Re: flex 2.5.4a -- Bug?

[John W. Millaway]

--- Nikos Balkanas <address@hidden> wrote:
> Specs: Linux Suse 6.2, kernel 2.2.10, flex 2.5.4 distribution, or 2.5.4a
> compliled from source, egcs-2.91.66.
> 
> Code:
> 
> %{
> #include <stdio.h>
> #include <ctype.h>
> #include <string.h>
> 
> int lineno = 1;
> %}
> 
> space [ \t]
> sp {space}+
> ws {space}*
> newline \n
> 
> %option nounput
> %option noyymore
> %%
> 
> {newline}             { printf("Hello!\n"); }
> \n                       { printf("Wrong-->\n"); }
> .                         { ECHO; }
> 
> %%
> 
> Caveat: {newline} never expands correctly. Name of pattern doesn't matter.
> Output consists of echoed text + "Wrong->" in place of newlines. I traced it
> to the yy_accept array, which seems to be wrong. If I change the particular
> entry (from 2 to 1) and compile, I get lots of "Hello!"'s.


Flex issues a warning for the second rule, "\n", since it can never be matched.
The first rule, "{newline}" is the same as the second rule! Nevertheless, I
compiled flex version 2.5.4a and compiled the above input file, ignoring the
warning from flex. I saw the correct output, "Hello!", at the end of each line.

-John


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