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yacc: restructure and fix yysyntax_error

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I would like to offer new ways to build the error message.  As a first
step, let's simplify yysyntax_error whose first loop does two things
at the same time: (i) collect the tokens to be reported in the error
message, and (ii) accumulate their sizes and possibly return
"overflow".  Let's pull (ii) in a second step.

Then test 525 (regression.at:1193: parse.error=verbose overflow)
failed.  This test checks that we correctly report "memory overflow"
when the error message is too large.  However the test is mistaken: it
is triggered in a place where there are five (large) expected tokens,
so anyway we would not display them, so there is no (memory) overflow
here!  Transform this test to (i) check that indeed there is no
overflow, and (ii) create syntax_error3 which does check the intended
behavior, but with four expected tokens.

* data/skeletons/yacc.c (yysyntax_error): First compute the list of
arguments, then compute yysize.
* tests/regression.at (parse.error=verbose overflow): Enhance and fix.
This commit is contained in:
Akim Demaille
2019-12-31 07:28:59 +01:00
parent 78bb152a63
commit f983d00e77
2 changed files with 30 additions and 24 deletions
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34
data/skeletons/yacc.c
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@@ -1184,15 +1184,12 @@ yysyntax_error (YYPTRDIFF_T *yymsg_alloc, char **yymsg,
*/
if (yytoken != YYEMPTY)
{
int yyn = yypact[+*yyssp];
YYPTRDIFF_T yysize0 = yytnamerr (YY_NULLPTR, yytname[yytoken]);
yysize = yysize0;]b4_lac_if([[
int yyn = yypact[+*yyssp];]b4_lac_if([[
YYDPRINTF ((stderr, "Constructing syntax error message\n"));]])[
yyarg[yycount++] = yytname[yytoken];
if (!yypact_value_is_default (yyn))
{]b4_lac_if([[
int yyx;
for (yyx = 0; yyx < YYNTOKENS; ++yyx)
if (yyx != YYTERROR && yyx != YYUNDEFTOK)
{
@@ -1212,7 +1209,6 @@ yysyntax_error (YYPTRDIFF_T *yymsg_alloc, char **yymsg,
int yychecklim = YYLAST - yyn + 1;
int yyxend = yychecklim < YYNTOKENS ? yychecklim : YYNTOKENS;
int yyx;
for (yyx = yyxbegin; yyx < yyxend; ++yyx)
if (yycheck[yyx + yyn] == yyx && yyx != YYTERROR
&& !yytable_value_is_error (yytable[yyx + yyn]))
@@ -1220,18 +1216,9 @@ yysyntax_error (YYPTRDIFF_T *yymsg_alloc, char **yymsg,
if (yycount == YYERROR_VERBOSE_ARGS_MAXIMUM)
{
yycount = 1;
yysize = yysize0;
break;
}
yyarg[yycount++] = yytname[yyx];
{
YYPTRDIFF_T yysize1
= yysize + yytnamerr (YY_NULLPTR, yytname[yyx]);
if (yysize <= yysize1 && yysize1 <= YYSTACK_ALLOC_MAXIMUM)
yysize = yysize1;
else
return 2;
}
}
}]b4_lac_if([[
# if ]b4_api_PREFIX[DEBUG
@@ -1256,14 +1243,19 @@ yysyntax_error (YYPTRDIFF_T *yymsg_alloc, char **yymsg,
# undef YYCASE_
}
/* Compute error message size. Don't count the "%s"s, but reserve
room for the terminator. */
yysize = (yystrlen (yyformat) - 2 * yycount) + 1;
{
/* Don't count the "%s"s in the final size, but reserve room for
the terminator. */
YYPTRDIFF_T yysize1 = yysize + (yystrlen (yyformat) - 2 * yycount) + 1;
if (yysize <= yysize1 && yysize1 <= YYSTACK_ALLOC_MAXIMUM)
yysize = yysize1;
else
return 2;
int yyi;
for (yyi = 0; yyi < yycount; ++yyi)
{
YYPTRDIFF_T yysize1 = yysize + yytnamerr (YY_NULLPTR, yyarg[yyi]);
if (yysize <= yysize1 && yysize1 <= YYSTACK_ALLOC_MAXIMUM)
yysize = yysize1;
else
return 2;
}
}
if (*yymsg_alloc < yysize)