SQLite

  for(p=pToken; p; p=pNext){
    pNext = p->pNext;
    sqlite3DbFree(db, p);
  }
}

/*
** Search the Parse object passed as the first argument for a RenameToken
** Return the RenameToken object associated with parse tree element pPtr,
** object associated with parse tree element pPtr. If found, remove it
** or a NULL pointer if not found.  The RenameToken object returned is
** removed from the list of RenameToken objects attached to the Parse
** from the Parse object and add it to the list maintained by the
** object and the caller becomes the new owner of the RenameToken object
** Hence, the caller assumes responsibility for freeing the returned
** RenameToken object.
** RenameCtx object passed as the second argument.
*/
static RenameToken *renameTokenFind(Parse *pParse, void *pPtr){
static void renameTokenFind(Parse *pParse, struct RenameCtx *pCtx, void *pPtr){
  RenameToken **pp;
  for(pp=&pParse->pRename; (*pp); pp=&(*pp)->pNext){
    if( (*pp)->p==pPtr ){
      RenameToken *pToken = *pp;
      *pp = pToken->pNext;
      pToken->pNext = 0;
      return pToken;
      pToken->pNext = pCtx->pList;
      pCtx->pList = pToken;
      pCtx->nList++;
      break;
    }
  }
  return 0;
}


/*
** This is a Walker expression callback.
**
** For every TK_COLUMN node in the expression tree, search to see
** if the column being references is the column being renamed by an
** ALTER TABLE statement.  If it is, then attach its associated
** RenameToken object to the list of RenameToken objects being
** constructed in RenameCtx object at pWalker->u.pRename.
*/
static int renameColumnExprCb(Walker *pWalker, Expr *pExpr){
  struct RenameCtx *p = pWalker->u.pRename;
  if( pExpr->op==TK_COLUMN && pExpr->iColumn==p->iCol ){
    RenameToken *pTok = renameTokenFind(pWalker->pParse, (void*)pExpr);
    renameTokenFind(pWalker->pParse, p, (void*)pExpr);
    if( pTok ){
      pTok->pNext = p->pList;
      p->pList = pTok;
      p->nList++;
    }
  }
  return WRC_Continue;
}

/*
** The RenameCtx contains a list of tokens that reference a column that
** is being renamed by an ALTER TABLE statement.  Return the "first"

  sWalker.xExprCallback = renameColumnExprCb;
  sWalker.u.pRename = &sCtx;

  if( sParse.pNewTable ){
    int bFKOnly = sqlite3_stricmp(zTable, sParse.pNewTable->zName);
    FKey *pFKey;
    if( bFKOnly==0 ){
      sCtx.pList = renameTokenFind(
          &sParse, (void*)sParse.pNewTable->aCol[sCtx.iCol].zName
      renameTokenFind(
          &sParse, &sCtx, (void*)sParse.pNewTable->aCol[sCtx.iCol].zName
      );
      sCtx.nList = 1;
      assert( sCtx.iCol>=0 );
      if( sParse.pNewTable->iPKey==sCtx.iCol ){
        renameTokenFind(&sParse, &sCtx, (void*)&sParse.pNewTable->iPKey);
        sCtx.iCol = -1;
      }
      sqlite3WalkExprList(&sWalker, sParse.pNewTable->pCheck);
      for(pIdx=sParse.pNewTable->pIndex; pIdx; pIdx=pIdx->pNext){
        sqlite3WalkExprList(&sWalker, pIdx->aColExpr);
      }
    }

    for(pFKey=sParse.pNewTable->pFKey; pFKey; pFKey=pFKey->pNextFrom){
      for(i=0; i<pFKey->nCol; i++){
        RenameToken *pTok = 0;
        if( bFKOnly==0 && pFKey->aCol[i].iFrom==sCtx.iCol ){
          pTok = renameTokenFind(&sParse, (void*)&pFKey->aCol[i]);
          renameTokenFind(&sParse, &sCtx, (void*)&pFKey->aCol[i]);
          if( pTok ){
            pTok->pNext = sCtx.pList;
            sCtx.pList = pTok;
            sCtx.nList++;
          }
        }
        if( 0==sqlite3_stricmp(pFKey->zTo, zTable)
         && 0==sqlite3_stricmp(pFKey->aCol[i].zCol, zOld)
        ){
          pTok = renameTokenFind(&sParse, (void*)pFKey->aCol[i].zCol);
          renameTokenFind(&sParse, &sCtx, (void*)pFKey->aCol[i].zCol);
          pTok->pNext = sCtx.pList;
          sCtx.pList = pTok;
          sCtx.nList++;
        }
      }
    }
  }else{
    sqlite3WalkExprList(&sWalker, sParse.pNewIndex->aColExpr);
    sqlite3WalkExpr(&sWalker, sParse.pNewIndex->pPartIdxWhere);
  }

    }
  }
  if( nTerm==1
   && pCol
   && sqlite3StrICmp(sqlite3ColumnType(pCol,""), "INTEGER")==0
   && sortOrder!=SQLITE_SO_DESC
  ){
    if( IN_RENAME_COLUMN && pList ){
      sqlite3MoveRenameToken(pParse, &pTab->iPKey, pList->a[0].pExpr);
    }
    pTab->iPKey = iCol;
    pTab->keyConf = (u8)onError;
    assert( autoInc==0 || autoInc==1 );
    pTab->tabFlags |= autoInc*TF_Autoincrement;
    if( pList ) pParse->iPkSortOrder = pList->a[0].sortOrder;
  }else if( autoInc ){
#ifndef SQLITE_OMIT_AUTOINCREMENT

    {{CREATE TABLE t1(a, d, c)} {CREATE INDEX t1i ON t1(d, c)}}

 12 {CREATE TABLE t1(a, b, c);   CREATE INDEX t1i ON t1(b+b+b+b, c) WHERE b>0}
    {{CREATE TABLE t1(a, d, c)} {CREATE INDEX t1i ON t1(d+d+d+d, c) WHERE d>0}}

 13 {CREATE TABLE t1(a, b, c, FOREIGN KEY (b) REFERENCES t2)}
    {CREATE TABLE t1(a, d, c, FOREIGN KEY (d) REFERENCES t2)}

 15 {CREATE TABLE t1(a INTEGER, b INTEGER, c BLOB, PRIMARY KEY(b))}
    {CREATE TABLE t1(a INTEGER, d INTEGER, c BLOB, PRIMARY KEY(d))}

 16 {CREATE TABLE t1(a INTEGER, b INTEGER PRIMARY KEY, c BLOB)}
    {CREATE TABLE t1(a INTEGER, d INTEGER PRIMARY KEY, c BLOB)}

} {
  reset_db
  do_execsql_test 1.$tn.0 $before

  do_execsql_test 1.$tn.1 {
    INSERT INTO t1 VALUES(1, 2, 3);