editor: Fix underflow panic in block map sync when blocks overlap#51078
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editor: Fix underflow panic in block map sync when blocks overlap#51078
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In `BlockMap::sync`, blocks within an edited region are sorted and processed sequentially. Each block placement computes `rows_before_block` by subtracting `new_transforms.summary().input_rows` from the block's target position. The `Near`/`Below` cases have a guard that skips the block if the target is already behind the current progress, but `Above` and `Replace` were missing this guard. When a `Replace` block (tie_break 0) is processed before an `Above` block (tie_break 1) at the same or overlapping position, the `Replace` block consumes multiple input rows, advancing `input_rows` past the `Above` block's position. The subsequent `position - input_rows` subtraction underflows on `u32`, producing a huge `RowDelta` that wraps `wrap_row_end` past `wrap_row_start`, creating an inverted range that propagates through the display map layers and panics as `begin <= end (47 <= 0)` in a rope chunk slice. Add underflow guards to `Above` and `Replace`, matching the existing pattern in `Near`/`Below`.
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…1078) In `BlockMap::sync`, blocks within an edited region are sorted and processed sequentially. Each block placement computes `rows_before_block` by subtracting `new_transforms.summary().input_rows` from the block's target position. The `Near`/`Below` cases have a guard that skips the block if the target is already behind the current progress, but `Above` and `Replace` were missing this guard. When a `Replace` block (tie_break 0) is processed before an `Above` block (tie_break 1) at the same or overlapping position, the `Replace` block consumes multiple input rows, advancing `input_rows` past the `Above` block's position. The subsequent `position - input_rows` subtraction underflows on `u32`, producing a huge `RowDelta` that wraps `wrap_row_end` past `wrap_row_start`, creating an inverted range that propagates through the display map layers and panics as `begin <= end (47 <= 0)` in a rope chunk slice. Add underflow guards to `Above` and `Replace`, matching the existing pattern in `Near`/`Below`. Release Notes: - Fixed a source of underflowing subtractions causing spurious panics
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…1078) (cherry-pick to preview) (#51081) Cherry-pick of #51078 to preview ---- In `BlockMap::sync`, blocks within an edited region are sorted and processed sequentially. Each block placement computes `rows_before_block` by subtracting `new_transforms.summary().input_rows` from the block's target position. The `Near`/`Below` cases have a guard that skips the block if the target is already behind the current progress, but `Above` and `Replace` were missing this guard. When a `Replace` block (tie_break 0) is processed before an `Above` block (tie_break 1) at the same or overlapping position, the `Replace` block consumes multiple input rows, advancing `input_rows` past the `Above` block's position. The subsequent `position - input_rows` subtraction underflows on `u32`, producing a huge `RowDelta` that wraps `wrap_row_end` past `wrap_row_start`, creating an inverted range that propagates through the display map layers and panics as `begin <= end (47 <= 0)` in a rope chunk slice. Add underflow guards to `Above` and `Replace`, matching the existing pattern in `Near`/`Below`. Release Notes: - Fixed a source of underflowing subtractions causing spurious panics Co-authored-by: Lukas Wirth <[email protected]>
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In
BlockMap::sync, blocks within an edited region are sorted and processed sequentially. Each block placement computesrows_before_blockby subtractingnew_transforms.summary().input_rowsfrom the block's target position. TheNear/Belowcases have a guard that skips the block if the target is already behind the current progress, butAboveandReplacewere missing this guard.When a
Replaceblock (tie_break 0) is processed before anAboveblock (tie_break 1) at the same or overlapping position, theReplaceblock consumes multiple input rows, advancinginput_rowspast theAboveblock's position. The subsequentposition - input_rowssubtraction underflows onu32, producing a hugeRowDeltathat wrapswrap_row_endpastwrap_row_start, creating an inverted range that propagates through the display map layers and panics asbegin <= end (47 <= 0)in a rope chunk slice.Add underflow guards to
AboveandReplace, matching the existing pattern inNear/Below.Release Notes: