In a token foo { <bar>+ }, the captures would not be stored. This was due to a bad interaction between :r and the cstack; the bstack contains the current cstack index we're at, but we don't grow the bstack when :r is on. We thus lost the count of captures, popping the entire cstack. This adds an extra bstack frame when :r is on to keep such counts, fixing the issue.

Author: jnthn

src/QAST/Compiler.nqp

@@ -289,6 +289,7 @@ class QAST::Compiler is HLL::Compiler {
         my $prefix    := self.unique('rxquant' ~ $backtrack);
         my $looplabel := self.post_new('Label', :result($prefix ~ '_loop'));
         my $donelabel := self.post_new('Label', :result($prefix ~ '_done'));
+        my $rcslabel  := self.post_new('Label', :result($prefix ~ '_ratchet_cstack'));
         my $min       := $node.min || 0;
         my $max       := $node.max // -1;
         my $needrep   := $min > 1 || $max > 1;
@@ -318,6 +319,8 @@ class QAST::Compiler is HLL::Compiler {
             $ops.push($donelabel);
         }
         else {
+            self.regex_mark($ops, $rcslabel, -1, 0) # to track cstack as we ratchet
+                if $backtrack eq 'r' && $max != 1;
             if $min == 0 { self.regex_mark($ops, $donelabel, %*REG<pos>, 0); }
             elsif $needmark { self.regex_mark($ops, $donelabel, -1, 0); }
             $ops.push($looplabel);
@@ -331,10 +334,16 @@ class QAST::Compiler is HLL::Compiler {
             }
             unless $max == 1 {
                 self.regex_mark($ops, $donelabel, %*REG<pos>, %*REG<rep>);
+                $ops.push_pirop('nqp_rxsetcaps', %*REG<bstack>, %*REG<cstack>)
+                    if $backtrack eq 'r';
                 $ops.push(self.regex_post($sep)) if $sep;
                 $ops.push_pirop('goto', $looplabel);
             }
             $ops.push($donelabel);
+            if $backtrack eq 'r' && $max != 1 {
+                self.regex_commit($ops, $rcslabel); # pop cstack/ratchet tracking mark
+                $ops.push($rcslabel);
+            }
             $ops.push_pirop('lt', %*REG<rep>, +$node.min, %*REG<fail>)
                 if $min > 1;
         }

src/ops/nqp.ops

@@ -1678,6 +1678,11 @@ Push a new backtracking mark onto $1 with label $2, position $3, and count $4
 
 Set $1 to be the index of latest mark frame $3 in stack $2.
 
+=item nqp_rxsetcaps(ptr, cstack)
+
+Sets the top cstack count in $1 to be the elements in $2, or 0 if it's null.
+Used to not lose count when doing ratcheting and replacing marks.
+
 =cut
 
 */
@@ -1705,6 +1710,12 @@ inline op nqp_rxpeek(out INT, in PMC, in LABEL) :base_core {
     $1 = ptr;
 }
 
+inline op nqp_rxsetcaps(in PMC, in PMC) :base_core {
+    PMC *bstack = $1;
+    VTABLE_set_integer_keyed_int(interp, bstack,
+        VTABLE_elements(interp, bstack) - 5,
+        PMC_IS_NULL($2) ? 0 : VTABLE_elements(interp, $2));
+}
 
 /*