Re: pgindent behavior we could do without

On Thu, Jul 18, 2013 at 12:27:21AM -0400, Tom Lane wrote:
> It's always annoyed me that pgindent insists on adjusting vertical
> whitespace around #else and related commands. This has, for example,
> rendered src/include/storage/barrier.h nigh illegible: you get things
> like
>
> /*
> * lwsync orders loads with respect to each other, and similarly with stores.
> * But a load can be performed before a subsequent store, so sync must be used
> * for a full memory barrier.
> */
> #define pg_memory_barrier() __asm__ __volatile__ ("sync" : : : "memory")
> #define pg_read_barrier() __asm__ __volatile__ ("lwsync" : : : "memory")
> #define pg_write_barrier() __asm__ __volatile__ ("lwsync" : : : "memory")
> #elif defined(__alpha) || defined(__alpha__) /* Alpha */
>
> which makes it look like this block of code has something to do with
> Alpha.
>
> By chance, I noticed today that this misbehavior comes from a discretely
> identifiable spot, to wit lines 289-290 in src/tools/pgindent/pgindent:
>
> # Remove blank line(s) before #else, #elif, and #endif
> $source =~ s!\n\n+(\#else|\#elif|\#endif)!\n$1!g;
>
> This seems pretty broken to me: why exactly is whitespace there such a
> bad idea? Not only that, but the next action is concerned with undoing
> some of the damage this rule causes:
>
> # Add blank line before #endif if it is the last line in the file
> $source =~ s!\n(#endif.*)\n\z!\n\n$1\n!;
>
> I assert that we should simply remove both of these bits of code, as
> just about every committer on the project is smarter about when to use
> vertical whitespace than this program is.

OK, I have developed the attached patch that shows the code change of
removing the test for #else/#elif/#endif. You will see that the new
output has odd blank lines for cases like:

#ifndef WIN32
static int copy_file(const char *fromfile, const char *tofile, bool force);
-->
#else
static int win32_pghardlink(const char *src, const char *dst);
-->
#endif

I can't think of a way to detect tight blocks like the above from cases
where there are sizable blocks, like:

#ifndef WIN32

static int copy_file(const char *fromfile, const char *tofile, bool force);
...
...
...

#else

static int win32_pghardlink(const char *src, const char *dst);
...
...
...

#endif

Ideas?

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

+ Everyone has their own god. +