Exception for Examples.Basics.BasicTests:f2 from sbv-4.4

Math

\[x \cdot x - y \cdot y\]

FPCore

(FPCore (x y) :precision binary64 (- (* x x) (* y y)))

C

double code(double x, double y) {
	return ((double) (((double) (x * x)) - ((double) (y * y))));
}

Reproduce

Please include this information when filing a bug report:

herbie shell --seed 2020203 
(FPCore (x y)
  :name "Examples.Basics.BasicTests:f2 from sbv-4.4"
  :precision binary64
  (- (* x x) (* y y)))

Backtrace

first: contract violation expected: (and/c list? (not/c empty?)) given: '()		L	C
batch-eval-progs	/data/pavpan/nightlies/herbie/cleanup/src/programs.rkt	107	0
batch-errors	/data/pavpan/nightlies/herbie/cleanup/src/points.rkt	169	0
atab-add-altns	/data/pavpan/nightlies/herbie/cleanup/src/core/alt-table.rkt	194	0
(unnamed)	/opt/racket-7.5/collects/racket/contract/private/arrow-val-first.rkt	486	18
finalize-iter!	/data/pavpan/nightlies/herbie/cleanup/src/mainloop.rkt	273	0
run-iter!	/data/pavpan/nightlies/herbie/cleanup/src/mainloop.rkt	341	0
for-loop	/data/pavpan/nightlies/herbie/cleanup/src/mainloop.rkt	379	4
run-improve41	/data/pavpan/nightlies/herbie/cleanup/src/mainloop.rkt	360	0
.../more-scheme.rkt:261:28	unknown
run	/opt/racket-7.5/share/pkgs/profile-lib/main.rkt	39	2
profile-thunk16	/opt/racket-7.5/share/pkgs/profile-lib/main.rkt	9	0
(unnamed)	/opt/racket-7.5/collects/racket/private/more-scheme.rkt	261	28

Reproduce

herbie shell --seed 2020203 
(FPCore (x y)
  :name "Examples.Basics.BasicTests:f2 from sbv-4.4"
  :precision binary64
  (- (* x x) (* y y)))