chore: audit cleanup — remove orphan parser + dead TSqlIndex methods

Opus 4.7 audit of the codebase surfaced several items that Opus 4.6
sessions left behind. This pass removes what's definitively dead and
fixes one trivial defensive bug; the real logic bugs (transaction
ordering, missing RunUpdate/RunDelete validation) come in a separate
commit.

Deletions:

- `_FiveSql2/src/TSqlParser_orig.prg` (1173 lines) — superseded by
  `TSqlParser2.prg` (Pratt). Production never instantiates the old
  parser; the only callers were the comparison/benchmark test files
  also being removed.
- `_FiveSql2/test/test_parser_cmp.prg` — compared orig vs Pratt AST,
  useless now that orig is gone.
- `_FiveSql2/test/bench_parser.prg` — benched both, same reason.
- `_FiveSql2/Makefile` `test_cmp:` and `bench:` targets referenced
  the removed files.
- `TSqlIndex.prg` methods `ApplyScope`, `ClearScope`, `ApplySeek`,
  `IndexInfo`, `CreateTempIndex`, `DropTempIndex` — each declared in
  the class header and implemented (~165 lines total) but zero
  callers anywhere in `_FiveSql2/` or `hbrtl/`. Class declarations
  removed alongside the bodies.

Small fixes:

- `TSqlDDL.prg:179-180` stale comment claiming Five doesn't support
  `@byref` — false since commit e95afad (2026-04-13) wired @byref
  via RefCell. The same method uses @nPos correctly elsewhere.
- `hbrt/class.go:tryBinaryOp` defensive nil-check on AsArray().
  IsObject() checks the type tag; a corrupted Value with tag=Object
  but ptr=nil would crash on `.Class`. Correct construction paths
  never hit this, but the guard is cheap.

Compat tests: FiveSql2 43/43, Harbour compat 56/56, Go test ALL PASS.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

_FiveSql2/Makefile

@@ -68,12 +68,6 @@ test_challenge: $(OUTDIR)
 test_extreme: $(OUTDIR)
 	$(HB) $(TESTDIR)/test_sql_extreme.prg $(SOURCES) -o$(OUTDIR)/test_extreme $(HBFLAGS)
 
-test_cmp: $(OUTDIR)
-	$(HB) $(TESTDIR)/test_parser_cmp.prg $(SRCDIR)/TSqlParser2.prg $(SRCDIR)/TSqlLexer.prg $(SRCDIR)/TSqlExpr.prg $(SRCDIR)/TSqlFunc.prg $(SRCDIR)/FiveSqlDef.ch -o$(OUTDIR)/test_cmp $(HBFLAGS)
-
-bench: $(OUTDIR)
-	$(HB) $(TESTDIR)/bench_parser.prg $(SRCDIR)/TSqlParser2.prg $(SRCDIR)/TSqlLexer.prg $(SRCDIR)/TSqlExpr.prg $(SRCDIR)/TSqlFunc.prg $(SRCDIR)/FiveSqlDef.ch -o$(OUTDIR)/bench_parser $(HBFLAGS)
-
 # ============================================================================
 # Run tests
 # ============================================================================

_FiveSql2/src/TSqlDDL.prg

@@ -176,8 +176,7 @@ METHOD CreateTable( aTokens, nPos ) CLASS TSqlDDL
             LOOP
          ENDIF
 
-         /* CHECK constraint (table-level) — inline parens extraction
+         /* CHECK constraint (table-level) — inline parens extraction. */
-          * because Five does not support pass-by-reference (@nPos) */
          IF ::DDL_IsKW( aTokens, nPos, "CHECK" )
             nPos++
             cCheckExpr := ""

_FiveSql2/src/TSqlIndex.prg

@@ -30,17 +30,11 @@ CLASS TSqlIndex
    METHOD ListTags( nWA )
    METHOD FindBestTag( nWA, cField )
    METHOD FindCompoundTag( nWA, aFields )
-   METHOD ApplyScope( nWA, cField, xLow, xHigh )
-   METHOD ClearScope( nWA )
-   METHOD ApplySeek( nWA, cField, xValue )
    METHOD BuildKey( nWA, xValue )
    METHOD MatchOrderByTag( nWA, aOrderBy, aFieldNames )
    METHOD TryIndexScan( nWA, xWhere, xFullWhere, aTables, aParams, aRE, aRows )
    METHOD TryIndexJoinScan( nWA, xWhere, aTables, aParams, aRE, aRows, aJoins )
-   METHOD IndexInfo( nWA )
    METHOD BuildKeyExpr( nWA, cField )
-   METHOD CreateTempIndex( nWA, cField )
-   METHOD DropTempIndex( nWA, cTempFile )
    METHOD ExtractStrWidth( cExpr )
    METHOD TryCompoundSeek( nWA, xWhere, xFullWhere, aTables, aParams, aRE, aRows )
    METHOD ExtractEqPairs( xW, aTables, aParams, aOut )
@@ -344,95 +338,6 @@ METHOD FindCompoundTag( nWA, aFields ) CLASS TSqlIndex
 RETURN nBestTag
 
