[std/re]fix terrible and strange interface

lib/impure/re.nim

@@ -142,7 +142,7 @@ proc matchOrFind(buf: cstring, pattern: Regex, matches: var openArray[string],
   return rawMatches[1] - rawMatches[0]
 
 proc findBounds*(buf: cstring, pattern: Regex, matches: var openArray[string],
-                 start = 0, bufSize: int): tuple[first, last: int] =
+                 start = 0, bufSize = 0): tuple[first, last: int] =
   ## returns the starting position and end position of `pattern` in `buf`
   ## (where `buf` has length `bufSize` and is not necessarily `'\0'` terminated),
   ## and the captured
@@ -200,7 +200,7 @@ proc findBounds*(s: string, pattern: Regex,
   result = findBounds(cstring(s), pattern, matches, start, s.len)
 
 proc findBounds*(buf: cstring, pattern: Regex,
-                 start = 0, bufSize: int): tuple[first, last: int] =
+                 start = 0, bufSize = 0): tuple[first, last: int] =
   ## returns the `first` and `last` position of `pattern` in `buf`,
   ## where `buf` has length `bufSize` (not necessarily `'\0'` terminated).
   ## If it does not match, `(-1,0)` is returned.
@@ -239,7 +239,7 @@ proc matchLen*(s: string, pattern: Regex, matches: var openArray[string],
   result = matchOrFind(cstring(s), pattern, matches, start.cint, s.len.cint, pcre.ANCHORED)
 
 proc matchLen*(buf: cstring, pattern: Regex, matches: var openArray[string],
-              start = 0, bufSize: int): int {.inline.} =
+              start = 0, bufSize = 0): int {.inline.} =
   ## the same as `match`, but it returns the length of the match,
   ## if there is no match, `-1` is returned. Note that a match length
   ## of zero can happen.
@@ -281,7 +281,7 @@ proc match*(s: string, pattern: Regex, matches: var openArray[string],
   result = matchLen(cstring(s), pattern, matches, start, s.len) != -1
 
 proc match*(buf: cstring, pattern: Regex, matches: var openArray[string],
-           start = 0, bufSize: int): bool {.inline.} =
+           start = 0, bufSize = 0): bool {.inline.} =
   ## returns `true` if `buf[start..<bufSize]` matches the `pattern` and
   ## the captured substrings in the array `matches`. If it does not
   ## match, nothing is written into `matches` and `false` is
@@ -315,7 +315,7 @@ proc find*(s: string, pattern: Regex, matches: var openArray[string],
   ## is written into `matches` and `-1` is returned.
   result = find(cstring(s), pattern, matches, start, s.len)
 
-proc find*(buf: cstring, pattern: Regex, start = 0, bufSize: int): int =
+proc find*(buf: cstring, pattern: Regex, start = 0, bufSize = 0): int =
   ## returns the starting position of `pattern` in `buf`,
   ## where `buf` has length `bufSize` (not necessarily `'\0'` terminated).
   ## If it does not match, `-1` is returned.
@@ -359,7 +359,7 @@ iterator findAll*(s: string, pattern: Regex, start = 0): string =
     yield substr(s, int(a), int(b)-1)
     i = b
 
-iterator findAll*(buf: cstring, pattern: Regex, start = 0, bufSize: int): string =
+iterator findAll*(buf: cstring, pattern: Regex, start = 0, bufSize = 0): string =
   ## Yields all matching `substrings` of `s` that match `pattern`.
   ##
   ## Note that since this is an iterator you should not modify the string you