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Overview
Comment:Not only date/time functions, but also functions like sqlite_version() and changes() need to be prohibited from use inside of indexes.
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Timelines: family | ancestors | descendants | both | index-expr
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SHA1: 487131303980f15dd5e1b6695b4f29efda229eb8
User & Date: drh 2015-08-31 21:16:36
Context
2015-08-31
23:09
Fix a bug in error reporting when a UNIQUE index on expressions fails its uniqueness test. check-in: 5a2c0e90 user: drh tags: index-expr
21:16
Not only date/time functions, but also functions like sqlite_version() and changes() need to be prohibited from use inside of indexes. check-in: 48713130 user: drh tags: index-expr
19:38
Always assume that indexed expressions can generate a NULL. Get indexed expressions working for the case of two or more expressions in the same index. check-in: cc60321a user: drh tags: index-expr
Changes
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Changes to src/func.c.

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    FUNCTION2(ifnull,            2, 0, 0, noopFunc,  SQLITE_FUNC_COALESCE),
    FUNCTION2(unlikely,          1, 0, 0, noopFunc,  SQLITE_FUNC_UNLIKELY),
    FUNCTION2(likelihood,        2, 0, 0, noopFunc,  SQLITE_FUNC_UNLIKELY),
    FUNCTION2(likely,            1, 0, 0, noopFunc,  SQLITE_FUNC_UNLIKELY),
    VFUNCTION(random,            0, 0, 0, randomFunc       ),
    VFUNCTION(randomblob,        1, 0, 0, randomBlob       ),
    FUNCTION(nullif,             2, 0, 1, nullifFunc       ),
    FUNCTION(sqlite_version,     0, 0, 0, versionFunc      ),
    FUNCTION(sqlite_source_id,   0, 0, 0, sourceidFunc     ),
    FUNCTION(sqlite_log,         2, 0, 0, errlogFunc       ),
#if SQLITE_USER_AUTHENTICATION
    FUNCTION(sqlite_crypt,       2, 0, 0, sqlite3CryptFunc ),
#endif
#ifndef SQLITE_OMIT_COMPILEOPTION_DIAGS
    FUNCTION(sqlite_compileoption_used,1, 0, 0, compileoptionusedFunc  ),
    FUNCTION(sqlite_compileoption_get, 1, 0, 0, compileoptiongetFunc  ),
#endif /* SQLITE_OMIT_COMPILEOPTION_DIAGS */
    FUNCTION(quote,              1, 0, 0, quoteFunc        ),
    VFUNCTION(last_insert_rowid, 0, 0, 0, last_insert_rowid),
    VFUNCTION(changes,           0, 0, 0, changes          ),
    VFUNCTION(total_changes,     0, 0, 0, total_changes    ),
    FUNCTION(replace,            3, 0, 0, replaceFunc      ),
    FUNCTION(zeroblob,           1, 0, 0, zeroblobFunc     ),
  #ifdef SQLITE_SOUNDEX
    FUNCTION(soundex,            1, 0, 0, soundexFunc      ),
  #endif
  #ifndef SQLITE_OMIT_LOAD_EXTENSION
    FUNCTION(load_extension,     1, 0, 0, loadExt          ),
    FUNCTION(load_extension,     2, 0, 0, loadExt          ),
  #endif
    AGGREGATE(sum,               1, 0, 0, sumStep,         sumFinalize    ),
    AGGREGATE(total,             1, 0, 0, sumStep,         totalFinalize    ),
    AGGREGATE(avg,               1, 0, 0, sumStep,         avgFinalize    ),
    AGGREGATE2(count,            0, 0, 0, countStep,       countFinalize,
               SQLITE_FUNC_COUNT  ),
    AGGREGATE(count,             1, 0, 0, countStep,       countFinalize  ),







