Add assert() statements and eliminate needless variable assignments in order

to get the clang scan-build utility to report zero problems against the
SQLite core.  Clang's static analysis did find one real problem - but it was
in the command-line shell, not in the SQLite core.

FossilOrigin-Name: 60fee9574b0125705787e33c16f116cf188c8323

16 files changed, 89 insertions, 77 deletions

diff --git a/src/btree.c b/src/btree.c
index f1a67cab9..6c724d0fa 100644
--- a/src/btree.c
+++ b/src/btree.c
@@ -4585,7 +4585,6 @@ int sqlite3BtreeMovetoUnpacked(
       if( c==0 ){
         if( pPage->intKey && !pPage->leaf ){
           lwr = idx;
-          upr = lwr - 1;
           break;
         }else{
           *pRes = 0;
@@ -4603,7 +4602,7 @@ int sqlite3BtreeMovetoUnpacked(
       }
       pCur->aiIdx[pCur->iPage] = (u16)(idx = (lwr+upr)/2);
     }
-    assert( lwr==upr+1 );
+    assert( lwr==upr+1 || (pPage->intKey && !pPage->leaf) );
     assert( pPage->isInit );
     if( pPage->leaf ){
       chldPg = 0;
@@ -4868,6 +4867,8 @@ static int allocateBtreePage(
         pTrunk = 0;
         goto end_allocate_page;
       }
+      assert( pTrunk!=0 );
+      assert( pTrunk->aData!=0 );
 
       k = get4byte(&pTrunk->aData[4]); /* # of leaves on this trunk page */
       if( k==0 && !searchList ){
@@ -6423,6 +6424,7 @@ static int balance_nonroot(
         /* Cell i is the cell immediately following the last cell on old
         ** sibling page j. If the siblings are not leaf pages of an
         ** intkey b-tree, then cell i was a divider cell. */
+        assert( j+1 < ArraySize(apCopy) );
         pOld = apCopy[++j];
         iNextOld = i + !leafData + pOld->nCell + pOld->nOverflow;
         if( pOld->nOverflow ){
diff --git a/src/build.c b/src/build.c
index d7f08e496..050643d18 100644
--- a/src/build.c
+++ b/src/build.c
@@ -2342,13 +2342,15 @@ static void sqlite3RefillIndex(Parse *pParse, Index *pIndex, int memRootPage){
   Table *pTab = pIndex->pTable;  /* The table that is indexed */
   int iTab = pParse->nTab++;     /* Btree cursor used for pTab */
   int iIdx = pParse->nTab++;     /* Btree cursor used for pIndex */
-  int iSorter = iTab;            /* Cursor opened by OpenSorter (if in use) */
+  int iSorter;                   /* Cursor opened by OpenSorter (if in use) */
   int addr1;                     /* Address of top of loop */
   int addr2;                     /* Address to jump to for next iteration */
   int tnum;                      /* Root page of index */
   Vdbe *v;                       /* Generate code into this virtual machine */
   KeyInfo *pKey;                 /* KeyInfo for index */
+#ifdef SQLITE_OMIT_MERGE_SORT
   int regIdxKey;                 /* Registers containing the index key */
+#endif
   int regRecord;                 /* Register holding assemblied index record */
   sqlite3 *db = pParse->db;      /* The database connection */
   int iDb = sqlite3SchemaToIndex(db, pIndex->pSchema);
@@ -2382,17 +2384,18 @@ static void sqlite3RefillIndex(Parse *pParse, Index *pIndex, int memRootPage){
   /* Open the sorter cursor if we are to use one. */
   iSorter = pParse->nTab++;
   sqlite3VdbeAddOp4(v, OP_SorterOpen, iSorter, 0, 0, (char*)pKey, P4_KEYINFO);
+#else
+  iSorter = iTab;
 #endif
 
   /* Open the table. Loop through all rows of the table, inserting index
   ** records into the sorter. */
   sqlite3OpenTable(pParse, iTab, iDb, pTab, OP_OpenRead);
   addr1 = sqlite3VdbeAddOp2(v, OP_Rewind, iTab, 0);
-  addr2 = addr1 + 1;
   regRecord = sqlite3GetTempReg(pParse);
-  regIdxKey = sqlite3GenerateIndexKey(pParse, pIndex, iTab, regRecord, 1);
 
