Re: Lookahead correction for the C++ skeleton lalr1.cc

[Akim Demaille]

Hi Adrian,

There's a number of issues you should address before we install
your contribution:

- please separate the part about yacc.c
- stay within 76 columns, at most 79 occasionally
- space before parens
- use 'while (true)', not 'while (1)'
- enable all the warnings and make sure there are no errors
  when running the test suite.  See configure --enable-gcc-warnings,
  see also https://travis-ci.org/akimd/bison/builds/558164975
- to avoid clashes between identifiers, prefer yytoken to token.
- end comments with a period.
- there's a couple of useless "#if YYDEBUG" around a "YYCDEBUG"
- braces alone on their line (there is a "if (yy_lac_established_) {")
- please match the style of the git commit messages.
- I'm very afraid of your type changes in the code of yysyntax_error
  when !lac: you replaced int by yy_token_number.  I can understand
  the desire to do it, but it's too dangerous.  For instance if you
  have 256 tokens, yy_token_number is unsigned char, but yyntokens_
  is 256.  So things like

        yy_token_number yyxend = yychecklim < yyntokens_ ? yychecklim : 
yyntokens_;

  are unlikely to behave properly.
  I should probably add tests for 256 tokens in the test suite.
  Because of hidden tokens such as eof, error, etc. the change
  of type of yy_token_type is actually from 253 to 254 user tokens.
  See script below.


I have prepared the test suite for your changes.  Please see
the lac++ branch (on the official repo, and on GitHub too,
https://github.com/akimd/bison/tree/lac++).

Cheers!



$ for i in {251..255}; do
cat >input.$i.y <<EOF
%token $(for j in {0..$i}; do printf " a$j"; done)
%%
exp:
EOF
~bison/_build/9d/tests/bison -LC++ input.$i.y -o input.$i.cc 
-Dparse.error=verbose
printf $i; grep 'token_number_type;' input.$i.cc
done