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    FUNCTION2(ifnull,            2, 0, 0, noopFunc,  SQLITE_FUNC_COALESCE),
    FUNCTION2(unlikely,          1, 0, 0, noopFunc,  SQLITE_FUNC_UNLIKELY),
    FUNCTION2(likelihood,        2, 0, 0, noopFunc,  SQLITE_FUNC_UNLIKELY),
    FUNCTION2(likely,            1, 0, 0, noopFunc,  SQLITE_FUNC_UNLIKELY),
    VFUNCTION(random,            0, 0, 0, randomFunc       ),
    VFUNCTION(randomblob,        1, 0, 0, randomBlob       ),
    FUNCTION(nullif,             2, 0, 1, nullifFunc       ),
    DFUNCTION(sqlite_version,    0, 0, 0, versionFunc      ),
    DFUNCTION(sqlite_source_id,  0, 0, 0, sourceidFunc     ),
    FUNCTION(sqlite_log,         2, 0, 0, errlogFunc       ),
#if SQLITE_USER_AUTHENTICATION
    FUNCTION(sqlite_crypt,       2, 0, 0, sqlite3CryptFunc ),
#endif
#ifndef SQLITE_OMIT_COMPILEOPTION_DIAGS
    DFUNCTION(sqlite_compileoption_used,1, 0, 0, compileoptionusedFunc  ),
    DFUNCTION(sqlite_compileoption_get, 1, 0, 0, compileoptiongetFunc  ),
#endif /* SQLITE_OMIT_COMPILEOPTION_DIAGS */
    FUNCTION(quote,              1, 0, 0, quoteFunc        ),
    VFUNCTION(last_insert_rowid, 0, 0, 0, last_insert_rowid),
    VFUNCTION(changes,           0, 0, 0, changes          ),
    VFUNCTION(total_changes,     0, 0, 0, total_changes    ),
    FUNCTION(replace,            3, 0, 0, replaceFunc      ),
    FUNCTION(zeroblob,           1, 0, 0, zeroblobFunc     ),
  #ifdef SQLITE_SOUNDEX
    FUNCTION(soundex,            1, 0, 0, soundexFunc      ),
  #endif
  #ifndef SQLITE_OMIT_LOAD_EXTENSION
    VFUNCTION(load_extension,    1, 0, 0, loadExt          ),
    VFUNCTION(load_extension,    2, 0, 0, loadExt          ),
  #endif
    AGGREGATE(sum,               1, 0, 0, sumStep,         sumFinalize    ),
    AGGREGATE(total,             1, 0, 0, sumStep,         totalFinalize    ),
    AGGREGATE(avg,               1, 0, 0, sumStep,         avgFinalize    ),
    AGGREGATE2(count,            0, 0, 0, countStep,       countFinalize,
               SQLITE_FUNC_COUNT  ),
    AGGREGATE(count,             1, 0, 0, countStep,       countFinalize  ),

Changes to src/resolve.c.

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    ExprSetProperty(p, EP_Resolved);
  }
  return p;
}

/*
** Report an error that an expression is not valid for some set of
** pNC->ncFlags values determined by validMask.  If 
*/
static void notValid(
  Parse *pParse,       /* Leave error message here */
  NameContext *pNC,    /* The name context */
  const char *zMsg,    /* Type of error */
  int validMask,       /* Set of contexts for which prohibited */
  int okForInit        /* No error if pParse->db->init.busy is true */
){
  assert( (validMask&~(NC_IsCheck|NC_PartIdx|NC_IdxExpr))==0 );
  if( (pNC->ncFlags & validMask)!=0 
   && (pParse->db->init.busy==0 || !okForInit)
  ){
    const char *zIn = "partial index WHERE clauses";
    if( pNC->ncFlags & NC_IdxExpr )      zIn = "index expressions";
#ifndef SQLITE_OMIT_CHECK
    else if( pNC->ncFlags & NC_IsCheck ) zIn = "CHECK constraints";
#endif
    sqlite3ErrorMsg(pParse, "%s prohibited in %s", zMsg, zIn);
  }
................................................................................
    case TK_DOT: {
      const char *zColumn;
      const char *zTable;
      const char *zDb;
      Expr *pRight;

      /* if( pSrcList==0 ) break; */
      notValid(pParse, pNC, "the \".\" operator", NC_IdxExpr, 0);
      /*notValid(pParse, pNC, "the \".\" operator", NC_PartIdx|NC_IsCheck, 1);*/
      pRight = pExpr->pRight;
      if( pRight->op==TK_ID ){
        zDb = 0;
        zTable = pExpr->pLeft->u.zToken;
        zColumn = pRight->u.zToken;
      }else{
................................................................................
      int auth;                   /* Authorization to use the function */
      int nId;                    /* Number of characters in function name */
      const char *zId;            /* The function name. */
      FuncDef *pDef;              /* Information about the function */
      u8 enc = ENC(pParse->db);   /* The database encoding */