 #ifndef SQLITE_OMIT_MERGE_SORT
+  sqlite3GenerateIndexKey(pParse, pIndex, iTab, regRecord, 1);
   sqlite3VdbeAddOp2(v, OP_SorterInsert, iSorter, regRecord);
   sqlite3VdbeAddOp2(v, OP_Next, iTab, addr1+1);
   sqlite3VdbeJumpHere(v, addr1);
@@ -2412,6 +2415,8 @@ static void sqlite3RefillIndex(Parse *pParse, Index *pIndex, int memRootPage){
   sqlite3VdbeAddOp3(v, OP_IdxInsert, iIdx, regRecord, 1);
   sqlite3VdbeChangeP5(v, OPFLAG_USESEEKRESULT);
 #else
+  regIdxKey = sqlite3GenerateIndexKey(pParse, pIndex, iTab, regRecord, 1);
+  addr2 = addr1 + 1;
   if( pIndex->onError!=OE_None ){
     const int regRowid = regIdxKey + pIndex->nColumn;
     const int j2 = sqlite3VdbeCurrentAddr(v) + 2;
@@ -2509,6 +2514,7 @@ Index *sqlite3CreateIndex(
     assert( pName1 && pName2 );
     iDb = sqlite3TwoPartName(pParse, pName1, pName2, &pName);
     if( iDb<0 ) goto exit_create_index;
+    assert( pName && pName->z );
 
 #ifndef SQLITE_OMIT_TEMPDB
     /* If the index name was unqualified, check if the the table
@@ -2536,6 +2542,7 @@ Index *sqlite3CreateIndex(
     assert( db->aDb[iDb].pSchema==pTab->pSchema );
   }else{
     assert( pName==0 );
+    assert( pStart==0 );
     pTab = pParse->pNewTable;
     if( !pTab ) goto exit_create_index;
     iDb = sqlite3SchemaToIndex(db, pTab->pSchema);
@@ -2578,6 +2585,7 @@ Index *sqlite3CreateIndex(
   if( pName ){
     zName = sqlite3NameFromToken(db, pName);
     if( zName==0 ) goto exit_create_index;
+    assert( pName->z!=0 );
     if( SQLITE_OK!=sqlite3CheckObjectName(pParse, zName) ){
       goto exit_create_index;
     }
@@ -3433,13 +3441,10 @@ void sqlite3BeginTransaction(Parse *pParse, int type){
 ** Commit a transaction
 */
 void sqlite3CommitTransaction(Parse *pParse){
-  sqlite3 *db;
   Vdbe *v;
 
   assert( pParse!=0 );
-  db = pParse->db;
-  assert( db!=0 );
-/*  if( db->aDb[0].pBt==0 ) return; */
+  assert( pParse->db!=0 );
   if( sqlite3AuthCheck(pParse, SQLITE_TRANSACTION, "COMMIT", 0, 0) ){
     return;
   }
@@ -3453,13 +3458,10 @@ void sqlite3CommitTransaction(Parse *pParse){
 ** Rollback a transaction
 */
 void sqlite3RollbackTransaction(Parse *pParse){
-  sqlite3 *db;
   Vdbe *v;
 
   assert( pParse!=0 );
-  db = pParse->db;
-  assert( db!=0 );
-/*  if( db->aDb[0].pBt==0 ) return; */
+  assert( pParse->db!=0 );
   if( sqlite3AuthCheck(pParse, SQLITE_TRANSACTION, "ROLLBACK", 0, 0) ){
     return;
   }
diff --git a/src/expr.c b/src/expr.c
index 3e144612c..d50617377 100644
--- a/src/expr.c
+++ b/src/expr.c
@@ -403,7 +403,8 @@ Expr *sqlite3ExprAlloc(
       }else{
         int c;
         pNew->u.zToken = (char*)&pNew[1];
-        memcpy(pNew->u.zToken, pToken->z, pToken->n);
+        assert( pToken->z!=0 || pToken->n==0 );
+        if( pToken->n ) memcpy(pNew->u.zToken, pToken->z, pToken->n);
         pNew->u.zToken[pToken->n] = 0;
         if( dequote && nExtra>=3 
              && ((c = pToken->z[0])=='\'' || c=='"' || c=='[' || c=='`') ){
@@ -1442,11 +1443,19 @@ int sqlite3FindInIndex(Parse *pParse, Expr *pX, int *prNotFound){
   p = (ExprHasProperty(pX, EP_xIsSelect) ? pX->x.pSelect : 0);
   if( ALWAYS(pParse->nErr==0) && isCandidateForInOpt(p) ){
     sqlite3 *db = pParse->db;              /* Database connection */
-    Expr *pExpr = p->pEList->a[0].pExpr;   /* Expression <column> */
-    int iCol = pExpr->iColumn;             /* Index of column <column> */
     Vdbe *v = sqlite3GetVdbe(pParse);      /* Virtual machine being coded */
-    Table *pTab = p->pSrc->a[0].pTab;      /* Table <table>. */
+    Table *pTab;                           /* Table <table>. */
+    Expr *pExpr;                           /* Expression <column> */
+    int iCol;                              /* Index of column <column> */
     int iDb;                               /* Database idx for pTab */
+
+    assert( p );                        /* Because of isCandidateForInOpt(p) */
+    assert( p->pEList!=0 );             /* Because of isCandidateForInOpt(p) */
+    assert( p->pEList->a[0].pExpr!=0 ); /* Because of isCandidateForInOpt(p) */
+    assert( p->pSrc!=0 );               /* Because of isCandidateForInOpt(p) */
+    pTab = p->pSrc->a[0].pTab;
+    pExpr = p->pEList->a[0].pExpr;
+    iCol = pExpr->iColumn;
    
