pgsql: Fix optimization hazard in gram.y's makeOrderedSetArgs(), redux. - Mailing list pgsql-committers

From Tom Lane
Subject pgsql: Fix optimization hazard in gram.y's makeOrderedSetArgs(), redux.
Date
Msg-id E1kQI9a-0003zS-Lm@gemulon.postgresql.org
Whole thread Raw
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Fix optimization hazard in gram.y's makeOrderedSetArgs(), redux.

It appears that commit cf63c641c, which intended to prevent
misoptimization of the result-building step in makeOrderedSetArgs,
didn't go far enough: buildfarm member hornet's version of xlc
is now optimizing back to the old, broken behavior in which
list_length(directargs) is fetched only after list_concat() has
changed that value.  I'm not entirely convinced whether that's
an undeniable compiler bug or whether it can be justified by a
sufficiently aggressive interpretation of C sequence points.
So let's just change the code to make it harder to misinterpret.

Back-patch to all supported versions, just in case.

Discussion: https://postgr.es/m/1830491.1601944935@sss.pgh.pa.us

Branch
------
REL_12_STABLE

Details
-------
https://git.postgresql.org/pg/commitdiff/8b231d9753287fc16328af2ab31943b79e1cc8a3

Modified Files
--------------
src/backend/parser/gram.y | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)


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