Treat empty-string-matching repeated conditionals the same as ordinary ones

when checking for an anchored pattern.

ChangeLog

@@ -179,6 +179,12 @@ subpattern was treated as anchored, when it should not have been, since the
 assumed empty second branch cannot be anchored. Demonstrated by test patterns 
 such as /(?(1)^())b/ or /(?(?=^))b/.
 
+40. A repeated conditional subpattern that could match an empty string was 
+always assumed to be unanchored. Now it it checked just like any other
+repeated conditional subpattern, and can be found to be anchored if the minimum 
+quantifier is one or more. I can't see much use for a repeated anchored
+pattern, but the behaviour is now consistent.
+
 
 Version 10.31 12-February-2018
 ------------------------------

src/pcre2_compile.c

@@ -7866,7 +7866,7 @@ do {
 
    /* Condition. If there is no second branch, it can't be anchored. */
 
-   else if (op == OP_COND)
+   else if (op == OP_COND || op == OP_SCOND)
      {
      if (scode[GET(scode,1)] != OP_ALT) return FALSE;
      if (!is_anchored(scode, bracket_map, cb, atomcount, inassert))

testdata/testinput2

@@ -5474,4 +5474,35 @@ a)"xI
 
 /(?(1)^())b/I
 
+/(?(1)^())+b/I,aftertext
+    abc
+
+/(?(1)^()|^)+b/I,aftertext
+    bbc 
+\= Expect no match     
+    abc
+
+/(?(1)^()|^)*b/I,aftertext
+    bbc 
+    abc
+    xbc 
+
+/(?(1)^())+b/I,aftertext
+    abc
+
+/(?(1)^a()|^a)+b/I,aftertext
+    abc 
+\= Expect no match     
+    bbc
+
+/(?(1)^|^(a))+b/I,aftertext
+    abc 
+\= Expect no match     
+    bbc
+
+/(?(1)^a()|^a)*b/I,aftertext
+    abc 
+    bbc
+    xbc 
+
 # End of testinput2

testdata/testoutput2

@@ -16671,6 +16671,98 @@ Max back reference = 1
 Last code unit = 'b'
 Subject length lower bound = 1
 
+/(?(1)^())+b/I,aftertext
+Capturing subpattern count = 1
+Max back reference = 1
+Last code unit = 'b'
+Subject length lower bound = 1
+    abc
+ 0: b
+ 0+ c
+
+/(?(1)^()|^)+b/I,aftertext
+Capturing subpattern count = 1
+Max back reference = 1
+Compile options: <none>
+Overall options: anchored
+First code unit = 'b'
+Subject length lower bound = 1
+    bbc 
+ 0: b
+ 0+ bc
+\= Expect no match     
+    abc
+No match
+
+/(?(1)^()|^)*b/I,aftertext
+Capturing subpattern count = 1
+Max back reference = 1
+First code unit = 'b'
+Subject length lower bound = 1
+    bbc 
+ 0: b
+ 0+ bc
+    abc
+ 0: b
+ 0+ c
+    xbc 
+ 0: b
+ 0+ c
+
+/(?(1)^())+b/I,aftertext
+Capturing subpattern count = 1
+Max back reference = 1
+Last code unit = 'b'
+Subject length lower bound = 1
+    abc
+ 0: b
+ 0+ c
+
+/(?(1)^a()|^a)+b/I,aftertext
+Capturing subpattern count = 1
+Max back reference = 1
+Compile options: <none>
+Overall options: anchored
+First code unit = 'a'
+Last code unit = 'b'
+Subject length lower bound = 2
+    abc 
+ 0: ab
+ 0+ c
+\= Expect no match     
+    bbc
+No match
+
+/(?(1)^|^(a))+b/I,aftertext
+Capturing subpattern count = 1
+Max back reference = 1
+Compile options: <none>
+Overall options: anchored
+Last code unit = 'b'
+Subject length lower bound = 1
+    abc 
+ 0: ab
+ 0+ c
+ 1: a
+\= Expect no match     
+    bbc
+No match
+
+/(?(1)^a()|^a)*b/I,aftertext
+Capturing subpattern count = 1
+Max back reference = 1
+Last code unit = 'b'
+Subject length lower bound = 1
+    abc 
+ 0: ab
+ 0+ c
+    bbc
+ 0: b
+ 0+ bc
+    xbc 
+ 0: b
+ 0+ c
+
 # End of testinput2
 Error -70: PCRE2_ERROR_BADDATA (unknown error number)
 Error -62: bad serialized data