     /* Code an OP_VerifyCookie and OP_TableLock for <table>. */
     iDb = sqlite3SchemaToIndex(db, pTab->pSchema);
diff --git a/src/fkey.c b/src/fkey.c
index f0a9fb6ba..82e4cdc47 100644
--- a/src/fkey.c
+++ b/src/fkey.c
@@ -1124,6 +1124,7 @@ static Trigger *fkActionTrigger(
       fkTriggerDelete(db, pTrigger);
       return 0;
     }
+    assert( pStep!=0 );
 
     switch( action ){
       case OE_Restrict:
diff --git a/src/main.c b/src/main.c
index 51596c1de..b18217d34 100644
--- a/src/main.c
+++ b/src/main.c
@@ -2282,6 +2282,7 @@ opendb_out:
     sqlite3_mutex_leave(db->mutex);
   }
   rc = sqlite3_errcode(db);
+  assert( db!=0 || rc==SQLITE_NOMEM );
   if( rc==SQLITE_NOMEM ){
     sqlite3_close(db);
     db = 0;
diff --git a/src/os_unix.c b/src/os_unix.c
index e0025229f..0236bf7cc 100644
--- a/src/os_unix.c
+++ b/src/os_unix.c
@@ -1363,14 +1363,14 @@ static int unixLock(sqlite3_file *id, int eFileLock){
   */
   int rc = SQLITE_OK;
   unixFile *pFile = (unixFile*)id;
-  unixInodeInfo *pInode = pFile->pInode;
+  unixInodeInfo *pInode;
   struct flock lock;
   int tErrno = 0;
 
   assert( pFile );
   OSTRACE(("LOCK    %d %s was %s(%s,%d) pid=%d (unix)\n", pFile->h,
       azFileLock(eFileLock), azFileLock(pFile->eFileLock),
-      azFileLock(pInode->eFileLock), pInode->nShared , getpid()));
+      azFileLock(pFile->pInode->eFileLock), pFile->pInode->nShared , getpid()));
 
   /* If there is already a lock of this type or more restrictive on the
   ** unixFile, do nothing. Don't use the end_lock: exit path, as
@@ -1574,7 +1574,6 @@ static int posixUnlock(sqlite3_file *id, int eFileLock, int handleNFSUnlock){
   unixInodeInfo *pInode;
   struct flock lock;
   int rc = SQLITE_OK;
-  int h;
 
   assert( pFile );
   OSTRACE(("UNLOCK  %d %d was %d(%d,%d) pid=%d (unix)\n", pFile->h, eFileLock,
@@ -1586,14 +1585,10 @@ static int posixUnlock(sqlite3_file *id, int eFileLock, int handleNFSUnlock){
     return SQLITE_OK;
   }
   unixEnterMutex();
-  h = pFile->h;
   pInode = pFile->pInode;
   assert( pInode->nShared!=0 );
   if( pFile->eFileLock>SHARED_LOCK ){
     assert( pInode->eFileLock==pFile->eFileLock );
-    SimulateIOErrorBenign(1);
-    SimulateIOError( h=(-1) )
-    SimulateIOErrorBenign(0);
 
