Remove cyclic-definition handling from Clifford.from_circuit#10441
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jakelishman merged 3 commits intoJul 18, 2023
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This reliance on `RecursionError` could lead to CPython crashing, when the user had raised the recursion limit beyond what their operating system could actually support in terms of Python frames. This was particularly an issue with Windows when in a context that `jedi` is active (such as in an IPython session, or if `seaborn` was imported), since `jedi` unilaterally sets the recursion limit to 3000, while CPython tends to overflow the stack on Windows at around 2700 frames. Recursive `definition` fields are not valid data in the Qiskit model, as the definition is supposed to be hierarchical, and a decomposition in terms of gates that do not involve the current one in any form. For defining equivalences that may involve cycles, one should use the `EquivalenceLibrary` objects that Terra manages, and the transpiler takes advantage of via the `BasisTranslator`.
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itoko
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LGTM. The removal of test_from_gate_with_cyclic_definition makes sense to me now. (I didn't understand recursion definition fields are invalid in Qiskit model when I wrote it.)
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Summary
This reliance on
RecursionErrorcould lead to CPython crashing, when the user had raised the recursion limit beyond what their operating system could actually support in terms of Python frames. This was particularly an issue with Windows when in a context thatjediis active (such as in an IPython session, or ifseabornwas imported), sincejediunilaterally sets the recursion limit to 3000, while CPython tends to overflow the stack on Windows at around 2700 frames.Recursive
definitionfields are not valid data in the Qiskit model, as the definition is supposed to be hierarchical, and a decomposition in terms of gates that do not involve the current one in any form. For defining equivalences that may involve cycles, one should use theEquivalenceLibraryobjects that Terra manages, and the transpiler takes advantage of via theBasisTranslator.Details and comments
Close #10415. @itoko, you might want to look at this, since I don't know if you had a use-case in mind for the original recursion handling.
This should fix the CI problems that #8967 and #10208 have encountered.