strange pattern replacing in parameter expansion

[Bernard VAUQUELIN]

Configuration Information [Automatically generated, do not change]:
Machine: i586
OS: linux-gnu
Compiler: i586-mandrake-linux-gnu-gcc
Compilation CFLAGS:  -DPROGRAM='bash' -DCONF_HOSTTYPE='i586' 
-DCONF_OSTYPE='linux-gnu' -DCONF_MACHTYPE='i586-mandrake-linux-gnu' 
-DCONF_VENDOR='mandrake' -DSHELL -DHAVE_CONFIG_H  -I.  -I. -I./include 
-I./lib -D_GNU_SOURCE  -O2 -fomit-frame-pointer -pipe -march=i586 
-mcpu=pentiumpro
uname output: Linux philtre.labri.fr 2.6.3-4mdk #1 Tue Mar 2 07:26:13 
CET 2004 i686 unknown unknown GNU/Linux
Machine Type: i586-mandrake-linux-gnu

Bash Version: 2.05b
Patch Level: 0
Release Status: release

Description:
       strange pattern replacing in parameter expansion

               x="*.c" ; echo $x ; echo ${x//.c/.o}
       gives
               toto.c titi.c
               *.o
       which seems strange to me,
       but
               x=`echo *.c` ; echo $x ; echo ${x//.c/.o}
       gives
               toto.c titi.c
               toto.o titi.o
       as expected