[Caml-list] [ANN] New release of Menhir (20201201)

[Caml-list] [ANN] New release of Menhir (20201201)

[François Pottier]

Dear Menhir & OCaml users,

I would like to announce a new release of Menhir, the LR(1) parser generator
for OCaml. The most prominent new features are intended to improve the 
comfort
of the machinery that allows producing custom syntax error messages: a 
demo of
this machinery has been added, new library functions have been added so 
as to
make it easier to use, and the commands that deal with `.messages` files 
have
been improved. An excerpt of the changelog appears below.

   opam update
   opam upgrade menhir

Happy parsing,

--
François Pottier
francois.pottier@inria.fr
http://cambium.inria.fr/~fpottier/

## 2020/12/01

* The module `MenhirLib.ErrorReports` is extended with new functions:
   `wrap_supplier`, `extract`, `sanitize`, `compress`, `shorten`, `expand`.

* The new module `MenhirLib.LexerUtil` offers a few functions that help
   reading a file, setting up a lexing buffer, printing source code 
positions,
   etc.

* The new demo `calc-syntax-errors` demonstrates how to produce customized
   syntax error messages.

* The new command `--merge-errors` merges two `.messages` files. It can be
   useful when two or more users have independently produced partial
   `.messages` files and wish to combine their work.
   (Suggested by Gabriel Scherer and François Bobot.)

* The commands that read `.messages` files have been hardened so as to
   tolerate situations where a sentence mentions a nonexistent symbol or 
does
   not lead to an error state. When such a sentence is encountered, an error
   message is produced on the standard error channel; then, this sentence is
   ignored and processing continues. (As an exception, the command
   `--compile-errors` refuses to proceed in the presence of such sentences.)

## 2020/11/22

* The new command line switch `--dump-resolved` writes a description of the
   automaton to the file `.automaton.resolved` after all conflicts have been
   resolved and after extra reductions have been introduced. This file also
   shows which states have a default reduction.

* The command line switch `--dump` writes a description of the automaton to
   the file `.automaton` after benign conflicts have been silently resolved,
   but *before* severe conflicts are resolved and before extra 
reductions are
   introduced. (This behavior is unchanged.) The manner in which 
end-of-stream
   conflicts are displayed in this file has been improved.

* In the files `.automaton` and `.automaton.resolved`, the reduction 
table in
   each state is now presented in a much more compact and readable way.

* In the files `.automaton` and `.automaton.resolved`, the known suffix 
of the
   stack in each state is now explicitly shown. (Although it can be deduced
   from the LR(1) items, showing it helps.)

* Document the problem caused by placing a module alias declaration
   in an `.mly` file. (See *Questions and Answers* in the manual.)

* Turn off a costly internal well-formedness assertion.
   This allows a 30% speedup in the construction of large automata
   and in the conflict explanation process. (Reported by Joe.)