Re: Possible flex-2.5.4 bug

[Manoj Srivastava <srivasta@datasync.com>]

Hi,

	On a closer look, I don't like this change in behaviour
 either. In fact, I get a worse behaviour:
----------------------------------------------------------------------
__> flex foo.l
__> gcc lex.yy.c
__> ./a.out "foo<bleh>bell"
barbell
yylex() done
*__> ./a.out "foo<bleh"
bar
error: EOF in comment
Segmentation fault
----------------------------------------------------------------------

	I _hate_ seg faults ;-). However, adding an explicit return
 makes things happier: 

----------------------------------------------------------------------
__> cat foo.l
%array

%%
"<"  { int c;
       while ( (c = input()) != '>' && c != EOF )
         ;    /* eat up text of comment */
       if ( c == EOF ) {
         printf( "\n" "error: EOF in comment\n" );
         return;
       }
     }
foo  printf("bar");
%%

void main(int argc, char **argv) {
  YY_BUFFER_STATE ybsInputBuffer;
  while(--argc) {
    ybsInputBuffer = yy_scan_string(*++argv);
    yylex();
    printf( "\n" "yylex() done\n" );
    yy_delete_buffer(ybsInputBuffer);
  }
} /* main */

int yywrap(void) {
  return 1;
} /* yywrap */
__> vi foo.l
__> flex foo.l; gcc lex.yy.c 
__> ./a.out "foo<bleh"
bar
error: EOF in comment

yylex() done
__> ./a.out "foo<bleh>bellbell"
barbellbell
yylex() done
__> ./a.out "foo<bleh>bellbell" !$
./a.out "foo<bleh>bellbell" "foo<bleh"
barbellbell
yylex() done
bar
error: EOF in comment

yylex() done
__> ./a.out "foo<bleh>bellbell" "foo<bleh" "foo<bleh>bellbell" 
barbellbell
yylex() done
bar
error: EOF in comment

yylex() done
barbellbell
yylex() done
----------------------------------------------------------------------

>>"Maarten" == Maarten Boekhold <maartenb@dutepp0.et.tudelft.nl> writes:

Maarten> But, since you have already read EOF in the scanner, and you
Maarten> have not returned from it, yylex will try to get a new
Maarten> character to continue parsing. But EOF has already appaered,
Maarten> so there's nothing in the buffer anymore. I think it's normal
Maarten> that you get an error on this. You either have to unput(EOF),
Maarten> or to 'return' from the scanner after the
Maarten> 'printf("error\n");"....

	Bingo.

	manoj
ps: I think this is a faster turn around than most support calls.
-- 
 FIELD TESTED: manufacturer lacks test equipment.
Manoj Srivastava               <url:mailto:srivasta@acm.org>
Mobile, Alabama USA            <url:http://www.datasync.com/%7Esrivasta/>


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