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Clean up handling of %destructor for the end token (token 0).

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Discussed starting at
<http://lists.gnu.org/archive/html/bison-patches/2006-07/msg00019.html>
and
<http://lists.gnu.org/archive/html/help-bison/2006-07/msg00013.html>.

Make the skeletons consistent in how they pop the end token and invoke
its %destructor.
* data/glr.c (yyrecoverSyntaxError, yyparse): Don't pop the start
state, which has token number 0, since this would invoke the
%destructor for the end token.
* data/lalr1.cc (yy::parser::parse): Don't check for the final state
until after shifting the end token, or else it won't be popped.
* data/yacc.c (yyparse): Likewise.

* data/glr.c (yyparse): Clear the lookahead after shifting it even when
it's the end token.  Upon termination, destroy an unshifted lookahead
even when it's the end token.
* data/lalr1.cc (yy::parser::parse): Likewise.
* data/yacc.c (yyparse): Likewise.

* src/reader.c (packgram): Don't check rule 0.  This suppresses unused
value warnings for the end token when the user gives the end token a
%destructor.

* tests/actions.at (Printers and Destructors): Test all the above.
This commit is contained in:
Joel E. Denny
2006-07-29 04:11:33 +00:00
parent 62a9592d3d
commit 868d2d9638
6 changed files with 101 additions and 33 deletions
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6
src/reader.c
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@@ -488,7 +488,11 @@ packgram (void)
rule. Thus, the midrule actions have already been scanned in order to
set `used' flags for this rule's rhs, so grammar_rule_check will work
properly. */
grammar_rule_check (p);
/* Don't check the generated rule 0. It has no action, so some rhs
symbols may appear unused, but the parsing algorithm ensures that
%destructor's are invoked appropriately. */
if (p != grammar)
grammar_rule_check (p);
for (p = p->next; p && p->sym; p = p->next)
{