Fix bug in cirq-ft due to which T-complexity fails for gates with an empty decomposition / no-op #6252
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…empty decomposition / no-op
fdmalone
approved these changes
Aug 17, 2023
NoureldinYosri
approved these changes
Aug 17, 2023
| def test_known_decomposition_empty_unitary(): | ||
| class DecomposeEmptyList(cirq.testing.SingleQubitGate): | ||
| def _decompose_(self, _): | ||
| return [] |
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check if it's pass as well. _decompose_ is usually a generator
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It does pass when _decompose_ is an empty generator - the test for cirq_ft.SelectSwapQROM exercises that path. Also, a decompose method with only pass will not be a generator, so we'll have to do something like if False: yield [], which would be awkward.
Codecov ReportPatch coverage:
Additional details and impacted files@@ Coverage Diff @@
## master #6252 +/- ##
==========================================
- Coverage 97.38% 97.38% -0.01%
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Files 1116 1116
Lines 96100 96110 +10
==========================================
+ Hits 93588 93593 +5
- Misses 2512 2517 +5
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This PR fixes two bugs in Cirq-FT
SelectSwapQROMis now hashablecirq_ft.t_complexity(gate)failed for some corner cases likecirq_ft.SwapWithZeroGate(0,4,1)**-1)because if a gate has an empty decomposition (i.e. it's a no-op) the_decompose_once_considering_known_decompositionmethod would return aNoneinstead of an empty list. The former implies we don't know the decomposition whereas the latter means the T-complexity is all 0.