From: Tom Lane <tgl@sss.pgh.pa.us>
To: Andres Freund <andres@anarazel.de>
cc: pgsql-committers@lists.postgresql.org
Subject: Re: pgsql: aio: Add core asynchronous I/O infrastructure
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Comments: In-reply-to Andres Freund <andres@anarazel.de>
	message dated "Mon, 17 Mar 2025 23:23:42 -0000"
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Date: Tue, 18 Mar 2025 11:03:36 -0400
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Andres Freund <andres@anarazel.de> writes:
> aio: Add core asynchronous I/O infrastructure

Some of the buildfarm is mildly unhappy with this.
So far I see

 ayu           | 2025-03-18 13:08:04 | aio_callback.c:83:12: warning: comp=
arison of constant 1 with expression of type 'PgAioHandleCallbackID' (aka =
'enum PgAioHandleCallbackID') is always false [-Wtautological-constant-out=
-of-range-compare]
 ayu           | 2025-03-18 13:08:04 | aio_callback.c:190:56: warning: com=
parison of constant 1 with expression of type 'PgAioTargetID' (aka 'enum P=
gAioTargetID') is always true [-Wtautological-constant-out-of-range-compar=
e]
 ayu           | 2025-03-18 13:08:04 | aio_callback.c:220:56: warning: com=
parison of constant 1 with expression of type 'PgAioTargetID' (aka 'enum P=
gAioTargetID') is always true [-Wtautological-constant-out-of-range-compar=
e]
 ayu           | 2025-03-18 13:08:04 | aio_callback.c:274:56: warning: com=
parison of constant 1 with expression of type 'PgAioTargetID' (aka 'enum P=
gAioTargetID') is always true [-Wtautological-constant-out-of-range-compar=
e]
 ayu           | 2025-03-18 13:08:04 | aio_target.c:50:41: warning: compar=
ison of constant 1 with expression of type 'PgAioTargetID' (aka 'enum PgAi=
oTargetID') is always true [-Wtautological-constant-out-of-range-compare]
 ayu           | 2025-03-18 13:08:04 | aio_target.c:110:41: warning: compa=
rison of constant 1 with expression of type 'PgAioTargetID' (aka 'enum PgA=
ioTargetID') is always true [-Wtautological-constant-out-of-range-compare]
 demoiselle    | 2025-03-18 03:43:46 | aio_callback.c:83:12: warning: comp=
arison of constant 1 with expression of type 'PgAioHandleCallbackID' (aka =
'enum PgAioHandleCallbackID') is always false [-Wtautological-constant-out=
-of-range-compare]
 demoiselle    | 2025-03-18 03:43:46 | aio_callback.c:190:56: warning: com=
parison of constant 1 with expression of type 'PgAioTargetID' (aka 'enum P=
gAioTargetID') is always true [-Wtautological-constant-out-of-range-compar=
e]
 demoiselle    | 2025-03-18 03:43:46 | aio_callback.c:220:56: warning: com=
parison of constant 1 with expression of type 'PgAioTargetID' (aka 'enum P=
gAioTargetID') is always true [-Wtautological-constant-out-of-range-compar=
e]
 demoiselle    | 2025-03-18 03:43:46 | aio_callback.c:274:56: warning: com=
parison of constant 1 with expression of type 'PgAioTargetID' (aka 'enum P=
gAioTargetID') is always true [-Wtautological-constant-out-of-range-compar=
e]
 demoiselle    | 2025-03-18 03:43:46 | aio_target.c:50:41: warning: compar=
ison of constant 1 with expression of type 'PgAioTargetID' (aka 'enum PgAi=
oTargetID') is always true [-Wtautological-constant-out-of-range-compare]
 demoiselle    | 2025-03-18 03:43:46 | aio_target.c:110:41: warning: compa=
rison of constant 1 with expression of type 'PgAioTargetID' (aka 'enum PgA=
ioTargetID') is always true [-Wtautological-constant-out-of-range-compare]

I don't have that compiler handy to check, but maybe changes like

-	if (cb_id >=3D lengthof(aio_handle_cbs))
+	if ((size_t) cb_id >=3D lengthof(aio_handle_cbs))

would silence these?  Or you could just drop all those tests
and have faith in the type-safety of the enums.

			regards, tom lane