2016/05/04:
In the Coq backend, split the largest definitions into smaller
ones. This circumvenents a limitation of vm_compute on 32 bit
machines. This also enables us to perform sharing between
definitions, so that the generated files are much smaller.

2016/04/10:
When printing a grammar (which is done by the --only-preprocess options),
remove the leading bar '|', for compatibility with yacc and bison.

2016/03/11:
In the code back-end, generate type annotations when extracting a semantic
value out of the stack. When working with a semantic value of some function
type, OCaml would incorrectly warn that this function does not use its
argument. This warning should now be gone.

2016/03/03:
Makefile changes, so as to support ocamlbuild 4.03, which seems to have
stricter hygiene rules than previous versions.

2015/12/30:
Prevented an incorrect installation that would take place if USE_OCAMLFIND
was given during "make all" but not during "make install". Added a command
line directive --suggest-ocamlfind.

2015/11/11:
Fixed a severe bug in Menhir 20151110 which (when using the code back-end)
could cause a generated parser to crash. Thanks to ygrek for reporting the
bug.

2015/11/11:
The code produced by version XXXXXXXX of menhir --table can now be linked only
against a matching version of MenhirLib. If an incorrect version of MenhirLib
is installed, the OCaml compiler should complain that
[MenhirLib.StaticVersion.require_XXXXXXXX] is undefined.

2015/11/10:
Optimized the computation of $symbolstartpos, based on a couple of assumptions
about the lexer. (See the manual.)

2015/11/04:
Modified the treatment of %inline so that the positions that are computed are
the same, regardless of whether %inline is used. This property did not hold
until now. It now does. Of course, this means that the positions computed by
the new Menhir are not the same as those computed by older versions of Menhir.

2015/11/04:
Fixed a bug in the treatment of %inline that would lead to an incorrect
position being computed when the caller and callee had a variable by the
same name.

2015/11/04:
Modified Menhir so as to compute the start and end positions in the exact same
way as ocamlyacc. (There used to be a difference in the treatment of epsilon
productions.) Of course, this means that the positions computed by the new
Menhir are not the same as those computed by older versions of Menhir. Added
the keyword $symbolstartpos so as to simulate Parsing.symbol_start_pos()
in the ocamlyacc world. The keyword $startpos sometimes produces a position
that is too far off to the left; $symbolstartpos produces a more accurate
position.

2015/11/04:
Incompatible change of the incremental API: instead of a unit argument, the
entry points (which are named after the start symbols) now require an initial
position, which typically should be [lexbuf.lex_curr_p].

2015/11/03:
Fix-fix-and-re-fix the Makefile in an attempt to allow installation under
opam/Windows. Thanks to Daniel Weil for patient explanations and testing.

2015/10/29:
MenhirLib is now installed in both binary and source forms.
"menhir --suggest-menhirLib" reports where MenhirLib is installed.
This can be used to retrieve a snapshot of MenhirLib in source form
and include it in your project (if you wish to use --table mode, yet
do not wish to have a dependency on MenhirLib).

2015/10/26:
Allow --list-errors to work on 32-bit machines (with low hard limits).
This should fix a problem whereby the 2015/10/23 release could not
bootstrap on a 32-bit machine.

2015/10/23:
New declaration "%on_error_reduce foo", where foo is a nonterminal symbol.
This modifies the automaton as follows. In every state where a production of
the form "foo -> ..." is ready to be reduced, every error action is replaced
with a reduction of this production. (If there is a conflict between several
productions that could be reduced in this manner, nothing is done.) This does
not affect the language that is accepted by the automaton, but delays the
detection of an error: more reductions take place before the error is
detected.

2015/10/23:
Fixed a bug whereby Menhir would warn about a useless %prec declaration,
even though it was useful. This would happen when the declaration was
duplicated (by inlining or by macro-expansion) and some but not all of
the copies were useful.

2015/10/23:
Added [has_default_reduction] to the incremental API.