 
-/*
- * Apply scope boundaries for range queries.
- *
- * CDX advantage: Can switch to the best tag for this field from among
- *   multiple available tags, then set scope on that specific tag.
- *   After the query, the original tag order is restored.
- *
- * NTX limitation: ordScope() applies to the currently active index.
- *   FindBestTag must select the right .ntx file first. Only one
- *   scope can be active at a time across all attached NTX files.
- */
-METHOD ApplyScope( nWA, cField, xLow, xHigh ) CLASS TSqlIndex
-
-   LOCAL nSaved, nTag, cRDD
-   LOCAL xScopeLow, xScopeHigh, nPrevTag
-
-   nSaved := Select()
-   dbSelectArea( nWA )
-
-   cRDD := Upper( rddName() )
-
-   /* Save current tag so we can restore it after CDX tag switch */
-   nPrevTag := ordSetFocus()
-
-   nTag := ::FindBestTag( nWA, cField )
-   IF nTag == 0
-      /* No matching index — restore previous tag and fall back to full scan */
-      IF nPrevTag > 0
-         ordSetFocus( nPrevTag )
-      ENDIF
-      dbSelectArea( nSaved )
-      RETURN .F.
-   ENDIF
-
-   xScopeLow := ::BuildKey( nWA, xLow )
-   xScopeHigh := ::BuildKey( nWA, xHigh )
-
-   IF cRDD == "DBFCDX"
-      /* CDX: tag is already set by FindBestTag. ordScope applies to active tag.
-       * Multiple tags can have independent scopes in CDX. */
-      ordScope( 0, xScopeLow )
-      ordScope( 1, xScopeHigh )
-   ELSE
-      /* NTX: only one active index at a time. Scope applies globally. */
-      ordScope( 0, xScopeLow )
-      ordScope( 1, xScopeHigh )
-   ENDIF
-
-   dbSelectArea( nSaved )
-
-RETURN .T.
-
-
-METHOD ClearScope( nWA ) CLASS TSqlIndex
-
-   LOCAL nSaved
-
-   nSaved := Select()
-   dbSelectArea( nWA )
-
-   ordScope( 0, NIL )
-   ordScope( 1, NIL )
-
-   dbSelectArea( nSaved )
-
-RETURN NIL
-
-
-METHOD ApplySeek( nWA, cField, xValue ) CLASS TSqlIndex
-
-   LOCAL nSaved, nTag, xSeekKey, lFound
-
-   nSaved := Select()
-   dbSelectArea( nWA )
-
-   nTag := ::FindBestTag( nWA, cField )
-   IF nTag == 0
-      dbSelectArea( nSaved )
-      RETURN .F.
-   ENDIF
-
-   xSeekKey := ::BuildKey( nWA, xValue )
-   lFound := dbSeek( xSeekKey, .T. )
-
-   dbSelectArea( nSaved )
-
-RETURN lFound
-
-
 METHOD BuildKey( nWA, xValue ) CLASS TSqlIndex
 
    LOCAL cExpr, nSaved, nWidth
@@ -714,34 +619,6 @@ METHOD TryIndexJoinScan( nWA, xWhere, aTables, aParams, aRE, aRows, aJoins ) CLA
 RETURN .F.
 
 
-METHOD IndexInfo( nWA ) CLASS TSqlIndex
-
-   LOCAL aTags, i, cInfo
-
-   aTags := ::ListTags( nWA )
-
-   cInfo := "RDD: " + ::DetectRDD( nWA ) + ;
-            "  Orders: " + hb_ntos( Len( aTags ) ) + Chr(10)
-
-   FOR i := 1 TO Len( aTags )
-      cInfo += "  [" + hb_ntos( i ) + "] " + ;
-               PadR( aTags[ i ][ 1 ], 12 ) + ;
-               " Key: " + aTags[ i ][ 2 ]
-      IF ! Empty( aTags[ i ][ 3 ] )
-         cInfo += " FOR: " + aTags[ i ][ 3 ]
-      ENDIF
-      IF aTags[ i ][ 4 ]
-         cInfo += " UNIQUE"
-      ENDIF
-      IF aTags[ i ][ 5 ]
-         cInfo += " DESC"
-      ENDIF
-      cInfo += Chr(10)
-   NEXT
-
-RETURN cInfo
-
-
 METHOD BuildKeyExpr( nWA, cField ) CLASS TSqlIndex
 