      assert( !ExprHasProperty(pExpr, EP_xIsSelect) );
      notValid(pParse, pNC, "functions", NC_PartIdx, 0);
      zId = pExpr->u.zToken;
      nId = sqlite3Strlen30(zId);
      pDef = sqlite3FindFunction(pParse->db, zId, nId, n, enc, 0);
      if( pDef==0 ){
        pDef = sqlite3FindFunction(pParse->db, zId, nId, -2, enc, 0);
        if( pDef==0 ){
          no_such_func = 1;
................................................................................
                                    pDef->zName);
            pNC->nErr++;
          }
          pExpr->op = TK_NULL;
          return WRC_Prune;
        }
#endif
        if( pDef->funcFlags & (SQLITE_FUNC_CONSTANT|SQLITE_FUNC_DATETIME) ){
          /* For the purposes of the EP_ConstFunc flag, date and time
          ** functions are considered constant because the the time does
          ** not change for the duration of a query. */
          ExprSetProperty(pExpr,EP_ConstFunc);
        }
        if( (pDef->funcFlags & SQLITE_FUNC_CONSTANT)==0 ){
          /* DATETIME functions are considered non-deterministic because of
          ** the 'now' capability */
          notValid(pParse, pNC, "non-deterministic functions", NC_IdxExpr, 0);
        }
      }
      if( is_agg && (pNC->ncFlags & NC_AllowAgg)==0 ){
        sqlite3ErrorMsg(pParse, "misuse of aggregate function %.*s()", nId,zId);
        pNC->nErr++;
        is_agg = 0;
      }else if( no_such_func && pParse->db->init.busy==0 ){
................................................................................
    case TK_SELECT:
    case TK_EXISTS:  testcase( pExpr->op==TK_EXISTS );
#endif
    case TK_IN: {
      testcase( pExpr->op==TK_IN );
      if( ExprHasProperty(pExpr, EP_xIsSelect) ){
        int nRef = pNC->nRef;
        notValid(pParse, pNC, "subqueries", NC_IsCheck|NC_PartIdx|NC_IdxExpr,0);
        sqlite3WalkSelect(pWalker, pExpr->x.pSelect);
        assert( pNC->nRef>=nRef );
        if( nRef!=pNC->nRef ){
          ExprSetProperty(pExpr, EP_VarSelect);
        }
      }
      break;
    }
    case TK_VARIABLE: {
      notValid(pParse, pNC, "parameters", NC_IsCheck|NC_PartIdx|NC_IdxExpr, 0);
      break;
    }
  }
  return (pParse->nErr || pParse->db->mallocFailed) ? WRC_Abort : WRC_Continue;
}

/*







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    ExprSetProperty(p, EP_Resolved);
  }
  return p;
}

/*
** Report an error that an expression is not valid for some set of
** pNC->ncFlags values determined by validMask.
*/
static void notValid(
  Parse *pParse,       /* Leave error message here */
  NameContext *pNC,    /* The name context */
  const char *zMsg,    /* Type of error */
  int validMask        /* Set of contexts for which prohibited */

){
  assert( (validMask&~(NC_IsCheck|NC_PartIdx|NC_IdxExpr))==0 );
  if( (pNC->ncFlags & validMask)!=0 ){


    const char *zIn = "partial index WHERE clauses";
    if( pNC->ncFlags & NC_IdxExpr )      zIn = "index expressions";
#ifndef SQLITE_OMIT_CHECK
    else if( pNC->ncFlags & NC_IsCheck ) zIn = "CHECK constraints";
#endif
    sqlite3ErrorMsg(pParse, "%s prohibited in %s", zMsg, zIn);
  }
................................................................................
    case TK_DOT: {
      const char *zColumn;
      const char *zTable;
      const char *zDb;
      Expr *pRight;

      /* if( pSrcList==0 ) break; */
      notValid(pParse, pNC, "the \".\" operator", NC_IdxExpr);
      /*notValid(pParse, pNC, "the \".\" operator", NC_PartIdx|NC_IsCheck, 1);*/
      pRight = pExpr->pRight;
      if( pRight->op==TK_ID ){
        zDb = 0;
        zTable = pExpr->pLeft->u.zToken;
        zColumn = pRight->u.zToken;
      }else{
................................................................................
      int auth;                   /* Authorization to use the function */
      int nId;                    /* Number of characters in function name */
      const char *zId;            /* The function name. */
      FuncDef *pDef;              /* Information about the function */
      u8 enc = ENC(pParse->db);   /* The database encoding */

