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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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16
data/yacc.c
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@@ -1164,6 +1164,9 @@ m4_ifdef([b4_at_dollar_used], [[ yylsp[0] = yylloc;
YYDPRINTF ((stderr, "Entering state %d\n", yystate));
if (yystate == YYFINAL)
YYACCEPT;
goto yybackup;
/*-----------.
@@ -1213,9 +1216,6 @@ yybackup:
goto yyreduce;
}
if (yyn == YYFINAL)
YYACCEPT;
/* Count tokens shifted since error; after three, turn off error
status. */
if (yyerrstatus)
@@ -1224,9 +1224,8 @@ yybackup:
/* Shift the lookahead token. */
YY_SYMBOL_PRINT ("Shifting", yytoken, &yylval, &yylloc);
/* Discard the shifted token unless it is eof. */
if (yychar != YYEOF)
yychar = YYEMPTY;
/* Discard the shifted token. */
yychar = YYEMPTY;
yystate = yyn;
*++yyvsp = yylval;
@@ -1418,9 +1417,6 @@ yyerrlab1:
YY_STACK_PRINT (yyss, yyssp);
}
if (yyn == YYFINAL)
YYACCEPT;
*++yyvsp = yylval;
]b4_locations_if([[
yyerror_range[1] = yylloc;
@@ -1461,7 +1457,7 @@ yyexhaustedlab:
#endif
yyreturn:
if (yychar != YYEOF && yychar != YYEMPTY)
if (yychar != YYEMPTY)
yydestruct ("Cleanup: discarding lookahead",
yytoken, &yylval]b4_locations_if([, &yylloc])[]b4_user_args[);
/* Do not reclaim the symbols of the rule which action triggered