Re: [PATCH 2/2] dtc: cpp co-existence: add support for #line directives

[Stephen Warren <swarren-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org>]

On 09/25/2012 10:34 PM, David Gibson wrote:
> On Mon, Sep 24, 2012 at 04:51:17PM -0600, Stephen Warren wrote:
>> From: Stephen Warren <swarren-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
>>
>> Line control directives of the following formats are supported:
>>     #line LINE "FILE"
>>     # LINE FILE [FLAGS]
>>
>> This allows dtc to consume the output of pre-processors, and to provide
>> error messages that refer to the original filename, including taking
>> into account any #include directives that the pre-processor may have
>> performed.
> 
> I like the idea of handling line directives, whichever way we go with
> the other cpp-related proposals.  The fact that these are
> distinguished from a propnodename beginning with # only by the
> following digits is more subtle than I'd ideally like, but I think
> it's wirth it.
> 
> The only thing I would like to see change is to only recognize line
> directives at the beginning of the line (in fact, preferably in column
> 0 only).  Unfortunately that is going to mean some mucky flex work,
> including a new start state, I expect.

That turns out to be exceedingly easy; just put ^ at the start of the
regex (after the start state specification), and Flex takes care of
everything:-)