Fix partial matching bug in pcre2_dfa_match().

ChangeLog

@@ -79,6 +79,10 @@ existing "allusedtext" modifier and, as for complete matches, this facility is
 available only for non-JIT matching, because JIT does not maintain the first
 and last consulted characters.
 
+15. DFA matching (using pcre2_dfa_match()) was not recognising a partial match
+if the end of the subject was encountered in a lookahead (conditional or
+otherwise), an atomic group, or a recursion.
+
 
 Version 10.33 16-April-2019
 ---------------------------

src/pcre2_dfa_match.c

@@ -3152,8 +3152,8 @@ for (;;)
 
   /* We have finished the processing at the current subject character. If no
   new states have been set for the next character, we have found all the
-  matches that we are going to find. If we are at the top level and partial
+  matches that we are going to find. If partial matching has been requested,
-  matching has been requested, check for appropriate conditions.
+  check for appropriate conditions.
 
   The "forced_ fail" variable counts the number of (*F) encountered for the
   character. If it is equal to the original active_count (saved in
@@ -3165,8 +3165,7 @@ for (;;)
 
   if (new_count <= 0)
     {
-    if (rlevel == 1 &&                               /* Top level, and */
+    if (could_continue &&                            /* Some could go on, and */
-        could_continue &&                            /* Some could go on, and */
         forced_fail != workspace[1] &&               /* Not all forced fail & */
         (                                            /* either... */
         (mb->moptions & PCRE2_PARTIAL_HARD) != 0      /* Hard partial */
@@ -3175,8 +3174,8 @@ for (;;)
          match_count < 0)                            /* no matches */
         ) &&                                         /* And... */
         (
-        partial_newline ||                           /* Either partial NL */
+        partial_newline ||                     /* Either partial NL */
-          (                                          /* or ... */
+          (                                    /* or ... */
           ptr >= end_subject &&                /* End of subject and */
           ptr > mb->start_used_ptr)            /* Inspected non-empty string */
           )

testdata/testinput6

@@ -4972,4 +4972,26 @@
 \= Expect no match
     0
 
+/(?<=pqr)abc(?=xyz)/
+    123pqrabcxy\=ps,allusedtext
+    123pqrabcxyz\=ps,allusedtext
+
+/(?>a+b)/
+    aaaa\=ps
+    aaaab\=ps
+    
+/(abc)(?1)/
+    abca\=ps
+    abcabc\=ps
+
+/(?(?=abc).*|Z)/
+    ab\=ps
+    abcxyz\=ps
+
+/(abc)++x/
+    abcab\=ps
+    abc\=ps 
+    ab\=ps
+    abcx  
+
 # End of testinput6

testdata/testoutput6

@@ -7809,4 +7809,40 @@ No match
     0
 No match
 
+/(?<=pqr)abc(?=xyz)/
+    123pqrabcxy\=ps,allusedtext
+Partial match: pqrabcxy
+               <<<
+    123pqrabcxyz\=ps,allusedtext
+ 0: pqrabcxyz
+    <<<   >>>
+
+/(?>a+b)/
+    aaaa\=ps
+Partial match: aaaa
+    aaaab\=ps
+ 0: aaaab
+    
+/(abc)(?1)/
+    abca\=ps
+Partial match: abca
+    abcabc\=ps
+ 0: abcabc
+
+/(?(?=abc).*|Z)/
+    ab\=ps
+Partial match: ab
+    abcxyz\=ps
+ 0: abcxyz
+
+/(abc)++x/
+    abcab\=ps
+Partial match: abcab
+    abc\=ps 
+Partial match: abc
+    ab\=ps
+Partial match: ab
+    abcx  
+ 0: abcx
+
 # End of testinput6