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Since we introduced the idea of leakproof functions, texteq and textne were marked leakproof but their sibling text comparison functions were not. This inconsistency seemed justified because texteq/textne just relied on memcmp() and so could easily be seen to be leakproof, while the other comparison functions are far more complex and indeed can throw input-dependent errors. However, that argument crashed and burned with the addition of nondeterministic collations, because now texteq/textne may invoke the exact same varstr_cmp() infrastructure as the rest. It makes no sense whatever to give them different leakproofness markings. After a certain amount of angst we've concluded that it's all right to consider varstr_cmp() to be leakproof, mostly because the other choice would be disastrous for performance of many queries where leakproofness matters. The input-dependent errors should only be reachable for corrupt input data, or so we hope anyway; certainly, if they are reachable in practice, we've got problems with requirements as basic as maintaining a btree index on a text column. Hence, run around to all the SQL functions that derive from varstr_cmp() and mark them leakproof. This should result in a useful gain in flexibility/performance for queries in which non-leakproofness degrades the efficiency of the query plan. Back-patch to v12 where nondeterministic collations were added. While this isn't an essential bug fix given the determination that varstr_cmp() is leakproof, we might as well apply it now that we've been forced into a post-beta4 catversion bump. Discussion: https://postgr.es/m/31481.1568303470@sss.pgh.pa.us