ID: 26078
Updated by: [EMAIL PROTECTED]
Reported By: AxelLuttgens at swing dot be
-Status: Open
+Status: Wont fix
Bug Type: Compile Warning
Operating System: Darwin 7.0.0 (Panther)
PHP Version: 4.3.3
Previous Comments:
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[2003-11-02 07:16:47] AxelLuttgens at swing dot be
Description:
------------
I know this has already been reported, with reassuring replies such as
"that warning may be safely ignored" or "there is no need to fix this
one".
A a reminder, the message goes so:
var_unserializer.c:308: warning: comparison is always false due to
limited range of data type
(I tried with PHP 4.3.3, as well as with php4-STABLE-200311020830: same
results)
I am of the opinion that it is just lucky programming that it works
now, and that the whole matter could easily break in case of a slight
change in the code.
I don't know much about re2c, but I think I can guess how it works by
comparing the .re and the resulting .c files.
So, looking at the var_unserializer.re file, these lines seem to be the
relevant ones:
0086: #define YYCTYPE unsigned char
0097: any = [\000-\277];
0411: any { return 0; }
0415: return 0;
Corresponding lines in var_unserializer.c are:
0087: #define YYCTYPE unsigned char
0308: if(yych <= '\277') goto yy15;
0309: }
0310: }
0311: }
0312: yy2: YYCURSOR = YYMARKER;
0313: switch(yyaccept){
0314: case 0: goto yy4;
0315: }
0319: yy4:
0320: { return 0; }
0359: yy15: yych = *++YYCURSOR;
0360: goto yy4;
In the comparison, yych is promoted to an unsigned in, while (on lots
of systems) '\277' is promoted to a signed int, hence the comparison
failure.
Now, the lucky part is that yyaccept is never set in the code and thus
keeps its initialisation value (ie, zero).
So, jumping to yy15 or continuing execution through yy2 have finally
the same effect...
But the question is: shouldn't the any symbol be defined as
[\000-\377] instead of [\000-\277]?
If it is the case, I guess re2c would just forget about comparisons
with characters having decimal code greater than 127.
And one would thus alleviate spurious warnings.
If it isn't the case, well, my apologies ;-)
HTH
Axel
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Edit this bug report at http://bugs.php.net/?id=26078&edit=1