 #ifndef NDEBUG
     /* When reducing a lock such that other processes can start
@@ -1604,11 +1599,6 @@ static int posixUnlock(sqlite3_file *id, int eFileLock, int handleNFSUnlock){
     ** the file has changed and hence might not know to flush their
     ** cache.  The use of a stale cache can lead to database corruption.
     */
-#if 0
-    assert( pFile->inNormalWrite==0
-         || pFile->dbUpdate==0
-         || pFile->transCntrChng==1 );
-#endif
     pFile->inNormalWrite = 0;
 #endif
 
@@ -1710,9 +1700,6 @@ static int posixUnlock(sqlite3_file *id, int eFileLock, int handleNFSUnlock){
       lock.l_type = F_UNLCK;
       lock.l_whence = SEEK_SET;
       lock.l_start = lock.l_len = 0L;
-      SimulateIOErrorBenign(1);
-      SimulateIOError( h=(-1) )
-      SimulateIOErrorBenign(0);
       if( unixFileLock(pFile, &lock)==0 ){
         pInode->eFileLock = NO_LOCK;
       }else{
@@ -4548,6 +4535,9 @@ static int fillInUnixFile(
   assert( zFilename==0 || zFilename[0]=='/' );
 #endif
 
+  /* No locking occurs in temporary files */
+  assert( zFilename!=0 || noLock );
+
   OSTRACE(("OPEN    %-3d %s\n", h, zFilename));
   pNew->h = h;
   pNew->zPath = zFilename;
@@ -4649,6 +4639,7 @@ static int fillInUnixFile(
     */
     char *zLockFile;
     int nFilename;
+    assert( zFilename!=0 );
     nFilename = (int)strlen(zFilename) + 6;
     zLockFile = (char *)sqlite3_malloc(nFilename);
     if( zLockFile==0 ){
diff --git a/src/pager.c b/src/pager.c
index 99a3ebd4c..421a7094f 100644
--- a/src/pager.c
+++ b/src/pager.c
@@ -2703,7 +2703,6 @@ static int pager_playback(Pager *pPager, int isHot){
       rc = pager_playback_one_page(pPager,&pPager->journalOff,0,1,0);
       if( rc!=SQLITE_OK ){
         if( rc==SQLITE_DONE ){
-          rc = SQLITE_OK;
           pPager->journalOff = szJ;
           break;
         }else if( rc==SQLITE_IOERR_SHORT_READ ){
@@ -2965,6 +2964,7 @@ static int pagerWalFrames(
 #endif
 
   assert( pPager->pWal );
+  assert( pList );
 #ifdef SQLITE_DEBUG
   /* Verify that the page list is in accending order */
   for(p=pList; p && p->pDirty; p=p->pDirty){
diff --git a/src/printf.c b/src/printf.c
index 1303e17ed..0babee514 100644
--- a/src/printf.c
+++ b/src/printf.c
@@ -197,7 +197,6 @@ void sqlite3VXPrintf(
 #endif
   char buf[etBUFSIZE];       /* Conversion buffer */
 
-  length = 0;
   bufpt = 0;
   for(; (c=(*fmt))!=0; ++fmt){
     if( c!='%' ){
@@ -692,6 +691,7 @@ void sqlite3StrAccumAppend(StrAccum *p, const char *z, int N){
     testcase(p->mallocFailed);
     return;
   }
+  assert( p->zText!=0 || p->nChar==0 );
   if( N<0 ){
     N = sqlite3Strlen30(z);
   }
@@ -723,7 +723,7 @@ void sqlite3StrAccumAppend(StrAccum *p, const char *z, int N){
         zNew = sqlite3_realloc(zOld, p->nAlloc);
       }
       if( zNew ){
-        if( zOld==0 ) memcpy(zNew, p->zText, p->nChar);
+        if( zOld==0 && p->nChar>0 ) memcpy(zNew, p->zText, p->nChar);
         p->zText = zNew;
       }else{
         p->mallocFailed = 1;
@@ -732,6 +732,7 @@ void sqlite3StrAccumAppend(StrAccum *p, const char *z, int N){
       }
     }
   }
+  assert( p->zText );
   memcpy(&p->zText[p->nChar], z, N);
   p->nChar += N;
 }
diff --git a/src/select.c b/src/select.c
index cf9a00a8d..571a77822 100644
--- a/src/select.c
+++ b/src/select.c
@@ -1272,7 +1272,10 @@ static int selectColumnsFromExprList(
     }else{
       Expr *pColExpr = p;  /* The expression that is the result column name */
       Table *pTab;         /* Table associated with this expression */
-      while( pColExpr->op==TK_DOT ) pColExpr = pColExpr->pRight;
+      while( pColExpr->op==TK_DOT ){
+        pColExpr = pColExpr->pRight;
+        assert( pColExpr!=0 );
+      }
       if( pColExpr->op==TK_COLUMN && ALWAYS(pColExpr->pTab!=0) ){
         /* For columns use the column name name */
         int iCol = pColExpr->iColumn;
diff --git a/src/shell.c b/src/shell.c
index 58a48db12..07623e52a 100644
--- a/src/shell.c
+++ b/src/shell.c
@@ -338,7 +338,6 @@ static char *local_getline(char *zPrompt, FILE *in){
   char *zLine;
   int nLine;
   int n;
-  int eol;
 
