Use symbolic names XN_ROWID and XN_EXPR in place of the (-1) and (-2)

magic numbers in Index.aiColumn[].  Add asserts to help verify that
Index.aiColumn[] is always used correctly.  Fix one place in FK processing
where Index.aiColumn[] was not being used correctly.

FossilOrigin-Name: 7d272aa62cd4cbbf4b5d04e3b918de27671e8301

1 files changed, 6 insertions, 6 deletions

diff --git a/src/expr.c b/src/expr.c
index 3141cd9db..b52e814f3 100644
--- a/src/expr.c
+++ b/src/expr.c
@@ -2443,15 +2443,15 @@ void sqlite3ExprCodeLoadIndexColumn(
   int regOut      /* Store the index column value in this register */
 ){
   i16 iTabCol = pIdx->aiColumn[iIdxCol];
-  if( iTabCol>=(-1) ){
+  if( iTabCol==XN_EXPR ){
+    assert( pIdx->aColExpr );
+    assert( pIdx->aColExpr->nExpr>iIdxCol );
+    pParse->iSelfTab = iTabCur;
+    sqlite3ExprCode(pParse, pIdx->aColExpr->a[iIdxCol].pExpr, regOut);
+  }else{
     sqlite3ExprCodeGetColumnOfTable(pParse->pVdbe, pIdx->pTable, iTabCur,
                                     iTabCol, regOut);
-    return;
   }
-  assert( pIdx->aColExpr );
-  assert( pIdx->aColExpr->nExpr>iIdxCol );
-  pParse->iSelfTab = iTabCur;
-  sqlite3ExprCode(pParse, pIdx->aColExpr->a[iIdxCol].pExpr, regOut);
 }
 
 /*