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[expr.add] Pointer subtraction when P-Q is out of range of ptrdiff_t is unclear #6268

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vasama opened this issue Jun 6, 2023 · 1 comment · Fixed by #6269
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[expr.add] Pointer subtraction when P-Q is out of range of ptrdiff_t is unclear #6268

vasama opened this issue Jun 6, 2023 · 1 comment · Fixed by #6269

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@vasama
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vasama commented Jun 6, 2023 •
edited

Otherwise, if P and Q point to, respectively, array elements i and j of the same array object x, the expression P - Q has the value i - j.

When i - j is not in range of ptrdiff_t, this seems to be undefined behaviour due to [expr.pre]. The note on 5.3 should probably be moved here, and a reference to [expr.pre] added.
@jensmaurer
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Sounds good. Care to submit a pull request?

@vasama vasama mentioned this issue Jun 7, 2023
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[expr.add] Clarify note on pointer subtraction vasama/cplusplus-draft
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@vasama @jensmaurer