      assert( !ExprHasProperty(pExpr, EP_xIsSelect) );
      notValid(pParse, pNC, "functions", NC_PartIdx);
      zId = pExpr->u.zToken;
      nId = sqlite3Strlen30(zId);
      pDef = sqlite3FindFunction(pParse->db, zId, nId, n, enc, 0);
      if( pDef==0 ){
        pDef = sqlite3FindFunction(pParse->db, zId, nId, -2, enc, 0);
        if( pDef==0 ){
          no_such_func = 1;
................................................................................
                                    pDef->zName);
            pNC->nErr++;
          }
          pExpr->op = TK_NULL;
          return WRC_Prune;
        }
#endif
        if( pDef->funcFlags & (SQLITE_FUNC_CONSTANT|SQLITE_FUNC_VARYING) ){
          /* For the purposes of the EP_ConstFunc flag, date and time
          ** functions and other functions that change slowly are considered
          ** constant because they are constant for the duration of one query */
          ExprSetProperty(pExpr,EP_ConstFunc);
        }
        if( (pDef->funcFlags & SQLITE_FUNC_CONSTANT)==0 ){
          /* DATETIME functions are considered non-deterministic because of
          ** the 'now' capability */
          notValid(pParse, pNC, "non-deterministic functions", NC_IdxExpr);
        }
      }
      if( is_agg && (pNC->ncFlags & NC_AllowAgg)==0 ){
        sqlite3ErrorMsg(pParse, "misuse of aggregate function %.*s()", nId,zId);
        pNC->nErr++;
        is_agg = 0;
      }else if( no_such_func && pParse->db->init.busy==0 ){
................................................................................
    case TK_SELECT:
    case TK_EXISTS:  testcase( pExpr->op==TK_EXISTS );
#endif
    case TK_IN: {
      testcase( pExpr->op==TK_IN );
      if( ExprHasProperty(pExpr, EP_xIsSelect) ){
        int nRef = pNC->nRef;
        notValid(pParse, pNC, "subqueries", NC_IsCheck|NC_PartIdx|NC_IdxExpr);
        sqlite3WalkSelect(pWalker, pExpr->x.pSelect);
        assert( pNC->nRef>=nRef );
        if( nRef!=pNC->nRef ){
          ExprSetProperty(pExpr, EP_VarSelect);
        }
      }
      break;
    }
    case TK_VARIABLE: {
      notValid(pParse, pNC, "parameters", NC_IsCheck|NC_PartIdx|NC_IdxExpr);
      break;
    }
  }
  return (pParse->nErr || pParse->db->mallocFailed) ? WRC_Abort : WRC_Continue;
}

/*

Changes to src/sqliteInt.h.

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#define SQLITE_FUNC_LENGTH   0x0040 /* Built-in length() function */
#define SQLITE_FUNC_TYPEOF   0x0080 /* Built-in typeof() function */
#define SQLITE_FUNC_COUNT    0x0100 /* Built-in count(*) aggregate */
#define SQLITE_FUNC_COALESCE 0x0200 /* Built-in coalesce() or ifnull() */
#define SQLITE_FUNC_UNLIKELY 0x0400 /* Built-in unlikely() function */
#define SQLITE_FUNC_CONSTANT 0x0800 /* Constant inputs give a constant output */
#define SQLITE_FUNC_MINMAX   0x1000 /* True for min() and max() aggregates */
#define SQLITE_FUNC_DATETIME 0x2000 /* Function returns a date and/or time */

/*
** The following three macros, FUNCTION(), LIKEFUNC() and AGGREGATE() are
** used to create the initializers for the FuncDef structures.
**
**   FUNCTION(zName, nArg, iArg, bNC, xFunc)
**     Used to create a scalar function definition of a function zName 
................................................................................
**     argument bNC is true, then the SQLITE_FUNC_NEEDCOLL flag is set.
**
**   VFUNCTION(zName, nArg, iArg, bNC, xFunc)
**     Like FUNCTION except it omits the SQLITE_FUNC_CONSTANT flag.
**
**   DFUNCTION(zName, nArg, iArg, bNC, xFunc)
**     Like FUNCTION except it omits the SQLITE_FUNC_CONSTANT flag and
**     adds the SQLITE_FUNC_DATETIME flag.  Used for date & time functions.