2015/10/23:
Modified the meaning of --canonical to allow default reductions to take
place. This implies no loss of precision in terms of lookahead sets,
and should allow gaining more contextual information when a syntax
error is encountered. (It should also lead to a smaller automaton.)

2015/10/23:
A brand new set of tools to work on syntax errors.
New command --list-errors, which produces a list of input sentences which
are representative of all possible syntax errors. (Costly.)
New command --interpret-error, which confirms that one particular input
sentence ends in a syntax error, and prints the number of the state in
which this error occurs.
New command --compile-errors, which compiles a list of erroneous sentences
(together with error messages) to OCaml code.
New command --compare-errors, which compares two lists of erroneous sentences
to check if they cover the same error states.
New command --update-errors, which updates the auto-generated comments in
a list of erroneous sentences.
New command --echo-errors, which removes all comments and messages from
a list of erroneous sentences, and echoes just the sentences.

2015/10/16:
Additions to the incremental API.
A [supplier] is a function that produces tokens on demand.
[lexer_lexbuf_to_supplier] turns a lexer and a lexbuf into a supplier.
[loop] is a ready-made made main parsing loop.
[loop_handle] is a variant that lets the user do her own error handling.
[loop_handle_undo] is a variant that additionally allows undoing the last
  few "spurious" reductions.
[number] maps a state of the LR(1) automaton to its number.

2015/10/16:
Incompatible change of the incremental API: renamed the type ['a result]
to ['a checkpoint]. This is a better name anyway, and should help avoid
confusion with the type ['a result] introduced in OCaml 4.03.

2015/10/12:
Avoid using $(shell pwd) in Makefile, for better Windows compatibility.

2015/10/05:
Fixed a bug where inconsistent OCaml code was generated when --table
and --external-tokens were used together. (Reported by Darin Morrison.)

2015/10/05:
In --infer mode, leave the .ml file around (instead of removing it) if
ocamlc fails, so we have a chance to understand what's wrong.

2015/09/21:
Re-established some error messages concerning the mis-use of $i which
had disappeared on 2015/06/29.

2015/09/11:
Fixed the mysterious message that would appear when a nonterminal symbol
begins with an uppercase letter and --infer is turned on. Clarified the
documentation to indicate that a (non-start) nonterminal symbol can begin
with an uppercase letter, but this is not recommended.

2015/08/27:
New option --inspection (added last January, documented only now). This
generates an inspection API which allows inspecting the automaton's stack,
among other things. This API can in principle be used to write custom code
for error reporting, error recovery, etc. It is not yet mature and may
change in the future.

2015/07/20:
Added the command line options --unused-token <symbol> and --unused-tokens.

2015/06/29:
Changed the treatment of the positional keywords $i. They are now
rewritten into variables of the form '_i' where 'i' is an integer.
Users are advised not to use variables of this form inside semantic
actions.

2015/02/11:
Added support for anonymous rules. This allows writing, e.g.,
list(e = expression SEMI { e })
whereas previously one should have written
list(terminated(e, SEMI)).

2015/02/09:
Moved all of the demos to ocamlbuild (instead of make).

2015/01/18:
Incompatible change of the incremental API.
The incremental API now exposes shift events too.

2015/01/16:
Fixed a couple bugs in Makefile and src/Makefile which would cause
compilation and installation to fail with "TARGET=byte". (Reported
by Jérémie Courrèges-Anglas and Daniel Dickman.)

2015/01/01:
Incompatible change of the incremental API.
The entry point main_incremental is now named Incremental.main.

2014/12/29:
Incompatible change of the incremental API.
The API now exposes reduction events.
The type 'a result is now private.
The type env is no longer parameterized.
[handle] is renamed to [resume].
[offer] and [resume] now expect a result, not an environment.

2014/12/22:
Documented the Coq back-end (designed and implemented by Jacques-Henri Jourdan).

2014/12/15:
New incremental API (in --table mode only), inspired by Frédéric Bour.

2014/12/11:
Menhir now reports an error if one of the start symbols produces
either the empty language or the singleton language {epsilon}.

