Suppress more variable-set-but-not-used warnings from clang 15.

Mop up assorted set-but-not-used warnings in the back branches.
This includes back-patching relevant fixes from commit 152c9f7b8
the rest of the way, but there are also several cases that did not
appear in HEAD.  Some of those we'd fixed in a retail way but not
back-patched, and others I think just got rewritten out of existence
during nearby refactoring.

While here, also back-patch b1980f6d0 (PL/Tcl: Fix compiler warnings
with Tcl 8.6) into 9.2, so that that branch compiles warning-free
with modern Tcl.

Per project policy, this is a candidate for back-patching into
out-of-support branches: it suppresses annoying compiler warnings
but changes no behavior.  Hence, back-patch all the way to 9.2.

Discussion: https://postgr.es/m/514615.1663615243@sss.pgh.pa.us

diff --git a/src/backend/optimizer/util/var.c b/src/backend/optimizer/util/var.c
index 4e0b533e8f8f520183bb679162985ddbda7c11a1..cdc5c5c1ac628a76aeb68b9709255ab8db649f50 100644 (file)
--- a/src/backend/optimizer/util/var.c
+++ b/src/backend/optimizer/util/var.c
@@ -761,16 +761,13 @@ flatten_join_alias_vars_mutator(Node *node,
            RowExpr    *rowexpr;
            List       *fields = NIL;
            List       *colnames = NIL;
-           AttrNumber  attnum;
            ListCell   *lv;
            ListCell   *ln;
 
-           attnum = 0;
            Assert(list_length(rte->joinaliasvars) == list_length(rte->eref->colnames));
            forboth(lv, rte->joinaliasvars, ln, rte->eref->colnames)
            {
                newvar = (Node *) lfirst(lv);
-               attnum++;
                /* Ignore dropped columns */
                if (newvar == NULL)
                    continue;