**
**   AGGREGATE(zName, nArg, iArg, bNC, xStep, xFinal)
**     Used to create an aggregate function definition implemented by
**     the C functions xStep and xFinal. The first four parameters
**     are interpreted in the same way as the first 4 parameters to
**     FUNCTION().
**
................................................................................
#define FUNCTION(zName, nArg, iArg, bNC, xFunc) \
  {nArg, SQLITE_FUNC_CONSTANT|SQLITE_UTF8|(bNC*SQLITE_FUNC_NEEDCOLL), \
   SQLITE_INT_TO_PTR(iArg), 0, xFunc, 0, 0, #zName, 0, 0}
#define VFUNCTION(zName, nArg, iArg, bNC, xFunc) \
  {nArg, SQLITE_UTF8|(bNC*SQLITE_FUNC_NEEDCOLL), \
   SQLITE_INT_TO_PTR(iArg), 0, xFunc, 0, 0, #zName, 0, 0}
#define DFUNCTION(zName, nArg, iArg, bNC, xFunc) \
  {nArg, SQLITE_FUNC_DATETIME|SQLITE_UTF8|(bNC*SQLITE_FUNC_NEEDCOLL), \
   SQLITE_INT_TO_PTR(iArg), 0, xFunc, 0, 0, #zName, 0, 0}
#define FUNCTION2(zName, nArg, iArg, bNC, xFunc, extraFlags) \
  {nArg,SQLITE_FUNC_CONSTANT|SQLITE_UTF8|(bNC*SQLITE_FUNC_NEEDCOLL)|extraFlags,\
   SQLITE_INT_TO_PTR(iArg), 0, xFunc, 0, 0, #zName, 0, 0}
#define STR_FUNCTION(zName, nArg, pArg, bNC, xFunc) \
  {nArg, SQLITE_FUNC_CONSTANT|SQLITE_UTF8|(bNC*SQLITE_FUNC_NEEDCOLL), \
   pArg, 0, xFunc, 0, 0, #zName, 0, 0}
#define LIKEFUNC(zName, nArg, arg, flags) \
  {nArg, SQLITE_FUNC_CONSTANT|SQLITE_UTF8|flags, \
   (void *)arg, 0, likeFunc, 0, 0, #zName, 0, 0}
#define AGGREGATE(zName, nArg, arg, nc, xStep, xFinal) \
  {nArg, SQLITE_UTF8|(nc*SQLITE_FUNC_NEEDCOLL), \
   SQLITE_INT_TO_PTR(arg), 0, 0, xStep,xFinal,#zName,0,0}
................................................................................
#define EP_Skip      0x001000 /* COLLATE, AS, or UNLIKELY */
#define EP_Reduced   0x002000 /* Expr struct EXPR_REDUCEDSIZE bytes only */
#define EP_TokenOnly 0x004000 /* Expr struct EXPR_TOKENONLYSIZE bytes only */
#define EP_Static    0x008000 /* Held in memory not obtained from malloc() */
#define EP_MemToken  0x010000 /* Need to sqlite3DbFree() Expr.zToken */
#define EP_NoReduce  0x020000 /* Cannot EXPRDUP_REDUCE this Expr */
#define EP_Unlikely  0x040000 /* unlikely() or likelihood() function */
#define EP_ConstFunc 0x080000 /* A SQLITE_FUNC_CONSTANT or _DATETIME function */
#define EP_CanBeNull 0x100000 /* Can be null despite NOT NULL constraint */
#define EP_Subquery  0x200000 /* Tree contains a TK_SELECT operator */

/*
** Combinations of two or more EP_* flags
*/
#define EP_Propagate (EP_Collate|EP_Subquery) /* Propagate these bits up tree */







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#define SQLITE_FUNC_LENGTH   0x0040 /* Built-in length() function */
#define SQLITE_FUNC_TYPEOF   0x0080 /* Built-in typeof() function */
#define SQLITE_FUNC_COUNT    0x0100 /* Built-in count(*) aggregate */
#define SQLITE_FUNC_COALESCE 0x0200 /* Built-in coalesce() or ifnull() */
#define SQLITE_FUNC_UNLIKELY 0x0400 /* Built-in unlikely() function */
#define SQLITE_FUNC_CONSTANT 0x0800 /* Constant inputs give a constant output */
#define SQLITE_FUNC_MINMAX   0x1000 /* True for min() and max() aggregates */
#define SQLITE_FUNC_VARYING  0x2000 /* Function that change in the long term */

