Horton

Re: Unused header file inclusion

Tom Lane <tgl@sss.pgh.pa.us>

View thread View on postgr.es
From: Tom Lane <tgl@sss.pgh.pa.us>
To: Alvaro Herrera <alvherre@2ndquadrant.com>
Cc: Andres Freund <andres@anarazel.de>, vignesh C <vignesh21@gmail.com>, Pg Hackers <pgsql-hackers@postgresql.org>
Date: 2019-07-31T20:55:31Z
Lists: pgsql-hackers 
Alvaro Herrera <alvherre@2ndquadrant.com> writes:
> On 2019-Jul-31, Andres Freund wrote:
>> * I think a lot of the interlinking stems from the bad idea to use
>> typedef's everywhere. In contrast to structs they cannot be forward
>> declared portably in our version of C. We should use a lot more struct
>> forward declarations, and just not use the typedef.

> I don't know about that ... I think the problem is that we both declare
> the typedef *and* define the struct in the same place.  If we were to
> split those things to separate files, the required rebuilds would be
> much less, I think, because changing a struct would no longer require
> recompiles of files that merely pass those structs around (that's very
> common for Node-derived structs).  Forward-declaring structs in
> unrelated header files just because they need them, feels a bit like
> cheating to me.

Yeah.  I seem to recall a proposal that nodes.h should contain

	typedef struct Foo Foo;

for every node type Foo, and then the other headers would just
fill in the structs, and we could get rid of a lot of ad-hoc
forward struct declarations and other hackery.

			regards, tom lane

Commits

  1. Add fmgr.h include to selfuncs.h.

  2. Add "headerscheck" script to test header-file compilability under C.

  3. Fix failure-to-compile-standalone in scripts_parallel.h.

  4. Remove fmgr.h includes from headers that don't really need it.

  5. Don't include utils/array.h from acl.h.

  6. Remove redundant prototypes for SQL callable functions.

  7. Remove unnecessary #include <limits.h>

  8. Teach tuplesort.c about "top N" sorting, in which only the first N tuples