I've started working on a patch for #7313 . So far I tried to replace C types in `src/libstd/unstable/*` and related files.
So far, I have two questions. Is there a convention for passing pointers around in `std` as Rust types? Sometimes pointers are passed around as `*c_char` (which seems to be an `*i8`), `*c_void` or `*u8`, which leads to a lot of casts. E.g: [`exchange_malloc`](https://github.com/fhahn/rust/compare/issue-7313-replace-c-types?expand=1#diff-39f44b8c3f4496abab854b3425ac1617R60) used to return a `*c_char` but the function in turn only calls `malloc_raw` which returns a `*c_void`.
Is there a specific reason for this?
The second question is about `CString` and related functions like `with_c_str`. At the moment these functions use `*c_char*`. Should I replace it with `*u8` or keep it, because it's an wrapper around classical C strings?
[On 2013-12-06, I wrote to the rust-dev mailing list](https://mail.mozilla.org/pipermail/rust-dev/2013-December/007263.html):
> Subject: Let’s avoid having both foo() and foo_opt()
>
> We have some functions and methods such as [std::str::from_utf8](http://static.rust-lang.org/doc/master/std/str/fn.from_utf8.html) that may succeed and give a result, or fail when the input is invalid.
>
> 1. Sometimes we assume the input is valid and don’t want to deal with the error case. Task failure works nicely.
>
> 2. Sometimes we do want to do something different on invalid input, so returning an `Option<T>` works best.
>
> And so we end up with both `from_utf8` and `from_utf8`. This particular case is worse because we also have `from_utf8_owned` and `from_utf8_owned_opt`, to cover everything.
>
> Multiplying names like this is just not good design. I’d like to reduce this pattern.
>
> Getting behavior 1. when you have 2. is easy: just call `.unwrap()` on the Option. I think we should rename every `foo_opt()` function or method to just `foo`, remove the old `foo()` behavior, and tell people (through documentation) to use `foo().unwrap()` if they want it back?
>
> The downsides are that unwrap is more verbose and gives less helpful error messages on task failure. But I think it’s worth it.
The email discussion has gone around long enough. Let’s discuss a concrete proposal. For the following functions or methods, I removed `foo` (that caused task failure) and renamed `foo_opt` (that returns `Option`) to just `foo`.
Vector methods:
* `get_opt` (rename only, `get` did not exist as it would have been just `[]`)
* `head_opt`
* `last_opt`
* `pop_opt`
* `shift_opt`
* `remove_opt`
`std::path::BytesContainer` method:
* `container_as_str_opt`
`std::str` functions:
* `from_utf8_opt`
* `from_utf8_owned_opt` (also remove the now unused `not_utf8` condition)
Is there something else that should recieve the same treatement?
I did not rename `recv_opt` on channels based on @brson’s [feedback](https://mail.mozilla.org/pipermail/rust-dev/2013-December/007270.html).
Feel free to pick only some of these commits.
To build for the cortex-M series ARM processors LLC needs to be told to build for the thumb instruction set. There are two ways to do this, either with the triple "thumb\*-\*-\*" or with -march=thumb (which just overrides the triple anyway). I chose the first way.
The following will fail because the local cc doesn't know what to do with -mthumb.
````
rustc test.rs --lib --target thumb-linux-eab
error: linking with `cc` failed: exit code: 1
note: cc: error: unrecognized command line option ‘-mthumb’
````
Changing the linker works as expected.
````
rustc test.rs --lib --target thumb-linux-eabi --linker arm-none-eabi-gcc
````
Ideally I'd have the triple thumb-none-eabi, but adding a new OS looks like much more work (and I'm not familiar enough with what it does to know if it is needed).
* Stop using hardcoded numbers that have to all get updated when something changes (inevitable errors and rebase conflicts) as well as removes some unneeded -Z options (obsoleted over time).
* Remove `std::rt::borrowck`
The included test case would essentially never finish compiling without this
patch. It recursies twice at every ExprParen meaning that the branching factor
is 2^n
The included test case will take so long to parse on the old compiler that it'll
surely never let this crop up again.
I wrote a chapter for the FFI tutorial that describes how to perform callbacks from C code to Rust and gives some hints about what to consider and synchronization.
I just needed that for my own wrapper and thought it would be helpful for others.
The included test case would essentially never finish compiling without this
patch. It recursies twice at every ExprParen meaning that the branching factor
is 2^n
The included test case will take so long to parse on the old compiler that it'll
surely never let this crop up again.
`Zero` and `One` have precise definitions in mathematics as the identities of the `Add` and `Mul` operations respectively. As such, types that implement these identities are now also required to implement their respective operator traits. This should reduce their misuse whilst still enabling them to be used in generalized algebraic structures (not just numbers). Existing usages of `#[deriving(Zero)]` in client code could break under these new rules, but this is probably a sign that they should have been using something like `#[deriving(Default)]` in the first place.
For more information regarding the mathematical definitions of the additive and multiplicative identities, see the following Wikipedia articles:
- http://wikipedia.org/wiki/Additive_identity
- http://wikipedia.org/wiki/Multiplicative_identity
Note that for floating point numbers the laws specified in the doc comments of `Zero::zero` and `One::one` may not always hold. This is true however for many other traits currently implemented by floating point numbers. What traits floating point numbers should and should not implement is an open question that is beyond the scope of this pull request.
The implementation of `std::num::pow` has been made more succinct and no longer requires `Clone`. The coverage of the associated unit test has also been increased to test for more combinations of bases, exponents, and expected results.