    LOCAL nSaved, nFPos, cType, nLen
@@ -774,66 +651,6 @@ METHOD BuildKeyExpr( nWA, cField ) CLASS TSqlIndex
 RETURN cField
 
 
-METHOD CreateTempIndex( nWA, cField ) CLASS TSqlIndex
-
-   LOCAL nSaved, cTable, cTempFile, cExpr, cRDD
-   LOCAL lOk := .F.
-
-   nSaved := Select()
-   dbSelectArea( nWA )
-
-   cRDD := rddName()
-   cTable := Lower( AllTrim( Alias() ) )
-   cField := Upper( AllTrim( cField ) )
-
-   cExpr := ::BuildKeyExpr( nWA, cField )
-
-   IF Upper( cRDD ) == "DBFCDX"
-      cTempFile := "__tmp_" + cTable + ".cdx"
-      BEGIN SEQUENCE
-         ordCreate( cTempFile, "__TMP_" + cField, cExpr )
-         lOk := .T.
-      RECOVER
-      END SEQUENCE
-   ELSE
-      cTempFile := "__tmp_" + cTable + "_" + Lower( cField ) + ".ntx"
-      BEGIN SEQUENCE
-         dbCreateIndex( cTempFile, cExpr )
-         lOk := .T.
-      RECOVER
-      END SEQUENCE
-   ENDIF
-
-   dbSelectArea( nSaved )
-
-   IF lOk
-      RETURN cTempFile
-   ENDIF
-
-RETURN ""
-
-
-METHOD DropTempIndex( nWA, cTempFile ) CLASS TSqlIndex
-
-   LOCAL nSaved
-
-   IF Empty( cTempFile )
-      RETURN NIL
-   ENDIF
-
-   nSaved := Select()
-   dbSelectArea( nWA )
-
-   ordSetFocus( 0 )
-   dbClearIndex()
-
-   dbSelectArea( nSaved )
-
-   FErase( cTempFile )
-
-RETURN NIL
-
-
 METHOD ExtractStrWidth( cExpr ) CLASS TSqlIndex
 
