ADDED   ext/fts5/test/fts5leftjoin.test
Index: ext/fts5/test/fts5leftjoin.test
==================================================================
--- ext/fts5/test/fts5leftjoin.test
+++ ext/fts5/test/fts5leftjoin.test
@@ -0,0 +1,45 @@
+# 2014 June 17
+#
+# The author disclaims copyright to this source code.  In place of
+# a legal notice, here is a blessing:
+#
+#    May you do good and not evil.
+#    May you find forgiveness for yourself and forgive others.
+#    May you share freely, never taking more than you give.
+#
+#*************************************************************************
+# This file implements regression tests for SQLite library.  The
+# focus of this script is testing the FTS5 module.
+#
+
+source [file join [file dirname [info script]] fts5_common.tcl]
+set testprefix fts5leftjoin
+
+# If SQLITE_ENABLE_FTS5 is not defined, omit this file.
+ifcapable !fts5 {
+  finish_test
+  return
+}
+
+do_execsql_test 1.0 {
+  CREATE VIRTUAL TABLE vt USING fts5(x);
+  INSERT INTO vt VALUES('abc');
+  INSERT INTO vt VALUES('xyz');
+
+  CREATE TABLE t1(a INTEGER PRIMARY KEY);
+  INSERT INTO t1 VALUES(1), (2);
+}
+
+do_execsql_test 1.1 {
+  SELECT * FROM t1 LEFT JOIN (
+    SELECT rowid AS rrr, * FROM vt WHERE vt MATCH 'abc'
+  ) ON t1.a = rrr
+} {1 1 abc 2 {} {}}
+
+do_execsql_test 1.2 {
+  SELECT * FROM t1 LEFT JOIN vt ON (vt MATCH 'abc')
+} {1 abc 2 abc}
+
+finish_test
+
+

Index: src/whereexpr.c
==================================================================
--- src/whereexpr.c
+++ src/whereexpr.c
@@ -1176,10 +1176,13 @@
     prereqColumn = sqlite3WhereExprUsage(pMaskSet, pLeft);
     if( (prereqExpr & prereqColumn)==0 ){
       Expr *pNewExpr;
       pNewExpr = sqlite3PExpr(pParse, TK_MATCH, 
                               0, sqlite3ExprDup(db, pRight, 0));
+      if( ExprHasProperty(pExpr, EP_FromJoin) && pNewExpr ){
+        ExprSetProperty(pNewExpr, EP_FromJoin);
+      }
       idxNew = whereClauseInsert(pWC, pNewExpr, TERM_VIRTUAL|TERM_DYNAMIC);
       testcase( idxNew==0 );
       pNewTerm = &pWC->a[idxNew];
       pNewTerm->prereqRight = prereqExpr;
       pNewTerm->leftCursor = pLeft->iTable;

Index: test/fts3join.test
==================================================================
--- test/fts3join.test
+++ test/fts3join.test
@@ -58,7 +58,27 @@
 do_execsql_test 2.4 { SELECT * FROM ft3, ft2 WHERE y MATCH x; } {abc abc}
 
 do_catchsql_test 2.5 { 
   SELECT * FROM ft3, ft2 WHERE y MATCH x AND x MATCH y; 
 } {1 {unable to use function MATCH in the requested context}}
+
+do_execsql_test 3.0 {
+  CREATE VIRTUAL TABLE vt USING fts3(x);
+  INSERT INTO vt VALUES('abc');
+  INSERT INTO vt VALUES('xyz');
+
+  CREATE TABLE tt(a INTEGER PRIMARY KEY);
+  INSERT INTO tt VALUES(1), (2);
+}
+
+do_execsql_test 3.1 {
+  SELECT * FROM tt LEFT JOIN (
+    SELECT rowid AS rrr, * FROM vt WHERE vt MATCH 'abc'
+  ) ON tt.a = rrr
+} {1 1 abc 2 {} {}}
+
+do_execsql_test 3.2 {
+  SELECT * FROM tt LEFT JOIN vt ON (vt MATCH 'abc')
+} {1 abc 2 abc}
+
 
 finish_test