From: Tom Lane <tgl@sss.pgh.pa.us>
To: David Rowley <dgrowleyml@gmail.com>
cc: Peter Smith <smithpb2250@gmail.com>,
        PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Subject: Re: Remove shadowed declaration warnings
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Comments: In-reply-to David Rowley <dgrowleyml@gmail.com>
	message dated "Thu, 12 Sep 2024 12:58:19 +1200"
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Date: Wed, 11 Sep 2024 22:02:59 -0400
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David Rowley <dgrowleyml@gmail.com> writes:
> On Thu, 12 Sept 2024 at 12:33, Peter Smith <smithpb2250@gmail.com> wrote:
>> I normally build the code with warnings enabled (specifically,
>> -Wshadow) which exposes many "shadowed" declarations.

> 0fe954c28 did add -Wshadow=compatible-local to the standard set of
> complication flags.  I felt it was diminishing returns after that, but
> -Wshadow=local would be the next step before going full -Wshadow.

I think that insisting that local declarations not shadow globals
is an anti-pattern, and I'll vote against any proposal to make
that a standard warning.  Impoverished as C is, it does have block
structure; why would we want to throw that away by (in effect)
demanding a single flat namespace for the entire program?

I do grant that sometimes shadowing of locals can cause bugs.  I don't
recall right now why we opted for -Wshadow=compatible-local over
-Wshadow=local, but we could certainly take another look at that.

			regards, tom lane