Horton

Re: Silencing the remaining clang 15 warnings

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

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Thomas Munro <thomas.munro@gmail.com>
Cc: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2022-09-19T23:06:53Z
Lists: pgsql-hackers 
Thomas Munro <thomas.munro@gmail.com> writes:
> On Tue, Sep 20, 2022 at 7:20 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> * xlog.c's AdvanceXLInsertBuffer has a local variable "npages"
>> that is only read in the "#ifdef WAL_DEBUG" stanza at the
>> bottom.  Here I've done the rather ugly and brute-force thing
>> of wrapping all the variable's references in "#ifdef WAL_DEBUG".
>> (I tried marking it PG_USED_FOR_ASSERTS_ONLY, but oddly that
>> did not silence the warning.)  I kind of wonder how useful this
>> function's WAL_DEBUG output is --- maybe just dropping that
>> altogether would be better?

> No opinion on the value of the message, but maybe
> pg_attribute_unused() would be better?

I realized that the reason PG_USED_FOR_ASSERTS_ONLY didn't help
is that it expands to empty in an assert-enabled build, which is
what I was testing.  So yeah, using pg_attribute_unused() directly
would probably work better.

(Also, I tried an assert-disabled build and found one additional new
warning; same deal where clang doesn't believe "foo++;" is reason to
consider foo to be used.  That one, PG_USED_FOR_ASSERTS_ONLY can fix.)

			regards, tom lane

Commits

  1. Fix configure's AC_CHECK_DECLS tests to work correctly with clang.

  2. Suppress more variable-set-but-not-used warnings from clang 15.

  3. Suppress variable-set-but-not-used warnings from clang 15.