Ignore {1} quantifiers.

ChangeLog

@@ -37,6 +37,9 @@ overflow. This bug was discovered by Karl Skomski with the LLVM fuzzer.
 9. The handling of callouts during the pre-pass for named group identification 
 has been tightened up.
 
+10. The quantifier {1} can be ignored, whether greedy, non-greedy, or 
+possessive. This is a very minor optimization.
+
 
 Version 10.20 30-June-2015
 --------------------------

src/pcre2_compile.c

@@ -4719,6 +4719,10 @@ for (;; ptr++)
       }
     else repeat_type = greedy_default;
 
+    /* If the repeat is {1} we can ignore it. */
+
+    if (repeat_max == 1 && repeat_min == 1) goto END_REPEAT;
+
     /* If previous was a recursion call, wrap it in atomic brackets so that
     previous becomes the atomic group. All recursions were so wrapped in the
     past, but it no longer happens for non-repeated recursions. In fact, the

testdata/testinput2

@@ -1259,7 +1259,11 @@
 
 /(a(b(?2)c)){0,2}/IB
 
-/[ab]{1}+/IB
+/[ab]{1}+/B
+
+/()(?1){1}/B
+
+/()(?1)/B
 
 /((w\/|-|with)*(free|immediate)*.*?shipping\s*[!.-]*)/Ii
      Baby Bjorn Active Carrier - With free SHIPPING!!

testdata/testoutput2

@@ -4533,16 +4533,33 @@ Capturing subpattern count = 2
 May match empty string
 Subject length lower bound = 0
 
-/[ab]{1}+/IB
+/[ab]{1}+/B
 ------------------------------------------------------------------
         Bra
-        [ab]{1,1}+
+        [ab]
+        Ket
+        End
+------------------------------------------------------------------
+
+/()(?1){1}/B
+------------------------------------------------------------------
+        Bra
+        CBra 1
+        Ket
+        Recurse
+        Ket
+        End
+------------------------------------------------------------------
+
+/()(?1)/B
+------------------------------------------------------------------
+        Bra
+        CBra 1
+        Ket
+        Recurse
         Ket
         End
 ------------------------------------------------------------------
-Capturing subpattern count = 0
-Starting code units: a b 
-Subject length lower bound = 1
 
 /((w\/|-|with)*(free|immediate)*.*?shipping\s*[!.-]*)/Ii
 Capturing subpattern count = 3