My goal is to explain the underlying concepts first (destructors and then ownership) with plenty of step-by-step examples, so that thoroughly explaining the semantics of mutability, boxes, moves, etc. is a breeze. I'm trying to avoid the comparisons with C++ that were done before, because this should be approachable for people coming from any language. C++ programmers already know these concepts so they aren't the audience that needs to be catered to. Comparisons with other languages can be done in separate documents (like [this one](https://github.com/mozilla/rust/wiki/Rust-for-CXX-programmers)).
This still needs examples for ownership (inherited mutability), owned boxes and managed boxes.
So this is a partial fix for #3469. Partial because it only works for simple constant expressions like `32/2` and `2+2` and not for any actual constants.
For example:
```
const FOO: uint = 2+2;
let v: [int * FOO];
```
results in:
```
error: expected constant expr for vector length: Non-constant path in constant expr
```
This seems to be because at the point of error (`typeck::astconv`) the def_map doesn't contain the constant and thus it can't lookup the actual expression (`2+2` in this case).
So, feedback on what I have so far and suggestions for how to address the constant issue?
All current meta items types (word, name-value, list) are now
properly parsed by rustc --cfg command line. Fixes#2399
Signed-off-by: Luca Bruno <lucab@debian.org>
librustc: Make the compiler ignore purity. …
For bootstrapping purposes, this commit does not remove all uses of
the keyword "pure" -- doing so would cause the compiler to no longer
bootstrap due to some syntax extensions ("deriving" in particular).
Instead, it makes the compiler ignore "pure". Post-snapshot, we can
remove "pure" from the language.
There are quite a few (~100) borrow check errors that were essentially
all the result of mutable fields or partial borrows of `@mut`. Per
discussions with Niko I think we want to allow partial borrows of
`@mut` but detect obvious footguns. We should also improve the error
message when `@mut` is erroneously reborrowed.
r? @nikomatsakis
For bootstrapping purposes, this commit does not remove all uses of
the keyword "pure" -- doing so would cause the compiler to no longer
bootstrap due to some syntax extensions ("deriving" in particular).
Instead, it makes the compiler ignore "pure". Post-snapshot, we can
remove "pure" from the language.
There are quite a few (~100) borrow check errors that were essentially
all the result of mutable fields or partial borrows of `@mut`. Per
discussions with Niko I think we want to allow partial borrows of
`@mut` but detect obvious footguns. We should also improve the error
message when `@mut` is erroneously reborrowed.
For bootstrapping purposes, this commit does not remove all uses of
the keyword "pure" -- doing so would cause the compiler to no longer
bootstrap due to some syntax extensions ("deriving" in particular).
Instead, it makes the compiler ignore "pure". Post-snapshot, we can
remove "pure" from the language.
There are quite a few (~100) borrow check errors that were essentially
all the result of mutable fields or partial borrows of `@mut`. Per
discussions with Niko I think we want to allow partial borrows of
`@mut` but detect obvious footguns. We should also improve the error
message when `@mut` is erroneously reborrowed.
Continuation of #5317. Actually use operands properly now, including any number of output operands.
Which means you can do things like call printf:
```Rust
fn main() {
unsafe {
do str::as_c_str(~"The answer is %d.\n") |c| {
let a = 42;
asm!("mov $0, %rdi\n\t\
mov $1, %rsi\n\t\
xorl %eax, %eax\n\t\
call _printf"
:
: "r"(c), "r"(a)
: "rdi", "rsi", "eax"
: "volatile","alignstack"
);
}
}
}
```
```
% rustc foo.rs
% ./foo
The answer is 42.
```
Or just add 2 numbers:
```Rust
fn add(a: int, b: int) -> int {
let mut c = 0;
unsafe {
asm!("add $2, $0"
: "=r"(c)
: "0"(a), "r"(b)
);
}
c
}
fn main() {
io::println(fmt!("%d", add(1, 2)));
}
```
```
% rustc foo.rs
% ./foo
3
```
Multiple outputs!
```Rust
fn addsub(a: int, b: int) -> (int, int) {
let mut c = 0;
let mut d = 0;
unsafe {
asm!("add $4, $0\n\t\
sub $4, $1"
: "=r"(c), "=r"(d)
: "0"(a), "1"(a), "r"(b)
);
}
(c, d)
}
fn main() {
io::println(fmt!("%?", addsub(5, 1)));
}
```
```
% rustc foo.rs
% ./foo
(6, 4)
```
This also classifies inline asm as RvalueStmtExpr instead of the somewhat arbitrary kind I made it initially. There are a few XXX's regarding what to do in the liveness and move passes.
r?
I want to use this function as a method. There's probably a better way to design this but the existing `ToBytes` trait is not what I am looking for (it has a parameter to indicate the byte order).
