several POSIX-compliance issues

[oguz-ismail]

• variable assignments where the value to be assigned is an empty string don't work, such as

  foo=
  

• redirections can't be applied to brace groups (and perhaps other compound commands):

  { :; } >&2
  

• the last case item in a case list has to be terminated explicitly, otherwise it won't work:

  case x in
  x) foo
  esac
  

• case items where the pattern is enclosed in a pair of parens don't work either:

  case x in
  (x) foo ;;
  esac
  

• pattern matching parameter expansions don't work at all:

  foo=bar
  echo ${foo#}
  

• when invoked with -c, the shell doesn't accept positional parameters:

  nsh -c '' nsh 1 2 3
  

I didn't test any further than this.

[nuta]

Nice catch! I enjoyed this list of bugs. Will fix it.