Although some people out there actually define a start symbol that recognizes
{epsilon} (and use it as a way of initializing or re-initializing some global
state), this is considered bad style. Furthermore, by ruling out this case, we
are able to simplify the table back-end a little bit.

2014/12/12:
A speed improvement in the code back-end.

2014/12/08:
Menhir now requires OCaml 4.02 (instead of 3.09).

2014/12/02:
Removed support for the $previouserror keyword.
Removed support for --error-recovery mode.

2014/02/18:
In the Coq backend, use ' instead of _ as separator in identifiers.
Also, correct a serious bug that was inadvertently introduced on
2013/03/01 (r319).

2014/02/14
Lexer fix so as to support an open variant type [> ...] within
a %type<...> declaration.

2013/12/16
Updated the Makefile so that install no longer depends on all.
Updated the demos so that the lexer does not invoke "exit 0"
when encoutering eof. (This should be more intuitive.)

2013/09/11:
Fixed a newline conversion problem that would prevent Menhir from
building on Windows when using ocaml 4.01.

2013/03/02:
Switched to ocamlbuild. Many thanks to Daniel Weil for offering
very useful guidance.

2013/01/16:
"menhir --depend" was broken since someone added new whitespace in the output
of ocamldep. Fixed.

2012/12/19:
Fixed a compilation problem that would arise when a file produced
by Menhir on a 64-bit platform was compiled by ocaml on a 32-bit
platform.

2012/08/25:
Performance improvements in the computation of various information
about the automaton (module [Invariant]). The improvements will be
noticeable only for very large automata.

2012/06/07:
The option --log-grammar 3 (and above) now causes the FOLLOW sets for
*terminal* symbols to be computed and displayed.

2012/05/25:
Added the flag --canonical, which causes Menhir to produce a canonical LR(1)
automaton in the style of Knuth. This means that no merging of states takes
place during the construction of the automaton, and that no default reductions
are allowed.

2012/01/23:
Fixed a bug whereby a %nonassoc declaration was not respected. This
declaration requests that a shift/reduce conflict be reduced in favor of
neither shifting nor reducing, that is, a syntax error must occur. However,
due to an unforeseen interaction with the "default reduction" mechanism, this
declaration was sometimes ignored and reduction would take place.

2012/01/09:
Changes in the (undocumented) Coq back-end so as to match the ESOP 2012
paper.

2011/10/19:
The Makefile now tests whether Unix or Windows is used (the test is performed
by evaluating Sys.os_type under ocaml) and changes a couple settings accordingly:
- the executable file name is either menhir or menhir.exe
- the object file suffix is either .o or .obj

2011/10/19:
Added --strict, which causes many warnings about the grammar and about the
automaton to be considered errors.

2011/10/19:
The # annotations that are inserted in the generated .ml file now retain their
full path. (That is, we no longer use [Filename.basename].) This implies that
the # annotations depend on how menhir is invoked -- e.g.  "menhir
foo/bar.mly" and "cd foo && menhir bar.mly" will produce different
results. Nevertheless, this seems reasonable and useful (e.g. in conjunction
with ocamlbuild and a hierarchy of files). Thanks to Daniel Weil.

2011/10/06:
With the -lg 1 switch, Menhir now indicates whether the grammar is SLR(1).

2011/05/24:
Removed the lock in ocamldep.wrapper. It is the responsibility of the user
to avoid interferences with other processes (or other instances of the script)
that create and/or remove files.

2011/04/28:
The (internal) computation of the automaton's invariant was broken and has
been fixed. Surprisingly, this does not seem to affect the generated code,
(which was correct,) so no observable bug is fixed. Hopefully no bug is
introduced!

2011/04/07:
The grammar description files (.mly) are now read in up front and stored in
memory while they are parsed. This allows us to avoid the use of pos_in and
seek_in, which do not work correctly when CRLF conversion is being performed.

