Re: [HACKERS] useless assignment pointer argument
On 2015-05-28 20:14:33 +, Gaetano Mendola wrote: src/backend/commands/explain.c:1692 src/backend/commands/explain.c:1874 src/backend/commands/explain.c:1986 there is the following assignment: ancestors = list_delete_first(ancestors); but it has no effect at all being that a function parameter and not used anymore after the assignment itself. So? It costs little to nothing, and it'll make it much less likely that a stale version of 'ancestors' is used when the code is expanded. Greetings, Andres Freund -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
Re: [HACKERS] useless assignment pointer argument
If the compiler is good the assignment is elided indeed, that's not what I meant to point out. On Thu, 28 May 2015 at 22:17 Andres Freund and...@anarazel.de wrote: On 2015-05-28 20:14:33 +, Gaetano Mendola wrote: src/backend/commands/explain.c:1692 src/backend/commands/explain.c:1874 src/backend/commands/explain.c:1986 there is the following assignment: ancestors = list_delete_first(ancestors); but it has no effect at all being that a function parameter and not used anymore after the assignment itself. So? It costs little to nothing, and it'll make it much less likely that a stale version of 'ancestors' is used when the code is expanded. Greetings, Andres Freund
[HACKERS] useless assignment pointer argument
Hi, in the following spots: src/backend/commands/explain.c:1692 src/backend/commands/explain.c:1874 src/backend/commands/explain.c:1986 there is the following assignment: ancestors = list_delete_first(ancestors); but it has no effect at all being that a function parameter and not used anymore after the assignment itself.
Re: [HACKERS] useless assignment pointer argument
Andres Freund and...@anarazel.de writes: On 2015-05-28 20:14:33 +, Gaetano Mendola wrote: src/backend/commands/explain.c:1692 src/backend/commands/explain.c:1874 src/backend/commands/explain.c:1986 there is the following assignment: ancestors = list_delete_first(ancestors); but it has no effect at all being that a function parameter and not used anymore after the assignment itself. So? It costs little to nothing, and it'll make it much less likely that a stale version of 'ancestors' is used when the code is expanded. It's completely mistaken to imagine that the statement has no effect: it does change the underlying List structure, so removing it would be wrong. It's true that we could, today, write it as (void) list_delete_first(ancestors); but this is not any more clear IMO, and it would fail if the code were ever changed so that these functions did use the ancestors list after the point of popping the context they pushed for their children. That risk outweighs any argument about how deleting the assignment would quiet some tool or other. regards, tom lane -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
