[PATCH 0/5] glr2.cc: add support for custom error messages

[Akim Demaille]

The series of patches installs support for `%define parse.error custom`
in glr2.cc.  It has the same interface as that of lalr1.cc.  For instance
(taken from examples/c++/glr):

// Generate a custom error message.
void
yy::parser::report_syntax_error (const context& ctx) const
{
  std::cerr << ctx.location () << ": syntax error";
  if (!ctx.lookahead ().empty ())
    std::cerr << " on token " << ctx.lookahead ().name ();
  {
    enum { TOKENMAX = 10 };
    symbol_kind_type expected[TOKENMAX];
    int n = ctx.expected_tokens (expected, TOKENMAX);
    if (0 < n)
      {
        for (int i = 0; i < n; ++i)
          std::cerr << (i == 0 ? " (expected " : " or ")
                    << symbol_name (expected[i]);
        std::cerr << ')';
      }
  }
  std::cerr << '\n';
}

This was reported by Tom Shields <thomas.evans.shields@icloud.com>.
<https://lists.gnu.org/r/bug-bison/2021-08/msg00003.html>

Forthcoming changes will address the fact that currently one cannot
link two glr2.cc parsers together.

Akim Demaille (5):
  c++: avoid using the obsolete names
  c++: add move assignments to the symbol type
  glr2.cc: start the transition to using symbol_type
  glr2.cc: custom error messages
  c++: demonstrate custom error messages in the examples

 data/skeletons/c++.m4           |  57 +++-
 data/skeletons/glr2.cc          | 460 ++++++++++++++++++--------------
 data/skeletons/lalr1.cc         |   8 +-
 data/skeletons/variant.hh       |   4 +-
 examples/c++/README.md          |   9 +
 examples/c++/glr/README.md      |   3 +
 examples/c++/glr/c++-types.test |   2 +-
 examples/c++/glr/c++-types.yy   |  47 +++-
 examples/c/bistromathic/parse.y |   5 +-
 tests/c++.at                    |   5 +-
 tests/calc.at                   |   5 +
 tests/glr-regression.at         |  26 +-
 tests/local.at                  |   2 +-
 tests/types.at                  |   1 +
 14 files changed, 395 insertions(+), 239 deletions(-)

-- 
2.32.0