Weird shopt behavior

[pjump]

Configuration Information [Automatically generated, do not change]:
Machine: x86_64
OS: linux-gnu
Compiler: gcc
Compilation CFLAGS:  -DPROGRAM='bash' -DCONF_HOSTTYPE='x86_64' 
-DCONF_OSTYPE='linux-gnu' -DCONF_MACHTYPE='x86_64-pc-linux-gnu' 
-DCONF_VENDOR='pc' -DLOCALEDIR='/usr/share/locale' -DPACKAGE='bash' -DSHELL 
-DHAVE_CONFIG_H   -I.  -I../. -I.././include -I.././lib  -D_FORTIFY_SOURCE=2 -g 
-O2 -fstack-protector --param=ssp-buffer-size=4 -Wformat 
-Werror=format-security -Wall
uname output: Linux laptop 3.19.0-32-generic #37~14.04.1-Ubuntu SMP Thu Oct 22 
09:41:40 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux
Machine Type: x86_64-pc-linux-gnu

Bash Version: 4.3
Patch Level: 11
Release Status: release

Description:
  Not sure if this is a bug (it does bug me a little), however:

  main(){
    shopt -s extglob
    local line='     x bar'
    echo "${line##*( )}"
    case "$line" in
      *( )x*) ;;
      *) ;;
    esac
  }

   fails with a syntax error on the first parenthesis in the case statement. It 
does turn extglob on
  in other contexts (the echo line), but the extglob in the case statement 
fails.
Interestingly, moving `shopt -s extglob` outside of main fixes the problem.

Fix:
        [Description of how to fix the problem.  If you don't know a
        fix for the problem, don't include this section.]