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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
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@ -16075,7 +16075,7 @@ makeOrderedSetArgs(List *directargs, List *orderedargs,
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core_yyscan_t yyscanner)
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{
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FunctionParameter *lastd = (FunctionParameter *) llast(directargs);
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int ndirectargs;
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Value *ndirectargs;
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/* No restriction unless last direct arg is VARIADIC */
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if (lastd->mode == FUNC_PARAM_VARIADIC)
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@ -16099,10 +16099,10 @@ makeOrderedSetArgs(List *directargs, List *orderedargs,
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}
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/* don't merge into the next line, as list_concat changes directargs */
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ndirectargs = list_length(directargs);
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ndirectargs = makeInteger(list_length(directargs));
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return list_make2(list_concat(directargs, orderedargs),
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makeInteger(ndirectargs));
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ndirectargs);
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}
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/* insertSelectOptions()
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