   if( zPrompt && *zPrompt ){
     printf("%s",zPrompt);
@@ -348,8 +347,7 @@ static char *local_getline(char *zPrompt, FILE *in){
   zLine = malloc( nLine );
   if( zLine==0 ) return 0;
   n = 0;
-  eol = 0;
-  while( !eol ){
+  while( 1 ){
     if( n+100>nLine ){
       nLine = nLine*2 + 100;
       zLine = realloc(zLine, nLine);
@@ -361,7 +359,6 @@ static char *local_getline(char *zPrompt, FILE *in){
         return 0;
       }
       zLine[n] = 0;
-      eol = 1;
       break;
     }
     while( zLine[n] ){ n++; }
@@ -369,7 +366,7 @@ static char *local_getline(char *zPrompt, FILE *in){
       n--;
       if( n>0 && zLine[n-1]=='\r' ) n--;
       zLine[n] = 0;
-      eol = 1;
+      break;
     }
   }
   zLine = realloc( zLine, n+1 );
@@ -1097,6 +1094,7 @@ static int shell_exec(
 ){
   sqlite3_stmt *pStmt = NULL;     /* Statement to execute. */
   int rc = SQLITE_OK;             /* Return Code */
+  int rc2;
   const char *zLeftover;          /* Tail of unprocessed SQL */
 
   if( pzErrMsg ){
@@ -1190,7 +1188,8 @@ static int shell_exec(
       /* Finalize the statement just executed. If this fails, save a 
       ** copy of the error message. Otherwise, set zSql to point to the
       ** next statement to execute. */
-      rc = sqlite3_finalize(pStmt);
+      rc2 = sqlite3_finalize(pStmt);
+      if( rc!=SQLITE_NOMEM ) rc = rc2;
       if( rc==SQLITE_OK ){
         zSql = zLeftover;
         while( IsSpace(zSql[0]) ) zSql++;
@@ -1762,7 +1761,6 @@ static int do_meta_command(char *zLine, struct callback_data *p){
     zCommit = "COMMIT";
     while( (zLine = local_getline(0, in))!=0 ){
       char *z;
-      i = 0;
       lineno++;
       azCol[0] = zLine;
       for(i=0, z=zLine; *z && *z!='\n' && *z!='\r'; z++){
@@ -2237,7 +2235,7 @@ static int do_meta_command(char *zLine, struct callback_data *p){
         if( testctrl<0 ){
           testctrl = aCtrl[i].ctrlCode;
         }else{
-          fprintf(stderr, "ambiguous option name: \"%s\"\n", azArg[i]);
+          fprintf(stderr, "ambiguous option name: \"%s\"\n", azArg[1]);
           testctrl = -1;
           break;
         }
@@ -2745,6 +2743,7 @@ int main(int argc, char **argv){
     }else if( strcmp(argv[i],"-batch")==0 ){
       stdin_is_interactive = 0;
     }else if( strcmp(argv[i],"-heap")==0 ){
+#if defined(SQLITE_ENABLE_MEMSYS3) || defined(SQLITE_ENABLE_MEMSYS5)
       int j, c;
       const char *zSize;
       sqlite3_int64 szHeap;
@@ -2757,7 +2756,6 @@ int main(int argc, char **argv){
         if( c=='G' ){ szHeap *= 1000000000; break; }
       }
       if( szHeap>0x7fff0000 ) szHeap = 0x7fff0000;
-#if defined(SQLITE_ENABLE_MEMSYS3) || defined(SQLITE_ENABLE_MEMSYS5)
       sqlite3_config(SQLITE_CONFIG_HEAP, malloc((int)szHeap), (int)szHeap, 64);
 #endif
 #ifdef SQLITE_ENABLE_VFSTRACE
diff --git a/src/tclsqlite.c b/src/tclsqlite.c
index 35dd0ad8a..c8f0fbd31 100644
--- a/src/tclsqlite.c
+++ b/src/tclsqlite.c
@@ -919,7 +919,7 @@ static int auth_callback(
   Tcl_DStringAppendElement(&str, zArg4 ? zArg4 : "");
   rc = Tcl_GlobalEval(pDb->interp, Tcl_DStringValue(&str));
   Tcl_DStringFree(&str);
-  zReply = Tcl_GetStringResult(pDb->interp);
+  zReply = rc==TCL_OK ? Tcl_GetStringResult(pDb->interp) : "SQLITE_DENY";
   if( strcmp(zReply,"SQLITE_OK")==0 ){
     rc = SQLITE_OK;
   }else if( strcmp(zReply,"SQLITE_DENY")==0 ){
@@ -968,14 +968,12 @@ static char *local_getline(char *zPrompt, FILE *in){
   char *zLine;
   int nLine;
   int n;
-  int eol;
 
