flowgraph optimize_cfg Assertion for if-else-expression with if-else-expression as condition

[15r10nk]

Bug report

Bug description:

a if (1 if b else c) else d

output (Python 3.12.0rc3+):

python: Python/flowgraph.c:1598: optimize_cfg: Assertion `no_redundant_nops(g)' failed.

tested with the current 3.12 branch (538f505)

CPython versions tested on:

3.12

Operating systems tested on:

Linux

Linked PRs

• [3.12] gh-109889: comment out assertion indicating a failed optimization of a redundant NOP #109899
• gh-109889: fix compiler's redundant NOP detection to look past NOPs with no lineno when looking for the next instruction's lineno #109987
• [3.12] gh-109889: fix compiler's redundant NOP detection to look past NOPs with no lineno when looking for the next instruction's lineno (GH-109987) #110048

[AA-Turner]

cc: @iritkatriel

[iritkatriel]

The optimizer removes NOPs which are redundant (don't have important line number info attached). But there is a bug where it misses the case where there is a basic block that contains a single such NOP (and nothing else).

This is not a correctness issue, it's only an optimization failing. I will make a PR for 3.12 to just remove the assertion. In 3.13 I will fix this optimization.

[iritkatriel]

I will make a PR for 3.12 to just remove the assertion. In 3.13 I will fix this optimization.

I mean remove the assertion in 3.12.0. We can fix in 3.12.1.