    LOCAL nComma, nParen, cWidth

_FiveSql2/test/bench_parser.prg

@@ -1,82 +0,0 @@
-/*
- * bench_parser.prg — Parser performance benchmark
- * Compares TSqlParser (original) vs TSqlParser2 (Pratt)
- *
- * Copyright (c) 2025-2026 Charles KWON (Charles KWON OhJun)
- * All rights reserved.
- */
-
-#include "FiveSqlDef.ch"
-#include "hbclass.ch"
-
-#define ITERS  10000
-
-PROCEDURE Main()
-
-   LOCAL aSQL, i, j, t0, t1, oLex, aTokens, oP, h
-   LOCAL nT1, nT2, aAllTokens
-
-   aSQL := { ;
-      "SELECT name, salary FROM employees WHERE salary > 5000", ;
-      "SELECT e.name, o.product FROM employees e JOIN orders o ON e.id = o.emp_id WHERE o.amount > 100", ;
-      "SELECT dept, COUNT(*) AS cnt, AVG(salary) AS avg_sal FROM employees GROUP BY dept HAVING AVG(salary) > 5000 ORDER BY avg_sal DESC", ;
-      "SELECT name FROM employees WHERE id IN (SELECT emp_id FROM orders WHERE amount > 500)", ;
-      "SELECT name, salary, ROW_NUMBER() OVER (PARTITION BY dept ORDER BY salary DESC) AS rn FROM employees", ;
-      "SELECT name, CASE WHEN salary > 7000 THEN 'High' WHEN salary > 5000 THEN 'Mid' ELSE 'Low' END AS tier FROM employees WHERE dept = 'Engineering' OR (salary > 6000 AND mgr_id IS NOT NULL)", ;
-      "INSERT INTO employees (id, name, dept, salary) VALUES (99, 'Test', 'QA', 5000)", ;
-      "UPDATE employees SET salary = salary * 1.1 + 500 WHERE dept = 'Sales' AND salary BETWEEN 4000 AND 6000" ;
-   }
-
-   ? "================================================================"
-   ? "  Parser Benchmark: TSqlParser vs TSqlParser2 (Pratt)"
-   ? "  Queries: " + hb_ntos( Len( aSQL ) ) + "   Iterations: " + hb_ntos( ITERS )
-   ? "================================================================"
-   ?
-
-   /* Pre-tokenize all queries */
-   aAllTokens := {}
-   FOR i := 1 TO Len( aSQL )
-      oLex := TSqlLexer():New( aSQL[ i ] )
-      oLex:Tokenize()
-      AAdd( aAllTokens, oLex:GetTokens() )
-   NEXT
-
-   /* Benchmark TSqlParser (original) */
-   t0 := hb_MilliSeconds()
-   FOR j := 1 TO ITERS
-      FOR i := 1 TO Len( aSQL )
-         oP := TSqlParser():New( aAllTokens[ i ], {} )
-         h := oP:Parse()
-      NEXT
-   NEXT
-   t1 := hb_MilliSeconds()
-   nT1 := t1 - t0
-   ? "  TSqlParser  (original) : " + Str( nT1, 8 ) + " ms  (" + ;
-     Str( nT1 * 1000 / ( ITERS * Len( aSQL ) ), 6, 1 ) + " us/parse)"
-
-   /* Benchmark TSqlParser2 (Pratt) */
-   t0 := hb_MilliSeconds()
-   FOR j := 1 TO ITERS
-      FOR i := 1 TO Len( aSQL )
-         oP := TSqlParser2():New( aAllTokens[ i ], {} )
-         h := oP:Parse()
-      NEXT
-   NEXT
-   t1 := hb_MilliSeconds()
-   nT2 := t1 - t0
-   ? "  TSqlParser2 (Pratt)    : " + Str( nT2, 8 ) + " ms  (" + ;
-     Str( nT2 * 1000 / ( ITERS * Len( aSQL ) ), 6, 1 ) + " us/parse)"
-
-   ?
-   IF nT2 > 0 .AND. nT1 > 0
-      IF nT1 > nT2
-         ? "  Pratt is " + Str( nT1 / nT2, 5, 2 ) + "x faster"
-      ELSEIF nT2 > nT1
-         ? "  Original is " + Str( nT2 / nT1, 5, 2 ) + "x faster"
-      ELSE
-         ? "  Same speed"
-      ENDIF
-   ENDIF
-   ? "================================================================"
-
-RETURN