   nLine = 100;
   zLine = malloc( nLine );
   if( zLine==0 ) return 0;
   n = 0;
-  eol = 0;
-  while( !eol ){
+  while( 1 ){
     if( n+100>nLine ){
       nLine = nLine*2 + 100;
       zLine = realloc(zLine, nLine);
@@ -987,14 +985,13 @@ static char *local_getline(char *zPrompt, FILE *in){
         return 0;
       }
       zLine[n] = 0;
-      eol = 1;
       break;
     }
     while( zLine[n] ){ n++; }
     if( n>0 && zLine[n-1]=='\n' ){
       n--;
       zLine[n] = 0;
-      eol = 1;
+      break;
     }
   }
   zLine = realloc( zLine, n+1 );
@@ -2121,7 +2118,6 @@ static int DbObjCmd(void *cd, Tcl_Interp *interp, int objc,Tcl_Obj *const*objv){
     zCommit = "COMMIT";
     while( (zLine = local_getline(0, in))!=0 ){
       char *z;
-      i = 0;
       lineno++;
       azCol[0] = zLine;
       for(i=0, z=zLine; *z; z++){
@@ -2550,14 +2546,16 @@ static int DbObjCmd(void *cd, Tcl_Interp *interp, int objc,Tcl_Obj *const*objv){
   ** Change the encryption key on the currently open database.
   */
   case DB_REKEY: {
+#ifdef SQLITE_HAS_CODEC
     int nKey;
     void *pKey;
+#endif
     if( objc!=3 ){
       Tcl_WrongNumArgs(interp, 2, objv, "KEY");
       return TCL_ERROR;
     }
-    pKey = Tcl_GetByteArrayFromObj(objv[2], &nKey);
 #ifdef SQLITE_HAS_CODEC
+    pKey = Tcl_GetByteArrayFromObj(objv[2], &nKey);
     rc = sqlite3_rekey(pDb->db, pKey, nKey);
     if( rc ){
       Tcl_AppendResult(interp, sqlite3ErrStr(rc), 0);
@@ -2920,8 +2918,6 @@ static int DbObjCmdAdaptor(
 */
 static int DbMain(void *cd, Tcl_Interp *interp, int objc,Tcl_Obj *const*objv){
   SqliteDb *p;
-  void *pKey = 0;
-  int nKey = 0;
   const char *zArg;
   char *zErrMsg;
   int i;
@@ -2929,6 +2925,10 @@ static int DbMain(void *cd, Tcl_Interp *interp, int objc,Tcl_Obj *const*objv){
   const char *zVfs = 0;
   int flags;
   Tcl_DString translatedFilename;
+#ifdef SQLITE_HAS_CODEC
+  void *pKey = 0;
+  int nKey = 0;
+#endif
 
