P2642: Avoid division by zero
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Description
Para 12.3 of the converting constructor from layout_stride::mapping explicitly divides by zero if the leftmost resp. rightmost extent is zero.
This a general issue with other constructors as well, e.g., if padding_value is zero.
The two-parameter constructor mapping(ext, pad) has a precondition that extents_type::index-cast(pad) is greater than zero. Thus, we already check in some cases. We should consider extending these checks to all the cases, so the mappings behave reasonably.
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Research direction
Start with paragraph 12.3 on the converting constructor from layout_stride::mapping, then compare the other mapping constructors, including mapping(ext, pad) and its existing precondition. Done means the constructors handle zero extents or padding without division by zero and apply consistent validity checks; no files or tests are named in the issue.
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Assessment
- Tech stack
- cpp
- Domain
- compilers
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 35/100