Specified

	* switch-c.adb: -gnatg activates warning on assertion errors
	For -gnatWx, set Wide_Character_Encoding_Method_Specified

	* s-wchcon.adb: (Is_Start_Of_Encoding): New function



git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@130817 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 36 insertions, 11 deletions

diff --git a/gcc/ada/s-wchcon.ads b/gcc/ada/s-wchcon.ads
index 8607c19e951..af0eb7006a3 100644
--- a/gcc/ada/s-wchcon.ads
+++ b/gcc/ada/s-wchcon.ads
@@ -106,8 +106,8 @@ package System.WCh_Con is
    --  sequence ESC a b c d (five characters, where abcd are ASCII hex
    --  characters, using upper case for letters). This method is easy
    --  to deal with in external environments that do not support wide
-   --  characters, and covers the whole BMP. This is the default encoding
-   --  method.
+   --  characters, and covers the whole 16-bit BMP. Codes larger than
+   --  16#FFFF# are not representable using this encoding method.
 
    WCEM_Upper : constant WC_Encoding_Method := 2;
    --  The wide character with encoding 16#abcd#, where the upper bit is on
@@ -115,7 +115,8 @@ package System.WCh_Con is
    --  16#cd#. The second byte may never be a format control character, but
    --  is not required to be in the upper half. This method can be also used
    --  for shift-JIS or EUC where the internal coding matches the external
-   --  coding.
+   --  coding. Codes larger than 16#FFFF# are not representable using this
+   --  encoding method.
 
    WCEM_Shift_JIS : constant WC_Encoding_Method := 3;
    --  A wide character is represented by a two character sequence 16#ab#
@@ -123,19 +124,21 @@ package System.WCh_Con is
    --  as described above. The internal character code is the corresponding
    --  JIS character according to the standard algorithm for Shift-JIS
    --  conversion. See the body of package System.JIS_Conversions for
-   --  further details.
+   --  further details. Codes larger than 16#FFFF are not representable
+   --  using this encoding method.
 
    WCEM_EUC : constant WC_Encoding_Method := 4;
    --  A wide character is represented by a two character sequence 16#ab# and
    --  16#cd#, with both characters being in the upper half set. The internal
    --  character code is the corresponding JIS character according to the EUC
    --  encoding algorithm. See the body of package System.JIS_Conversions for
-   --  further details.
+   --  further details. Codes larger than 16#FFFF# are not representable using
+   --  this encoding method.
 
    WCEM_UTF8 : constant WC_Encoding_Method := 5;
-   --  An ISO 10646-1 BMP/Unicode wide character is represented in
-   --  UCS Transformation Format 8 (UTF-8) as defined in Annex R of ISO
-   --  10646-1/Am.2.  Depending on the character value, a Unicode character
+   --  An ISO 10646-1 BMP/Unicode wide character is represented in UCS
+   --  Transformation Format 8 (UTF-8), as defined in Annex R of ISO
+   --  10646-1/Am.2. Depending on the character value, a Unicode character
    --  is represented as the one to six byte sequence.
    --
    --    16#0000_0000#-16#0000_007f#: 2#0xxxxxxx#
@@ -151,7 +154,8 @@ package System.WCh_Con is
    --  where the xxx bits correspond to the left-padded bits of the
    --  16-bit character value. Note that all lower half ASCII characters
    --  are represented as ASCII bytes and all upper half characters and
-   --  other wide characters are represented as sequences of upper-half.
+   --  other wide characters are represented as sequences of upper-half. This
+   --  encoding method can represent the entire range of Wide_Wide_Character.
 
    WCEM_Brackets : constant WC_Encoding_Method := 6;
    --  A wide character is represented using one of the following sequences:
@@ -161,7 +165,10 @@ package System.WCh_Con is
    --    ["xxxxxx"]
    --    ["xxxxxxxx"]
    --
-   --  where xx are hexadecimal digits representing the character code.
+   --  where xx are hexadecimal digits representing the character code. This
+   --  encoding method can represent the entire range of Wide_Wide_Character
+   --  but in the general case results in ambiguous representations (there is
+   --  no ambiguity in Ada sources, since the above sequences are illegal Ada).
 
    WC_Encoding_Letters : constant array (WC_Encoding_Method) of Character :=
      (WCEM_Hex       => 'h',
@@ -183,10 +190,20 @@ package System.WCh_Con is
    --  Encoding methods using an upper half character (16#80#..16#FF) at
    --  the start of the sequence.
 
-   WC_Longest_Sequence : constant := 10;
+   WC_Longest_Sequence : constant := 12;
    --  The longest number of characters that can be used for a wide character
    --  or wide wide character sequence for any of the active encoding methods.
 
+   WC_Longest_Sequences : constant array (WC_Encoding_Method) of Natural :=
+     (WCEM_Hex       => 5,
+      WCEM_Upper     => 2,
+      WCEM_Shift_JIS => 2,
+      WCEM_EUC       => 2,
+      WCEM_UTF8      => 6,
+      WCEM_Brackets  => 12);
+   --  The longest number of characters that can be used for a wide character
+   --  or wide wide character sequence using the given encoding method.
+
    function Get_WC_Encoding_Method (C : Character) return WC_Encoding_Method;
    --  Given a character C, returns corresponding encoding method (see array
    --  WC_Encoding_Letters above). Raises Constraint_Error if not in list.
@@ -196,4 +213,12 @@ package System.WCh_Con is
    --  utf8, brackets, return the corresponding encoding method. Raises
    --  Constraint_Error if not in list.
 
+   function Is_Start_Of_Encoding
+     (C  : Character;
+      EM : WC_Encoding_Method) return Boolean;
+   pragma Inline (Is_Start_Of_Encoding);
+   --  Returns True if the Character C is the start of a multi-character
+   --  encoding sequence for the given encoding method EM. If EM is set to
+   --  WCEM_Brackets, this function always returns False.
+
 end System.WCh_Con;