Horton

Re: shadow variables - pg15 edition

David Rowley <dgrowleyml@gmail.com>

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From: David Rowley <dgrowleyml@gmail.com>
To: Justin Pryzby <pryzby@telsasoft.com>
Cc: pgsql-hackers@postgresql.org, Tomas Vondra <tomas.vondra@postgresql.org>, Peter Smith <smithpb2250@gmail.com>
Date: 2022-08-25T01:46:11Z
Lists: pgsql-hackers

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On Wed, 24 Aug 2022 at 22:47, David Rowley <dgrowleyml@gmail.com> wrote:
> 5. "Refactor" (fix the code to make it better)

> I have some ideas on how to fix the two #5s, so I'm going to go and do that now.

I've attached a patch which I think improves the code in
gistRelocateBuildBuffersOnSplit() so that there's no longer a shadowed
variable. I also benchmarked this method in a tight loop and can
measure no performance change from getting the loop index this way vs
the old way.

This only fixes one of the #5s I mentioned. I ended up scraping my
idea to fix the shadowed 'i' in get_qual_for_range() as it became too
complex.  The idea was to use list_cell_number() to find out how far
we looped in the forboth() loop.  It turned out that 'i' was used in
the subsequent loop in "j = i;". The fix just became too complex and I
didn't think it was worth the risk of breaking something just to get
rid of the showed 'i'.

David

Commits

  1. Fix shadow variable in postgres.c

  2. Add -Wshadow=compatible-local to the standard compilation flags

  3. Fix final warnings produced by -Wshadow=compatible-local

  4. Fix final compiler warning produced by -Wshadow=compatible-local

  5. Add optional parameter to PG_TRY() macros

  6. Small refactor to get rid of -Wshadow=compatible-local warning

  7. More -Wshadow=compatible-local warning fixes

  8. Further -Wshadow=compatible-local warning fixes

  9. Further reduce warnings with -Wshadow=compatible-local

  10. Reduce warnings with -Wshadow=compatible-local builds

  11. Remove shadowed local variables that are new in v15