LWG Poll 24: P1739R4 Avoid template bloat for safe_ranges in combination with "sub… #3777
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| If \tcode{decltype((F))} does not model | ||
| \tcode{\libconcept{convertible_to}<D>}, | ||
| \tcode{views::take(E, F)} is ill-formed. |
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"model" + ill-formed don't work together; advised LWG in http://lists.isocpp.org/lib/2020/02/15451.php
| If \tcode{decltype((F))} does not model | ||
| \tcode{\libconcept{convertible_to}<D>}, | ||
| \tcode{views::drop(E, F)} is ill-formed. |
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"model" + ill-formed don't work together; advised LWG in http://lists.isocpp.org/lib/2020/02/15451.php
| If \tcode{decltype((F))} does not model | ||
| \tcode{\libconcept{convertible_to}<D>}, | ||
| \tcode{views::counted(E, F)} is ill-formed. |
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"model" + ill-formed don't work together; advised LWG in http://lists.isocpp.org/lib/2020/02/15451.php
source/ranges.tex
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| then \tcode{((void) F, \placeholdernc{decay-copy}(E))}; | ||
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| otherwise, if \tcode{T} models |
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another "models"; see http://lists.isocpp.org/lib/2020/02/15452.php
(similarly for the other occurrences below)
This seems to make the entire paper unimplementable, and it thus should be rejected.
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@zygoloid , this paper incorrectly uses "models" pervasively, which makes it essentially unimplementable. I've emailed LWG, but I'm not sure if anything here can be resurrected editorially. |
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P2101R0 (applied with LWG poll 10) adds "If the validity or meaning of a program depends on whether a sequence of template arguments models a concept, and the concept is satisfied but not modeled, the program is ill-formed, no diagnostic required." |
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…range-y" view adaptors Also fixes NB DE 288 and US 272 (C++20 CD). [range.counted] Moved note to work with new wording.
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I encountered this when editing in a different paper. I find the current approach quite problematic from a comprehensibility standpoint, and I said this in person at Prague too, but it's too late in the cycle to fix this for C++20 (would require someone going through all the library wording and fixing all the places that say "models" when they mean to apply a machine-checkable set of requirements). |
…range-y" view adaptors
Also fixes NB DE 288 and US 272 (C++20 CD).
[range.counted] Moved note to work with new wording.
Fixes #3726.
Fixes cplusplus/papers#503.
Fixes cplusplus/nbballot#284.
Fixes cplusplus/nbballot#268.
Notes: