- (if headers
- `(%test-lowtag-and-headers
- ,value ,target ,not-p ,(car lowtags)
- ,function-p ',(canonicalize-headers headers)
- ,@other-args)
- `(%test-lowtag ,value ,target ,not-p ,(car lowtags)
- ,@other-args)))
+ (when headers
+ (error "can't test non-fixnum lowtags and headers at the same time"))
+ `(%test-lowtag ,value ,target ,not-p ,(car lowtags) ,@other-args))