It is a Bug
Color functions have an issue with respect to this that has been submitted.
Workaround
Don't try to do both calls in one string. Set the variable value to your inner variables. Then when you use them, use the @@
syntax directly. Like this:
@red-1:#ff0000;
@red-2:#990000;
@blue-1:#000ff;
@blue-2:#00099;
.setTheme(@theme){
@color-1:~"@{theme}-1";
@color-2:~"@{theme}-2";
@color-2faded: fade(@@color-2, 10%);
body.@{theme} .button{
background:@@color-1;
color:@color-2faded;
}
}
.setTheme(~"red");
Or without the extra variable:
.setTheme(@theme){
@color-1:~"@{theme}-1";
@color-2:~"@{theme}-2";
body.@{theme} .button{
background:@@color-1;
color: fade(@@color-2, 10%);
}
}