Early return if span is from expansion so we dont get empty span and ice later on

[Kivooeo]

Fixes #147255

The problem original was from that stmt.span was from expansion and it span was bigger than right part which is block.span, so it causes empty span and panic later on, I decided to add checks for both of them to be on the safe side

r? @fmease (you were in discussion on this issue so I decided to assign you, feel free to reroll)

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[chenyukang]

these errors are recurring, how can we implement a long-term fix.
i remember we had a try, but it was blocked by performance regression.

[Kivooeo]

This should not affect performance. As for a long-term fix, I’m not sure we can implement one, since it may occur in unexpected places. We can probably fix issues like this only gradually over time

[Kivooeo]

For example this ICE was since 1.86, which is pretty old, but I have no idea what has changed after 1.85 that could break this

[chenyukang]

This should not affect performance. As for a long-term fix, I’m not sure we can implement one, since it may occur in unexpected places. We can probably fix issues like this only gradually over time

i'm referring this one which have perf regression: #109082

i have a revisit on that PR, seems it was fixing a different issue (but general in similar kind).