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Requirements on the target platform C implementation #46

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36fd33e
requirements on the platform C implementation
gnzlbg Nov 11, 2018
7fc7f85
add representation of bool true/false
gnzlbg Nov 11, 2018
df2e236
amend float unresolved question
gnzlbg Nov 11, 2018
8e009a1
fix typo: _Bool instead of Bool_
gnzlbg Nov 11, 2018
07f7021
remove non-dereferenceable pointer requirement
gnzlbg Nov 11, 2018
aadac80
differentiate platforms w/o NULL
gnzlbg Nov 12, 2018
2e0d82f
clean up unresolved questions
gnzlbg Nov 12, 2018
fcfb9c8
cleanup requirements
gnzlbg Nov 12, 2018
612f003
add unresolved questions about targets without conforming C implement…
gnzlbg Nov 12, 2018
f89431d
assume that the platform has a C implementation
gnzlbg Nov 12, 2018
25097ac
clarify the behavior if the C implementation does not satisfy our req…
gnzlbg Nov 12, 2018
36d3fb3
reword this all
gnzlbg Nov 12, 2018
c508026
typos
gnzlbg Nov 12, 2018
e9dbb11
fix section name in summary
gnzlbg Nov 12, 2018
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add unresolved questions about targets without conforming C implement… 
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gnzlbg committed Nov 12, 2018
commit 612f003549887a4d8b005638b0889a7d00bb4afd
8 changes: 8 additions & 0 deletions reference/src/representation/c_abi.md
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Expand Up @@ -71,4 +71,12 @@ are opened:
does not convey any information about the exact representation of its
niche, that is, it is different from `NonZero`.
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The documentation for NonNull says "*mut T but non-zero and covariant" (emphasis mine). Later on the documentation says "non-null"; i.e."non-zero" and "non-null" are used interchangeably.

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The docs might need fixing.

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The docs might need fixing.

I agree. However, somebody may have already read the documentation and made the assumption that NULL == 0 based on them, and may then be relying on that, so it should be announced loudly if that change is made. If it isn't too late, it would be good to do it at the same time Rust 2018 edition ships and maybe consider it part of Rust 2018.

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It is unclear at this point what we are going to require about the niches of &T, that probably will be part of the discussions about "validity", which are not taking place yet (hence why this is an unresolved question).


* **targets "without C"**:

* What should we do about targets whose C implementation is not standard
conforming? Do we require full standard conformance? Or only conformance of
some specific aspects that are required for FFI ?

* What should we do about targets that do not have a C implementation at all?

[latest_c_std]: http://www.open-std.org/jtc1/sc22/wg14/www/abq/c17_updated_proposed_fdis.pdf