Merge fixes from trunk into the empty-table-optimizations branch

FossilOrigin-Name: 6f98b16d210a9f5b6ca4b4599e3dab3263eddbae7c70ddbcabf988f4a1014e8b

src/btree.c

@@ -1929,10 +1929,10 @@ static int freeSpace(MemPage *pPage, int iStart, int iSize){
   assert( pPage->pBt!=0 );
   assert( sqlite3PagerIswriteable(pPage->pDbPage) );
   assert( CORRUPT_DB || iStart>=pPage->hdrOffset+6+pPage->childPtrSize );
-  assert( CORRUPT_DB || iEnd <= pPage->pBt->usableSize );
+  assert( CORRUPT_DB || iEnd <= (int)pPage->pBt->usableSize );
   assert( sqlite3_mutex_held(pPage->pBt->mutex) );
   assert( iSize>=4 );   /* Minimum cell size is 4 */
-  assert( CORRUPT_DB || iStart<=pPage->pBt->usableSize-4 );
+  assert( CORRUPT_DB || iStart<=(int)pPage->pBt->usableSize-4 );
 
   /* The list of freeblocks must be in ascending order.  Find the
   ** spot on the list where iStart should be inserted.

src/expr.c

@@ -2428,6 +2428,7 @@ static int exprComputeOperands(
     VdbeComment((v, "skip left operand"));
     VdbeCoverage(v);
   }else{
+    r2 = 0; /* Silence a false-positive uninit-var warning in MSVC */
     addrIsNull = 0;
   }
   r1 = sqlite3ExprCodeTemp(pParse, pExpr->pLeft, pFree1);

src/whereexpr.c

@@ -1697,7 +1697,7 @@ void SQLITE_NOINLINE sqlite3WhereAddLimit(WhereClause *pWC, Select *p){
         WhereTerm *pParent = &pWC->a[ pWC->a[ii].iParent ];
         if( pParent->leftCursor==iCsr
          && pParent->prereqRight==0
-         && ALWAYS(pParent->nChild==1)
+         && pParent->nChild==1
         ){
           continue;
         }