   /* In normal use, each TCL interpreter runs in a single thread.  So
   ** by default, we can turn of mutexing on SQLite database connections.
@@ -2960,7 +2960,9 @@ static int DbMain(void *cd, Tcl_Interp *interp, int objc,Tcl_Obj *const*objv){
   for(i=3; i+1<objc; i+=2){
     zArg = Tcl_GetString(objv[i]);
     if( strcmp(zArg,"-key")==0 ){
+#ifdef SQLITE_HAS_CODEC
       pKey = Tcl_GetByteArrayFromObj(objv[i+1], &nKey);
+#endif
     }else if( strcmp(zArg, "-vfs")==0 ){
       zVfs = Tcl_GetString(objv[i+1]);
     }else if( strcmp(zArg, "-readonly")==0 ){
diff --git a/src/update.c b/src/update.c
index 2b5efff37..1e3052218 100644
--- a/src/update.c
+++ b/src/update.c
@@ -356,6 +356,7 @@ void sqlite3Update(
       }
     }
     for(i=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, i++){
+      assert( aRegIdx );
       if( openAll || aRegIdx[i]>0 ){
         KeyInfo *pKey = sqlite3IndexKeyinfo(pParse, pIdx);
         sqlite3VdbeAddOp4(v, OP_OpenWrite, iCur+i+1, pIdx->tnum, iDb,
@@ -529,6 +530,7 @@ void sqlite3Update(
 
   /* Close all tables */
   for(i=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, i++){
+    assert( aRegIdx );
     if( openAll || aRegIdx[i]>0 ){
       sqlite3VdbeAddOp2(v, OP_Close, iCur+i+1, 0);
     }
diff --git a/src/vdbe.c b/src/vdbe.c
index 4f7fd6bbe..91e25bafc 100644
--- a/src/vdbe.c
+++ b/src/vdbe.c
@@ -2178,7 +2178,7 @@ case OP_Column: {
       zRec = (char*)pC->aRow;
     }else if( pC->isIndex ){
       assert( sqlite3BtreeCursorIsValid(pCrsr) );
-      rc = sqlite3BtreeKeySize(pCrsr, &payloadSize64);
+      VVA_ONLY(rc =) sqlite3BtreeKeySize(pCrsr, &payloadSize64);
       assert( rc==SQLITE_OK );   /* True because of CursorMoveto() call above */
       /* sqlite3BtreeParseCellPtr() uses getVarint32() to extract the
       ** payload size, so it is impossible for payloadSize64 to be
@@ -2187,7 +2187,7 @@ case OP_Column: {
       payloadSize = (u32)payloadSize64;
     }else{
       assert( sqlite3BtreeCursorIsValid(pCrsr) );
-      rc = sqlite3BtreeDataSize(pCrsr, &payloadSize);
+      VVA_ONLY(rc =) sqlite3BtreeDataSize(pCrsr, &payloadSize);
       assert( rc==SQLITE_OK );   /* DataSize() cannot fail */
     }
   }else if( ALWAYS(pC->pseudoTableReg>0) ){
@@ -4191,14 +4191,14 @@ case OP_RowData: {
 
