Give error when case has an else branch even though all cases are already covered (#9930)

* Give error when case has an else branch even though all cases are already covered.
* Don't check for invalid else for type tyFloat..tyFloat128, tyString, tyError
* Remove unnecessary else in unittest.nim
* Fix sockets.nim

compiler/semstmts.nim

@@ -807,11 +807,13 @@ proc semCase(c: PContext, n: PNode; flags: TExprFlags): PNode =
       typ = commonType(typ, x.sons[1])
       closeScope(c)
     of nkElse:
-      chckCovered = false
       checkSonsLen(x, 1, c.config)
       x.sons[0] = semExprBranchScope(c, x.sons[0])
       typ = commonType(typ, x.sons[0])
       hasElse = true
+      if chckCovered and covered == toCover(c, n.sons[0].typ):
+        localError(c.config, x.info, "invalid else, all cases are already covered")
+      chckCovered = false
     else:
       illFormedAst(x, c.config)
   if chckCovered:

lib/deprecated/pure/sockets.nim

@@ -219,7 +219,6 @@ when defined(Posix):
     of AF_UNIX:        result = posix.AF_UNIX
     of AF_INET:        result = posix.AF_INET
     of AF_INET6:       result = posix.AF_INET6
-    else: discard
 
   proc toInt(typ: SockType): cint =
     case typ
@@ -227,7 +226,6 @@ when defined(Posix):
     of SOCK_DGRAM:     result = posix.SOCK_DGRAM
     of SOCK_SEQPACKET: result = posix.SOCK_SEQPACKET
     of SOCK_RAW:       result = posix.SOCK_RAW
-    else: discard
 
   proc toInt(p: Protocol): cint =
     case p
@@ -237,7 +235,6 @@ when defined(Posix):
     of IPPROTO_IPV6:   result = posix.IPPROTO_IPV6
     of IPPROTO_RAW:    result = posix.IPPROTO_RAW
     of IPPROTO_ICMP:   result = posix.IPPROTO_ICMP
-    else: discard
 
 else:
   proc toInt(domain: Domain): cint =
@@ -853,7 +850,6 @@ proc connect*(socket: Socket, address: string, port = Port(0),
       of AF_UNIX: s.sin_family = posix.AF_UNIX
       of AF_INET: s.sin_family = posix.AF_INET
       of AF_INET6: s.sin_family = posix.AF_INET6
-      else: nil
     if connect(socket.fd, cast[ptr TSockAddr](addr(s)), sizeof(s).cint) < 0'i32:
       OSError()
 

lib/pure/unittest.nim

@@ -239,7 +239,6 @@ method testEnded*(formatter: ConsoleOutputFormatter, testResult: TestResult) =
                     of OK: fgGreen
                     of FAILED: fgRed
                     of SKIPPED: fgYellow
-                    else: fgWhite
         styledEcho styleBright, color, prefix, "[", $testResult.status, "] ", resetStyle, testResult.testName
       else:
         rawPrint()