Horton

Re: shadow variables - pg15 edition

David Rowley <dgrowleyml@gmail.com>

View thread View on postgr.es
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: 2022-10-05T10:22:33Z
Lists: pgsql-hackers

Attachments

On Wed, 5 Oct 2022 at 21:05, David Rowley <dgrowleyml@gmail.com> wrote:
> 5 warnings remain.  4 of these are for PG_TRY() and co.

I've attached a draft patch for a method I was considering to fix the
warnings we're getting from the nested PG_TRY() statement in
utility.c.

The C preprocessor does not allow name overloading in macros, but of
course, it does allow variable argument marcos with ...  so I just
used that and added ##__VA_ARGS__ to each variable.  I think that
should work ok providing callers only supply 0 or 1 arguments to the
macro, and of course, make that parameter value the same for each set
of macros used in the PG_TRY() statement.

The good thing about the optional argument is that we don't need to
touch any existing users of PG_TRY().  The attached just modifies the
inner-most PG_TRY() in the only nested PG_TRY() we have in the tree in
utility.c.

The only warning remaining after applying the attached is the "now"
warning in pgbench.c:7509.  I'd considered changing this to "thenow"
which translates to "right now" in the part of Scotland that I'm from.
I also considered "nownow", which is used in South Africa [1].
Anyway, I'm not really being serious, but I didn't come up with
anything better than "now2". It's just I didn't like that as it sort
of implies there are multiple definitions of "now" and I struggle with
that...  maybe I'm just thinking too much in terms of Newtonian
Relativity...

David

[1] https://www.goodthingsguy.com/fun/now-now-just-now/

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