2011/04/05:
Fixed a bug in the type inference module (for parameterized non-terminals)
which would cause an infinite loop.

2011/01/24:
Fixed a bug that would cause an assertion failure in the generated parser
in some situations where the input stream was incorrect and the grammar
involved the error token. The fix might cause grammars that use the error
token to behave differently (hopefully more accurately) as of now.

2009/06/18:
Makefile changes: build and install only the bytecode version of menhirLib
when TARGET=byte is set.

2009/02/06:
Fixed ocamldep.wrapper to avoid quoting the name of the ocaml command.
This is hoped to fix a compilation problem under MinGW.

2009/02/04:
A Makefile fix to avoid a problem under Windows/Cygwin.
Renamed the ocaml-check-version script so as to avoid a warning.

2008/09/05:
Ocaml summer project: added --interpret, --table, and --suggest-*.

2008/08/06:
Fixed a problem that would cause the code inliner to abort when a semantic
value and a non-terminal symbol happened to have the same name.

2008/08/06:
Removed code sharing.

2008/06/20:
Removed an incorrect assertion that caused failures (lr1.ml, line 134).

2007/12/05:
Disabled code sharing by default, as it is currently broken. (See Yann's
message; assertion failure at runtime.)

2007/12/01:
Added an optimization to share code among states that have identical
outgoing transition tables.

2007/08/30:
Small Makefile change: create an executable file for check-ocaml-version in
order to work around the absence of dynamic loading on some platforms.

2007/05/20:
Made a fundamental change in the construction of the LR(1) automaton
in order to eliminate a bug that could lead to spurious conflicts --
thanks to Ketti for submitting a bug report.

2007/05/18:
Added --follow-construction to help understand the construction of the
LR(1) automaton (very verbose).

2007/05/11:
Code generation: more explicit qualifications with Pervasives so as
to avoid capture when the user redefines some of the built-in operators,
such as (+).
Added a new demo (calc-param) that shows how to use %parameter.

2007/03/22:
Makefile improvements (check for PREFIX; bootstrap in bytecode now
also available). Slight changes to OMakefile.shared.

2007/02/15:
Portability fix in Makefile and Makefile.shared (avoided "which").

2006/12/15:
Portability fix in Makefile.shared (replaced "&>" with "2>&1 >").

2006/06/23:
Made a slight restriction to Pager's criterion so as to never introduce
fake conflict tokens (see Lr0.compatible). This might help make conflict
explanations more accurate in the future.

2006/06/16:
Fixed bug that would cause positions to become invalid after %inlining.

2006/06/15:
Fixed --depend to be more lenient when analyzing ocamldep's output.
Added --raw-depend which transmits ocamldep's output unchanged (for
use in conjunction with omake).

2006/06/12:
Fixed bug that would cause --only-preprocess to print %token declarations
also for pseudo-tokens.
Fixed bug that caused some precedence declarations to be incorrectly
reported as useless.
Improved things so that useless pseudo-tokens now also cause warnings.
Fixed bug that would cause %type directives for terminal symbols to
be incorrectly accepted.
Fixed bug that would occur when a semantic action containing $i keywords
was %inlined.

2006/05/05:
Fixed problem that caused some end-of-stream conflicts not to be reported.
Fixed Pager's compatibility criterion to avoid creating end-of-stream conflicts.

2006/04/21:
Fixed problem that allowed generating incorrect but apparently well-typed
Objective Caml code when a semantic action was ill-typed and --infer was
omitted.

2006/03/29:
Improved conflict reports by factoring out maximal common derivation contexts.

2006/03/28:
Fixed bug that could arise when explaining a conflict in a non-LALR(1) grammar.

2006/03/27:
Changed count of reduce/reduce conflicts to allow a comparison with ocamlyacc's diagnostics.
When refusing to resolve a conflict, report all diagnostics before dying.

2006/03/18:
Added display of FOLLOW sets when using --log-grammar 2.
Added --graph option.
Fixed behavior of --depend option.

2006/01/06:
Removed reversed lists from the standard library.