/*
** The following three macros, FUNCTION(), LIKEFUNC() and AGGREGATE() are
** used to create the initializers for the FuncDef structures.
**
**   FUNCTION(zName, nArg, iArg, bNC, xFunc)
**     Used to create a scalar function definition of a function zName 
................................................................................
**     argument bNC is true, then the SQLITE_FUNC_NEEDCOLL flag is set.
**
**   VFUNCTION(zName, nArg, iArg, bNC, xFunc)
**     Like FUNCTION except it omits the SQLITE_FUNC_CONSTANT flag.
**
**   DFUNCTION(zName, nArg, iArg, bNC, xFunc)
**     Like FUNCTION except it omits the SQLITE_FUNC_CONSTANT flag and
**     adds the SQLITE_FUNC_VARYING flag.  Used for date & time functions
**     and functions like sqlite_version() that can change, but not during
**     a single query.
**
**   AGGREGATE(zName, nArg, iArg, bNC, xStep, xFinal)
**     Used to create an aggregate function definition implemented by
**     the C functions xStep and xFinal. The first four parameters
**     are interpreted in the same way as the first 4 parameters to
**     FUNCTION().
**
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#define FUNCTION(zName, nArg, iArg, bNC, xFunc) \
  {nArg, SQLITE_FUNC_CONSTANT|SQLITE_UTF8|(bNC*SQLITE_FUNC_NEEDCOLL), \
   SQLITE_INT_TO_PTR(iArg), 0, xFunc, 0, 0, #zName, 0, 0}
#define VFUNCTION(zName, nArg, iArg, bNC, xFunc) \
  {nArg, SQLITE_UTF8|(bNC*SQLITE_FUNC_NEEDCOLL), \
   SQLITE_INT_TO_PTR(iArg), 0, xFunc, 0, 0, #zName, 0, 0}
#define DFUNCTION(zName, nArg, iArg, bNC, xFunc) \
  {nArg, SQLITE_FUNC_VARYING|SQLITE_UTF8|(bNC*SQLITE_FUNC_NEEDCOLL), \
   SQLITE_INT_TO_PTR(iArg), 0, xFunc, 0, 0, #zName, 0, 0}
#define FUNCTION2(zName, nArg, iArg, bNC, xFunc, extraFlags) \
  {nArg,SQLITE_FUNC_CONSTANT|SQLITE_UTF8|(bNC*SQLITE_FUNC_NEEDCOLL)|extraFlags,\
   SQLITE_INT_TO_PTR(iArg), 0, xFunc, 0, 0, #zName, 0, 0}
#define STR_FUNCTION(zName, nArg, pArg, bNC, xFunc) \
  {nArg, SQLITE_FUNC_VARYING|SQLITE_UTF8|(bNC*SQLITE_FUNC_NEEDCOLL), \
   pArg, 0, xFunc, 0, 0, #zName, 0, 0}
#define LIKEFUNC(zName, nArg, arg, flags) \
  {nArg, SQLITE_FUNC_CONSTANT|SQLITE_UTF8|flags, \
   (void *)arg, 0, likeFunc, 0, 0, #zName, 0, 0}
#define AGGREGATE(zName, nArg, arg, nc, xStep, xFinal) \
  {nArg, SQLITE_UTF8|(nc*SQLITE_FUNC_NEEDCOLL), \
   SQLITE_INT_TO_PTR(arg), 0, 0, xStep,xFinal,#zName,0,0}
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#define EP_Skip      0x001000 /* COLLATE, AS, or UNLIKELY */
#define EP_Reduced   0x002000 /* Expr struct EXPR_REDUCEDSIZE bytes only */
#define EP_TokenOnly 0x004000 /* Expr struct EXPR_TOKENONLYSIZE bytes only */
#define EP_Static    0x008000 /* Held in memory not obtained from malloc() */
#define EP_MemToken  0x010000 /* Need to sqlite3DbFree() Expr.zToken */
#define EP_NoReduce  0x020000 /* Cannot EXPRDUP_REDUCE this Expr */
#define EP_Unlikely  0x040000 /* unlikely() or likelihood() function */
#define EP_ConstFunc 0x080000 /* A SQLITE_FUNC_CONSTANT or _VARYING function */
#define EP_CanBeNull 0x100000 /* Can be null despite NOT NULL constraint */
#define EP_Subquery  0x200000 /* Tree contains a TK_SELECT operator */

/*
** Combinations of two or more EP_* flags
*/
#define EP_Propagate (EP_Collate|EP_Subquery) /* Propagate these bits up tree */