don't filter '\0' characters in string generation

compiler/rodutils.nim

@@ -22,7 +22,7 @@ proc toStrMaxPrecision*(f: BiggestFloat, literalPostfix = ""): string =
     else: result = "-INF"
   else:
     var buf: array[0..80, char]
-    let newLen = c_snprintf(buf.cstring, buf.len.uint, "%#.16e%s", f, literalPostfix.cstring)
+    discard c_snprintf(buf.cstring, buf.len.uint, "%#.16e%s", f, literalPostfix.cstring)
     result = $buf.cstring
 
 proc encodeStr*(s: string, result: var string) =

lib/system.nim

@@ -2427,12 +2427,7 @@ proc collectionToString[T](x: T, prefix, separator, suffix: string): string =
         result.add($value)
     # prevent temporary string allocation
     elif compiles(result.add(value)):
-      # don't insert '\0' characters into the result string
-      when value is char:
-        if value != '\0':
-          result.add(value)
-      else:
-        result.add(value)
+      result.add(value)
     else:
       result.add($value)
 

tests/system/toString.nim

@@ -46,6 +46,7 @@ doAssert dataStr == $data
 
 import strutils
 # array test
+
 let arr = ['H','e','l','l','o',' ','W','o','r','l','d','!','\0']
-doAssert $arr == "[H, e, l, l, o,  , W, o, r, l, d, !, ]"
+doAssert $arr == "[H, e, l, l, o,  , W, o, r, l, d, !, \0]"
 doAssert $arr.cstring == "Hello World!"