* data/glr.c (YYERROR): Update definition.

(yyrecoverSyntaxError): Correct yyerrState logic. Correct comment.
Allow states with only a default reduction.

Fixes to avoid problem that $-N rules in GLR parsers can cause
buffer overruns, corrupting state.

* src/output.c (prepare_rules): Output max_left_semantic_context.
* src/reader.h (max_left_semantic_context): New
* src/scan-gram.l (max_left_semantic_context): Define.
(handle_action_dollar): Update max_left_semantic_context.
* data/glr.c (YYMAXLEFT): New.
(yydoAction): Increase yyrhsVals size.
(yyresolveAction): Ditto.

Fixes to problems with location handling in GLR parsers reported by
Frank Heckenbach (2003/06/05).

* data/glr.c (YYLTYPE): Make trivial if locations not used.
(YYRHSLOC): Add parentheses, make depend on whether locations used.
(YYLLOC_DEFAULT): Ditto.
(yyuserAction): Use YYLLOC_DEFAULT.
(yydoAction): Remove redundant code.

* tests/cxx-type.at: Exercise location information.
(yylex): Track locations.
(stmtMerge): Return value rather than printing.