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

clang 15+ will issue a set-but-not-used warning when the only
use of a variable is in autoincrements (e.g., "foo++;").
That's perfectly sensible, but it detects a few more cases that
we'd not noticed before.  Silence the warnings with our usual
methods, such as PG_USED_FOR_ASSERTS_ONLY, or in one case by
actually removing a useless variable.

One thing that we can't nicely get rid of is that with %pure-parser,
Bison emits "yynerrs" as a local variable that falls foul of this
warning.  To silence those, I inserted "(void) yynerrs;" in the
top-level productions of affected grammars.

Per recently-established 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 to 9.5, which is as far as these patches go without
issues.  (A preliminary check shows that the prior branches
need some other set-but-not-used cleanups too, so I'll leave
them for another day.)

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

diff --git a/src/backend/access/gist/gistxlog.c b/src/backend/access/gist/gistxlog.c
index 17e213967b9a706f90e4ad993da01f7a0556f7c9..3ca4bf151911542616ef3cbc36e3b0c2dc471d3b 100644 (file)
--- a/src/backend/access/gist/gistxlog.c
+++ b/src/backend/access/gist/gistxlog.c
@@ -257,7 +257,7 @@ gistRedoPageUpdateRecord(XLogReaderState *record)
        char       *begin;
        char       *data;
        Size        datalen;
-       int         ninserted = 0;
+       int         ninserted PG_USED_FOR_ASSERTS_ONLY = 0;
 
        data = begin = XLogRecGetBlockData(record, 0, &datalen);
 

diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index eed6dc6457a58efb32d861f68e04e6df37ef55a4..3f5776c24606da200f252001e8e9394645fbf0ac 100644 (file)
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -2102,7 +2102,7 @@ AdvanceXLInsertBuffer(XLogRecPtr upto, bool opportunistic)
    XLogRecPtr  NewPageEndPtr = InvalidXLogRecPtr;
    XLogRecPtr  NewPageBeginPtr;
    XLogPageHeader NewPage;
-   int         npages = 0;
+   int         npages pg_attribute_unused() = 0;
 
    LWLockAcquire(WALBufMappingLock, LW_EXCLUSIVE);
 

diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 2dc444c5e8aac57b034534fa3c92520ab7a4182c..a741fbd05ca32d7a6cba56de35add91dfd551108 100644 (file)
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -784,6 +784,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 stmtblock: stmtmulti
            {
                pg_yyget_extra(yyscanner)->parsetree = $1;
+               (void) yynerrs;     /* suppress compiler warning */
            }
        ;
 

diff --git a/src/backend/utils/adt/array_typanalyze.c b/src/backend/utils/adt/array_typanalyze.c
index 92e38b870f516f4b58f9c0197650b796a426b984..c55aff13b06c3ef369b890aa32ab9b3706b15146 100644 (file)
--- a/src/backend/utils/adt/array_typanalyze.c
+++ b/src/backend/utils/adt/array_typanalyze.c
@@ -217,7 +217,6 @@ compute_array_stats(VacAttrStats *stats, AnalyzeAttrFetchFunc fetchfunc,
 {
    ArrayAnalyzeExtraData *extra_data;
    int         num_mcelem;
-   int         null_cnt = 0;
    int         null_elem_cnt = 0;
    int         analyzed_rows = 0;
 
@@ -321,8 +320,7 @@ compute_array_stats(VacAttrStats *stats, AnalyzeAttrFetchFunc fetchfunc,
        value = fetchfunc(stats, array_no, &isnull);
        if (isnull)
        {
-           /* array is null, just count that */
-           null_cnt++;
+           /* ignore arrays that are null overall */
            continue;
        }
 

diff --git a/src/bin/pgbench/exprparse.y b/src/bin/pgbench/exprparse.y
index f7c56cc6a31f0e5c5067626c73ff5de6a88902e6..e59d1a2f7b34c2bd1a91299a2feb346779a87aec 100644 (file)
--- a/src/bin/pgbench/exprparse.y
+++ b/src/bin/pgbench/exprparse.y
@@ -78,7 +78,10 @@ static PgBenchExpr *make_case(yyscan_t yyscanner, PgBenchExprList *when_then_lis
 
 %%
 
-result: expr               { expr_parse_result = $1; }
+result: expr               {
+                               expr_parse_result = $1;
+                               (void) yynerrs; /* suppress compiler warning */
+                           }
 
 elist:                     { $$ = NULL; }
    | expr                  { $$ = make_elist($1, NULL); }