Fix a crash in new ALTER TABLE code that could follow an OOM.

FossilOrigin-Name: 6f1f2a0a9cd75ca43b81cc325296b843ccefe6f8040da8f2e873f49928423f10

1 files changed, 12 insertions, 11 deletions

diff --git a/src/alter.c b/src/alter.c
index c1a8e2476..e5f1eb315 100644
--- a/src/alter.c
+++ b/src/alter.c
@@ -812,18 +812,19 @@ static void renameWalkWith(Walker *pWalker, Select *pSelect){
     assert( pWith->nCte>0 );
     assert( (pWith->a[0].pSelect->selFlags & SF_Expanded)==0 );
     pCopy = sqlite3WithDup(pParse->db, pWith);
-    sqlite3WithPush(pParse, pCopy, 1);
-
-    for(i=0; i<pWith->nCte; i++){
-      Select *p = pWith->a[i].pSelect;
-      NameContext sNC;
-      memset(&sNC, 0, sizeof(sNC));
-      sNC.pParse = pParse;
-      sqlite3SelectPrep(sNC.pParse, p, &sNC);
-      sqlite3WalkSelect(pWalker, p);
-      sqlite3RenameExprlistUnmap(pParse, pWith->a[i].pCols);
+    if( pCopy ){
+      sqlite3WithPush(pParse, pCopy, 1);
+      for(i=0; i<pWith->nCte; i++){
+        Select *p = pWith->a[i].pSelect;
+        NameContext sNC;
+        memset(&sNC, 0, sizeof(sNC));
+        sNC.pParse = pParse;
+        sqlite3SelectPrep(sNC.pParse, p, &sNC);
+        sqlite3WalkSelect(pWalker, p);
+        sqlite3RenameExprlistUnmap(pParse, pWith->a[i].pCols);
+      }
+      pParse->pWith = pCopy->pOuter;
     }
-    pParse->pWith = pCopy->pOuter;
   }
 }