为什么BASH_REMATCH不能用于引用的正则表达式？

The code is like this:

代码是这样的：

#!/bin/bash
if [[ foobarbletch =~ 'foo(bar)bl(.*)' ]]
 then
     echo "The regex matches!"
     echo $BASH_REMATCH
     echo ${BASH_REMATCH[1]}
     echo ${BASH_REMATCH[2]}
 fi
#!/bin/bash