build: generalize etc/prefix-gnulib-mk

[bison.git] / TODO

diff --git a/TODO b/TODO
index 216c97f4f84958ecc858ec691643720df010b76a..addd135d41d10ab571743c25074663eaaeba4d86 100644 (file)
--- a/TODO
+++ b/TODO
@@ -1,6 +1,28 @@
 -*- outline -*-
 
 * Short term
 -*- outline -*-
 
 * Short term

+** Use syntax_error from the scanner?
+This would provide a means to raise syntax error from function called
+from the scanner.  Actually, there is no good solution to report a
+lexical error in general.  Usually they are kept at the scanner level
+only, ignoring the guilty token.  But that might not be the best bet,
+since we don't benefit from the syntactic error recovery.
+
+We still have the possibility to return an invalid token number, which
+does the trick.  But then the error message from the parser is poor
+(something like "unexpected $undefined").  Since the scanner probably
+already reported the error, we should directly enter error-recovery,
+without reporting the error message (i.e., YYERROR's semantics).
+
+Back to lalr1.cc (whose name is now quite unfortunate, since it also
+covers lr and ielr), if we support exceptions from yylex, should we
+propose a lexical_error in addition to syntax_error?  Should they have
+a common root, say parse_error?  Should syntax_error be renamed
+syntactic_error for consistency with lexical_error?
+
+** Variable names.
+What should we name `variant' and `lex_symbol'?
+

 ** Use b4_symbol in all the skeleton
 Then remove the older system, including the tables generated by
 output.c
 ** Use b4_symbol in all the skeleton
 Then remove the older system, including the tables generated by
 output.c


@@ -144,11 +166,11 @@ what it should look like.  For instance what follows crashes.
 The code in yyerrlab reads:
 
       if (yychar <= YYEOF)
 The code in yyerrlab reads:
 
       if (yychar <= YYEOF)

-       {
-         /* Return failure if at end of input.  */
-         if (yychar == YYEOF)
-           YYABORT;
-       }
+        {
+          /* Return failure if at end of input.  */
+          if (yychar == YYEOF)
+            YYABORT;
+        }

 
 There are only two yychar that can be <= YYEOF: YYEMPTY and YYEOF.
 But I can't produce the situation where yychar is YYEMPTY here, is it
 
 There are only two yychar that can be <= YYEOF: YYEMPTY and YYEOF.
 But I can't produce the situation where yychar is YYEMPTY here, is it


@@ -258,7 +280,7 @@ Note that there remains the problem of locations: `@r'?
 We should find a means to provide an access to values deep in the
 stack.  For instance, instead of
 
 We should find a means to provide an access to values deep in the
 stack.  For instance, instead of
 

-       baz: qux { $$ = $<foo>-1 + $<bar>0 + $1; }
+        baz: qux { $$ = $<foo>-1 + $<bar>0 + $1; }

 
 we should be able to have:
 
 
 we should be able to have:
 


@@ -291,13 +313,13 @@ XML output for GNU Bison
 * Unit rules
 Maybe we could expand unit rules, i.e., transform
 
 * Unit rules
 Maybe we could expand unit rules, i.e., transform
 

-       exp: arith | bool;
-       arith: exp '+' exp;
-       bool: exp '&' exp;
+        exp: arith | bool;
+        arith: exp '+' exp;
+        bool: exp '&' exp;

 
 into
 
 
 into
 

-       exp: exp '+' exp | exp '&' exp;
+        exp: exp '+' exp | exp '&' exp;

 
 when there are no actions.  This can significantly speed up some
 grammars.  I can't find the papers.  In particular the book `LR
 
 when there are no actions.  This can significantly speed up some
 grammars.  I can't find the papers.  In particular the book `LR


@@ -322,19 +344,19 @@ Wow, %printer is not documented.  Clearly mark YYPRINT as obsolete.
 * Coding system independence
 Paul notes:
 
 * Coding system independence
 Paul notes:
 

-       Currently Bison assumes 8-bit bytes (i.e. that UCHAR_MAX is
-       255).  It also assumes that the 8-bit character encoding is
-       the same for the invocation of 'bison' as it is for the
-       invocation of 'cc', but this is not necessarily true when
-       people run bison on an ASCII host and then use cc on an EBCDIC
-       host.  I don't think these topics are worth our time
-       addressing (unless we find a gung-ho volunteer for EBCDIC or
-       PDP-10 ports :-) but they should probably be documented
-       somewhere.
+        Currently Bison assumes 8-bit bytes (i.e. that UCHAR_MAX is
+        255).  It also assumes that the 8-bit character encoding is
+        the same for the invocation of 'bison' as it is for the
+        invocation of 'cc', but this is not necessarily true when
+        people run bison on an ASCII host and then use cc on an EBCDIC
+        host.  I don't think these topics are worth our time
+        addressing (unless we find a gung-ho volunteer for EBCDIC or
+        PDP-10 ports :-) but they should probably be documented
+        somewhere.

 
 

-       More importantly, Bison does not currently allow NUL bytes in
-       tokens, either via escapes (e.g., "x\0y") or via a NUL byte in
-       the source code.  This should get fixed.
+        More importantly, Bison does not currently allow NUL bytes in
+        tokens, either via escapes (e.g., "x\0y") or via a NUL byte in
+        the source code.  This should get fixed.

 
 * --graph
 Show reductions.
 
 * --graph
 Show reductions.


@@ -433,10 +455,26 @@ to bison. If you're interested, I'll work on a patch.
 * Better graphics
 Equip the parser with a means to create the (visual) parse tree.
 
 * Better graphics
 Equip the parser with a means to create the (visual) parse tree.
 

+* Complaint submessage indentation.
+We already have an implementation that works fairly well for named
+reference messages, but it would be nice to use it consistently for all
+submessages from Bison.  For example, the "previous definition"
+submessage or the list of correct values for a %define variable might
+look better with indentation.
+
+However, the current implementation makes the assumption that the
+location printed on the first line is not usually much shorter than the
+locations printed on the submessage lines that follow.  That assumption
+may not hold true as often for some kinds of submessages especially if
+we ever support multiple grammar files.
+
+Here's a proposal for how a new implementation might look:
+
+  http://lists.gnu.org/archive/html/bison-patches/2009-09/msg00086.html
+

 -----
 
 -----
 

-Copyright (C) 2001, 2002, 2003, 2004, 2006, 2008-2009 Free Software
-Foundation, Inc.
+Copyright (C) 2001-2004, 2006, 2008-2012 Free Software Foundation, Inc.

 
 This file is part of Bison, the GNU Compiler Compiler.
 
 
 This file is part of Bison, the GNU Compiler Compiler.