make tests green again; closes #5861

tests/async/tnewasyncudp.nim

@@ -62,7 +62,7 @@ proc launchSwarm(name: ptr SockAddr) {.async.} =
                                     16384, cast[ptr SockAddr](addr saddr),
                                     addr slen)
       size = 0
-      var grammString = $buffer.cstring
+      var grammString = $cstring(addr buffer)
       if grammString == message:
         saveSendingPort(sockport)
         inc(recvCount)
@@ -84,7 +84,7 @@ proc readMessages(server: AsyncFD) {.async.} =
                                   16384, cast[ptr SockAddr](addr(saddr)),
                                   addr(slen))
     size = 0
-    var grammString = $buffer.cstring
+    var grammString = $cstring(addr buffer)
     if grammString.startswith("Message ") and
        saddr.sin_addr.s_addr == 0x100007F:
       await sendTo(server, addr grammString[0], len(grammString),

tests/float/tfloat4.nim

@@ -9,7 +9,7 @@ proc c_sprintf(buf, fmt: cstring) {.importc:"sprintf", header: "<stdio.h>", vara
 
 proc floatToStr(f: float64): string =
   var buffer: array[128, char]
-  c_sprintf(buffer, "%.16e", f)
+  c_sprintf(addr buffer, "%.16e", f)
   result = ""
   for ch in buffer:
     if ch == '\0':

tests/system/toString.nim

@@ -50,4 +50,4 @@ import strutils
 
 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, !, \0]"
-doAssert $arr.cstring == "Hello World!"
+doAssert $cstring(unsafeAddr arr) == "Hello World!"