Make scan support n_steps = 0 and empty input sequences

dee152ce · Rémi Louf · Brandon T. Willard · f63d372d · dee152ce · dee152ce
--- a/aesara/scan/basic.py
+++ b/aesara/scan/basic.py
@@ -888,6 +888,7 @@ def scan(
                n_shared_outs += 1
    n_sit_sot = len(sit_sot_inner_inputs)
    # Step 5.4 Outputs with no taps used in the input
    n_nit_sot = 0
    nit_sot_inner_outputs = []

--- a/aesara/scan/c_code/scan_perform.c
+++ b/aesara/scan/c_code/scan_perform.c
--- a/aesara/scan/op.py
+++ b/aesara/scan/op.py
--- a/aesara/scan/scan_perform.pyx
+++ b/aesara/scan/scan_perform.pyx
--- a/aesara/scan/scan_perform_ext.py
+++ b/aesara/scan/scan_perform_ext.py
--- a/tests/scan/test_basic.py
+++ b/tests/scan/test_basic.py