lanx@lanx-1005HA:~$ perl -Mre=debug -e' print "aaa" =~ /(a+){1}+a/ '
Compiling REx "(a+){1}+a"
Final program:
   1: CURLYX[0] {1,1} (11)
   3:   OPEN1 (5)
   5:     PLUS (8)
   6:       EXACT <a> (0)
   8:   CLOSE1 (10)
  10: WHILEM (0)
  11: NOTHING (12)
  12: EXACT <a> (14)
  14: END (0)
anchored "a" at 0 floating "aa" at 0..2147483647 (checking floating) plus minlen 2 
Matching REx "(a+){1}+a" against "aaa"
Intuit: trying to determine minimum start position...
  Found floating substr "aa" at offset 0...
  Found anchored substr "a" at offset 0...
  (multiline anchor test skipped)
Intuit: Successfully guessed: match at offset 0
   0 <> <aaa>                |  1:CURLYX[0] {1,1}(11)
   0 <> <aaa>                | 10:  WHILEM(0)
                                    whilem: matched 0 out of 1..1
   0 <> <aaa>                |  3:    OPEN1(5)
   0 <> <aaa>                |  5:    PLUS(8)
                                      EXACT <a> can match 3 times out of 2147483647...
   3 <aaa> <>                |  8:      CLOSE1(10)
   3 <aaa> <>                | 10:      WHILEM(0)
                                        whilem: matched 1 out of 1..1
   3 <aaa> <>                | 11:        NOTHING(12)
   3 <aaa> <>                | 12:        EXACT <a>(14)
                                          failed...
                                        failed...
   2 <aa> <a>                |  8:      CLOSE1(10)
   2 <aa> <a>                | 10:      WHILEM(0)
                                        whilem: matched 1 out of 1..1
   2 <aa> <a>                | 11:        NOTHING(12)
   2 <aa> <a>                | 12:        EXACT <a>(14)
   3 <aaa> <>                | 14:        END(0)
Match successful!
aaFreeing REx: "(a+){1}+a"