Re: Warnings in compile

Tom Lane wrote:
> Michael Meskes <meskes(at)postgresql(dot)org> writes:
> > On Mon, May 25, 2009 at 10:19:40AM -0400, Tom Lane wrote:
> >> That sounds both dangerous and against our coding conventions. The
> >> standard way to do that is "do { ... } while (0)"
>
> > Which won't work here as the macros have continue and break commands in them.
>
> Oh, right, that was Bruce's "improvement" of the COPY code. I was less
> than thrilled with it, but didn't have an easy alternative.
>
> You can't just remove the "else", or it's unsafe; and I'm afraid that
> changing the macros into "else {}" would still leave us with some
> warnings about empty statements ...

Wow, that must have been a long time ago because I had forgotten about
it (seems it was 2005-12-27). As least I added a macro comment:

/*
* These macros centralize code used to process line_buf and raw_buf buffers.
* They are macros because they often do continue/break control and to avoid
* function call overhead in tight COPY loops.
*
* We must use "if (1)" because "do {} while(0)" overrides the continue/break
* processing. See http://www.cit.gu.edu.au/~anthony/info/C/C.macros.
*/

As I remember this was an attempt to implement Greenplum's optimizations
in a coherent manner.

I have added a comment about why "((void) 0)" is used.

--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://enterprisedb.com

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