Fix memlet propagation out of nested SDFGs#1176
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tbennun
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ThrudPrimrose
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validate_state's dimensionality-mismatch check dereferenced sdfg.arrays[src_node.data].veclen / sdfg.arrays[dst_node.data].veclen on every edge with other_subset set, assuming both endpoints were AccessNodes. Any edge whose src/dst is a NestedSDFG / MapEntry / MapExit / ConsumeEntry / ConsumeExit raised "AttributeError: 'NestedSDFG' object has no attribute 'data'" because scope nodes do not expose .data -- they route data via connectors, and any per-side packing lives on the inner descriptor. The crash blocked a 2nd/3rd canonicalize() call on the guarded imperfect-nest repro (a top-level guard above an outer map with a nested map and an extra-statement tail): the multi-pass pipeline eventually produces a deeper NSDFG whose inner NSDFG -> MapExit edge carries both src_subset and dst_subset, and validation aborts before the pipeline can reach a fixed point. Fix: read each side's veclen only when its endpoint is an AccessNode; default to 1 for scope nodes. The two View-exception branches had the same latent assumption -- guarded them with the same isinstance check. Closes the canonicalize idempotence crash: with this guard the repro reaches a stable fixed point (1x->(1,2), 2x=3x=4x=(2,2)) with no warnings, and the original "_it_X leaks into outer subsets" path is unaffected (those forms were the intentional WCR running-union encoding from PR #1176 -- the iterator IS in scope on the inner-out edge, so the SDFG is well-formed; the only thing missing was a validator that survives non-AccessNode endpoints). CORE_BUGFIXES.md: mark #3 (preserve_minima fabrication) as NOT-A-BUG (intentional WCR semantics); mark #4 (canonicalize idempotence) as RESOLVED by this fix; add #9 describing the validation guard with the sweep verification. Sweep: tests/transformations + tests/canonicalize + propagation + tests/passes -- 2074 passed, 25 failed (all pre-existing: 5 offset_loop_and_maps TODO-raise, 1 perf_loop_nesting refusal, 1 branch_elimination test-bug, plus environmental cache/import errors). One fewer failure than baseline (the canonicalize idem path now survives validation). Zero net regressions.
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Closes #1174.