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From: Heikki Linnakangas <[email protected]>
To: Chao Li <[email protected]>
To: Postgres hackers <[email protected]>
Subject: Re: Cleanup shadows variable warnings, round 1
Date: Fri, 28 Nov 2025 11:11:04 +0200
Message-ID: <[email protected]> (raw)
In-Reply-To: <CAEoWx2kQ2x5gMaj8tHLJ3=jfC+p5YXHkJyHrDTiQw2nn2FJTmQ@mail.gmail.com>
References: <CAEoWx2kQ2x5gMaj8tHLJ3=jfC+p5YXHkJyHrDTiQw2nn2FJTmQ@mail.gmail.com>

On 28/11/2025 10:16, Chao Li wrote:
> Hi Hackers,
> 
> While reviewing [1], it makes me recall an experience where I had a 
> patch ready locally, but CommitFest CI failed with a shadows-variable 
> warning. Now I understand that -Wall doesn't by default enable -Wshadows 
> with some compilers like clang.
> 
> I did a clean build with manually enabling -Wshadow and 
> surprisingly found there are a lot of such warnings in the current code 
> base, roughly ~200 occurrences.
> 
> As there are too many, I plan to fix them all in 3-4 rounds. For round 1 
> patch, I'd see any objection, then decide if to proceed more rounds.

I don't know if we've agreed on a goal of getting rid of all shadowing, 
it's a lot of code churn. I agree shadowing is often confusing and 
error-prone, so maybe it's worth it.

On the patch itself:

In some of the cases, I think we should rename the global / outer-scoped 
variable instead of the local variable. For example, it's pretty insane 
that we apparently have a global variable called 'days'. :-)

Let's think a little harder about the new names. For example:

> @@ -1274,8 +1274,8 @@ execute_extension_script(Oid extensionOid, ExtensionControlFile *control,
>  			Datum		old = t_sql;
>  			char	   *reqextname = (char *) lfirst(lc);
>  			Oid			reqschema = lfirst_oid(lc2);
> -			char	   *schemaName = get_namespace_name(reqschema);
> -			const char *qSchemaName = quote_identifier(schemaName);
> +			char	   *schemaname = get_namespace_name(reqschema);
> +			const char *qSchemaName = quote_identifier(schemaname);
>  			char	   *repltoken;
>  
>  			repltoken = psprintf("@extschema:%s@", reqextname);

Having two local variables that only differ in case is also confusing. 
We're using the 'req*' prefix here for the other variables, so I think 
e.g. 'reqSchemaName' would be a good name here.

(I didn't go through the whole patch, these were just a few things that 
caught my eye at quick glance)

- Heikki

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