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 fbdbb3c51f2e7fc7e40c918bffe063537836233e..7a8fdd853545d1e35369bc68fc832c4fc7d44da9 100644 (file)
--- a/src/backend/access/gist/gistxlog.c
+++ b/src/backend/access/gist/gistxlog.c
@@ -74,7 +74,7 @@ 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 f5a1599cb374a242f0cbdd57e56633011766b424..c3fe12714653a748205f0224542edd7d3563c327 100644 (file)
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1905,7 +1905,7 @@ 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 617e577b6636dd97fe43cdfe051e8bcd4a39bcc2..24bdb86bc2c9cc5482f10e9e8dfb3c1538d79859 100644 (file)
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -732,6 +732,7 @@ 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 ffe8035eb4d53a4266f8e0738a1b6bc25b0e3dd0..e2ded3ccd47bbc77f33ff172e35ba5d1dcf2c682 100644 (file)
--- a/src/backend/utils/adt/array_typanalyze.c
+++ b/src/backend/utils/adt/array_typanalyze.c
@@ -216,7 +216,6 @@ 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;
 
@@ -320,8 +319,7 @@ 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;
        }