_FiveSql2/test/test_parser_cmp.prg

@@ -1,98 +0,0 @@
-/*
- * test_parser_cmp.prg — Compare AST output: TSqlParser vs TSqlParser2 (Pratt)
- *
- * Runs identical SQL through both parsers and verifies the AST hashes
- * are structurally identical.
- *
- * Copyright (c) 2025-2026 Charles KWON (Charles KWON OhJun)
- * All rights reserved.
- */
-
-#include "FiveSqlDef.ch"
-#include "hbclass.ch"
-
-STATIC s_nPass := 0
-STATIC s_nFail := 0
-
-PROCEDURE Main()
-
-   ? "================================================================"
-   ? "  TSqlParser vs TSqlParser2 (Pratt) — AST Comparison"
-   ? "================================================================"
-   ?
-
-   Cmp( "Simple SELECT",        "SELECT name, salary FROM employees WHERE salary > 5000" )
-   Cmp( "SELECT *",             "SELECT * FROM employees" )
-   Cmp( "JOIN",                 "SELECT e.name, o.product FROM employees e JOIN orders o ON e.id = o.emp_id" )
-   Cmp( "LEFT JOIN",            "SELECT e.name, o.product FROM employees e LEFT JOIN orders o ON e.id = o.emp_id" )
-   Cmp( "GROUP BY",             "SELECT dept, COUNT(*) AS cnt FROM employees GROUP BY dept" )
-   Cmp( "HAVING",               "SELECT dept, AVG(salary) AS avg_sal FROM employees GROUP BY dept HAVING AVG(salary) > 6000" )
-   Cmp( "ORDER BY DESC",        "SELECT name, salary FROM employees ORDER BY salary DESC, name ASC" )
-   Cmp( "DISTINCT + TOP",       "SELECT DISTINCT TOP 5 dept FROM employees" )
-   Cmp( "Subquery IN",          "SELECT name FROM employees WHERE id IN (SELECT emp_id FROM orders)" )
-   Cmp( "Subquery NOT IN",      "SELECT name FROM employees WHERE id NOT IN (1, 2, 3)" )
-   Cmp( "BETWEEN",              "SELECT name FROM employees WHERE salary BETWEEN 5000 AND 8000" )
-   Cmp( "NOT BETWEEN",          "SELECT name FROM employees WHERE salary NOT BETWEEN 1000 AND 2000" )
-   Cmp( "LIKE ESCAPE",          "SELECT name FROM products WHERE name LIKE '%10!%%' ESCAPE '!'" )
-   Cmp( "IS NULL",              "SELECT name FROM employees WHERE mgr_id IS NULL" )
-   Cmp( "IS NOT NULL",          "SELECT name FROM employees WHERE mgr_id IS NOT NULL" )
-   Cmp( "OR + AND",             "SELECT * FROM employees WHERE dept = 'Sales' OR (salary > 7000 AND mgr_id = 0)" )
-   Cmp( "NOT",                  "SELECT * FROM employees WHERE NOT (salary < 5000)" )
-   Cmp( "Arithmetic",           "SELECT name, salary * 12 + 1000 AS annual FROM employees" )
-   Cmp( "Unary minus",          "SELECT -salary FROM employees" )
-   Cmp( "String concat",        "SELECT name || ' - ' || dept FROM employees" )
-   Cmp( "CASE WHEN",            "SELECT name, CASE WHEN salary > 7000 THEN 'High' WHEN salary > 5000 THEN 'Mid' ELSE 'Low' END AS tier FROM employees" )
-   Cmp( "Nested function",      "SELECT UPPER(SUBSTR(name, 1, 3)) FROM employees" )
-   Cmp( "COUNT(*)",             "SELECT COUNT(*) FROM employees" )
-   Cmp( "Window ROW_NUMBER",    "SELECT name, ROW_NUMBER() OVER (ORDER BY salary DESC) AS rn FROM employees" )
-   Cmp( "Window PARTITION",     "SELECT name, RANK() OVER (PARTITION BY dept ORDER BY salary DESC) AS rnk FROM employees" )
-   Cmp( "UNION ALL",            "SELECT name FROM employees WHERE dept = 'Sales' UNION ALL SELECT name FROM employees WHERE dept = 'HR'" )
-   Cmp( "INSERT",               "INSERT INTO employees (id, name) VALUES (99, 'Test')" )
-   Cmp( "UPDATE",               "UPDATE employees SET salary = 9999 WHERE id = 1" )
-   Cmp( "DELETE",               "DELETE FROM employees WHERE id = 99" )
-   Cmp( "CTE simple",           "WITH top_e AS (SELECT name FROM employees WHERE salary > 7000) SELECT * FROM top_e" )
-
-   ?
-   ? "================================================================"
-   ? "  Pass: " + hb_ntos( s_nPass ) + "/" + hb_ntos( s_nPass + s_nFail )
-   IF s_nFail == 0
-      ? "  ALL AST OUTPUTS IDENTICAL"
-   ENDIF
-   ? "================================================================"
-
-RETURN
-
-
-STATIC FUNCTION Cmp( cLabel, cSQL )
-
-   LOCAL oLex, aTokens, oP1, oP2, h1, h2
-   LOCAL cAST1, cAST2
-
-   /* Tokenize once */
-   oLex := TSqlLexer():New( cSQL )
-   oLex:Tokenize()
-   aTokens := oLex:GetTokens()
-
-   /* Parse with TSqlParser (original) */
-   oP1 := TSqlParser():New( AClone( aTokens ), {} )
-   h1 := oP1:Parse()
-
-   /* Parse with TSqlParser2 (Pratt) */
-   oP2 := TSqlParser2():New( AClone( aTokens ), {} )
-   h2 := oP2:Parse()
-
-   /* Serialize both ASTs for comparison */
-   cAST1 := hb_ValToExp( h1 )
-   cAST2 := hb_ValToExp( h2 )
-
-   IF cAST1 == cAST2
-      s_nPass++
-      ? "  PASS: " + cLabel
-   ELSE
-      s_nFail++
-      ? "  FAIL: " + cLabel
-      ? "    P1: " + Left( cAST1, 120 )
-      ? "    P2: " + Left( cAST2, 120 )
-   ENDIF
-
-RETURN NIL

hbrt/class.go

@@ -298,7 +298,14 @@ func (t *Thread) tryBinaryOp(op int) bool {
 	if !a.IsObject() {
 		return false
 	}
-	cls := GetClass(a.AsArray().Class)
+	// AsArray can return nil if the ptr field is unset despite an object
+	// tag — a corrupted Value that would otherwise crash at `.Class`.
+	// Guard defensively; correct construction paths never hit this.
+	arr := a.AsArray()
+	if arr == nil {
+		return false
+	}
+	cls := GetClass(arr.Class)
 	if cls == nil || cls.Operators[op] == nil {
 		return false
 	}