   if( pC->isIndex ){
     assert( !pC->isTable );
-    rc = sqlite3BtreeKeySize(pCrsr, &n64);
+    VVA_ONLY(rc =) sqlite3BtreeKeySize(pCrsr, &n64);
     assert( rc==SQLITE_OK );    /* True because of CursorMoveto() call above */
     if( n64>db->aLimit[SQLITE_LIMIT_LENGTH] ){
       goto too_big;
     }
     n = (u32)n64;
   }else{
-    rc = sqlite3BtreeDataSize(pCrsr, &n);
+    VVA_ONLY(rc =) sqlite3BtreeDataSize(pCrsr, &n);
     assert( rc==SQLITE_OK );    /* DataSize() cannot fail */
     if( n>(u32)db->aLimit[SQLITE_LIMIT_LENGTH] ){
       goto too_big;
diff --git a/src/vdbeaux.c b/src/vdbeaux.c
index 9de4fe04f..15b28ab90 100644
--- a/src/vdbeaux.c
+++ b/src/vdbeaux.c
@@ -781,30 +781,29 @@ void sqlite3VdbeChangeP4(Vdbe *p, int addr, const char *zP4, int n){
 ** makes the code easier to read during debugging.  None of this happens
 ** in a production build.
 */
-void sqlite3VdbeComment(Vdbe *p, const char *zFormat, ...){
-  va_list ap;
-  if( !p ) return;
+static void vdbeVComment(Vdbe *p, const char *zFormat, va_list ap){
   assert( p->nOp>0 || p->aOp==0 );
   assert( p->aOp==0 || p->aOp[p->nOp-1].zComment==0 || p->db->mallocFailed );
   if( p->nOp ){
-    char **pz = &p->aOp[p->nOp-1].zComment;
+    assert( p->aOp );
+    sqlite3DbFree(p->db, p->aOp[p->nOp-1].zComment);
+    p->aOp[p->nOp-1].zComment = sqlite3VMPrintf(p->db, zFormat, ap);
+  }
+}
+void sqlite3VdbeComment(Vdbe *p, const char *zFormat, ...){
+  va_list ap;
+  if( p ){
     va_start(ap, zFormat);
-    sqlite3DbFree(p->db, *pz);
-    *pz = sqlite3VMPrintf(p->db, zFormat, ap);
+    vdbeVComment(p, zFormat, ap);
     va_end(ap);
   }
 }
 void sqlite3VdbeNoopComment(Vdbe *p, const char *zFormat, ...){
   va_list ap;
-  if( !p ) return;
-  sqlite3VdbeAddOp0(p, OP_Noop);
-  assert( p->nOp>0 || p->aOp==0 );
-  assert( p->aOp==0 || p->aOp[p->nOp-1].zComment==0 || p->db->mallocFailed );
-  if( p->nOp ){
-    char **pz = &p->aOp[p->nOp-1].zComment;
+  if( p ){
+    sqlite3VdbeAddOp0(p, OP_Noop);
     va_start(ap, zFormat);
-    sqlite3DbFree(p->db, *pz);
-    *pz = sqlite3VMPrintf(p->db, zFormat, ap);
+    vdbeVComment(p, zFormat, ap);
     va_end(ap);
   }
 }
@@ -3064,7 +3063,7 @@ int sqlite3VdbeIdxRowid(sqlite3 *db, BtCursor *pCur, i64 *rowid){
   ** this code can safely assume that nCellKey is 32-bits  
   */
   assert( sqlite3BtreeCursorIsValid(pCur) );
-  rc = sqlite3BtreeKeySize(pCur, &nCellKey);
+  VVA_ONLY(rc =) sqlite3BtreeKeySize(pCur, &nCellKey);
   assert( rc==SQLITE_OK );     /* pCur is always valid so KeySize cannot fail */
   assert( (nCellKey & SQLITE_MAX_U32)==(u64)nCellKey );
 
@@ -3139,7 +3138,7 @@ int sqlite3VdbeIdxKeyCompare(
   Mem m;
 
   assert( sqlite3BtreeCursorIsValid(pCur) );
-  rc = sqlite3BtreeKeySize(pCur, &nCellKey);
+  VVA_ONLY(rc =) sqlite3BtreeKeySize(pCur, &nCellKey);
   assert( rc==SQLITE_OK );    /* pCur is always valid so KeySize cannot fail */
   /* nCellKey will always be between 0 and 0xffffffff because of the say
   ** that btreeParseCellPtr() and sqlite3GetVarint32() are implemented */
diff --git a/src/wal.c b/src/wal.c
index 3bc42ffb1..f2b318714 100644
--- a/src/wal.c
+++ b/src/wal.c
@@ -2343,7 +2343,7 @@ int sqlite3WalRead(
     int sz;
     i64 iOffset;
     sz = pWal->hdr.szPage;
-    sz = (pWal->hdr.szPage&0xfe00) + ((pWal->hdr.szPage&0x0001)<<16);
+    sz = (sz&0xfe00) + ((sz&0x0001)<<16);
     testcase( sz<=32768 );
     testcase( sz>=65536 );
     iOffset = walFrameOffset(iRead, sz) + WAL_FRAME_HDRSIZE;
diff --git a/src/where.c b/src/where.c
index 3c0244e68..f962d6f35 100644
--- a/src/where.c
+++ b/src/where.c
@@ -4896,7 +4896,8 @@ WhereInfo *sqlite3WhereBegin(
     WHERETRACE(("*** Optimizer selects table %d for loop %d"
                 " with cost=%g and nRow=%g\n",
                 bestJ, pLevel-pWInfo->a, bestPlan.rCost, bestPlan.plan.nRow));
-    if( (bestPlan.plan.wsFlags & WHERE_ORDERBY)!=0 ){
+    /* The ALWAYS() that follows was added to hush up clang scan-build */
+    if( (bestPlan.plan.wsFlags & WHERE_ORDERBY)!=0 && ALWAYS(ppOrderBy) ){
       *ppOrderBy = 0;
     }
     if( (bestPlan.plan.wsFlags & WHERE_DISTINCT)!=0 ){