By carefully distinguishing falling back to the default arm from moving
on to the next pattern, this patch adjusts the codegen logic for range
and guarded arms of pattern matching expression. It is a more
appropriate way of fixing #12582 and #13027 without causing regressions
such as #13867.
Closes#13867
Turning a `&T` into an `&mut T` is undefined behaviour, and needs to be
done very very carefully. Providing a convenience function for exactly
this task is a bad idea, just tempting people into doing the wrong
thing.
(The right thing is to use types like `Cell`, `RefCell` or `Unsafe`.)
cc https://github.com/mozilla/rust/issues/13933
The logging macros now create a LogRecord, and pass that to the Logger. This will allow custom loggers to change the formatting, and possible filter on more properties of the log record.
DefaultLogger's formatting was taken from Python's default formatting:
`LEVEL:from: message`
Also included: fmt::Arguments now implement Show, so they can be used to
extend format strings.
@alexcrichton r?
The logging macros now create a LogRecord, and pass that to the
Logger, instead of passing a `level` and `args`. The new signature is:
trait Logger {
fn log(&mut self, record: &LogRecord);
}
The LogRecord includes additional values that may be useful to custom
loggers, and also allows for further expansion if not values are found
useful.
DefaultLogger's formatting was taken from Python's default formatting:
`LEVEL:from: message`
Also included: fmt::Arguments now implement Show, so they can be used to
extend format strings.
[breaking-change]
This patch fixes issue #13186.
When generating constant expression for enum, it is possible that
alignment of expression may be not equal to alignment of type. In that
case space after last struct field must be padded to match size of value
and size of struct. This commit adds that padding.
See detailed explanation in src/test/run-pass/trans-tag-static-padding.rs
This was removed because these could alias with `&const T` or `@mut T`
and those are now gone from the language. There are still aliasing
issues within local scopes, but this is correct for function parameters.
This also removes the no-op `noalias` marker on proc (not a pointer) and
leaves out the mention of #6750 because real type-based alias analysis
is not within the scope of best effort usage of the `noalias` attribute.
Test case:
pub fn foo(x: &mut &mut u32) {
**x = 5;
**x = 5;
}
Before:
define void @_ZN3foo20h0ce94c9671b0150bdaa4v0.0E(i32** nocapture readonly) unnamed_addr #0 {
entry-block:
%1 = load i32** %0, align 8
store i32 5, i32* %1, align 4
%2 = load i32** %0, align 8
store i32 5, i32* %2, align 4
ret void
}
After:
define void @_ZN3foo20h0ce94c9671b0150bdaa4v0.0E(i32** noalias nocapture readonly) unnamed_addr #0 {
entry-block:
%1 = load i32** %0, align 8
store i32 5, i32* %1, align 4
ret void
}
Closes#12436
Add a `graphviz` crate for making .dot files to layout and render graphs.
(This is a precursor to other work to render control-flow graphs from within rustc itself; but this crate should be independently usable, since it abstracts over the client's graph-representation and labeling method.)
By carefully distinguishing falling back to the default arm from moving
on to the next pattern, this patch adjusts the codegen logic for range
and guarded arms of pattern matching expression. It is a more
appropriate way of fixing #12582 and #13027 without causing regressions
such as #13867.
Closes#13867
Some cases were not correctly handled by this lint, for instance `let a = 42u8; a < 0` and `let a = 42u8; a > 255`.
It led to the discovery of two useless comparisons, which I removed.
Turning a `&T` into an `&mut T` carries a large risk of undefined
behaviour, and needs to be done very very carefully. Providing a
convenience function for exactly this task is a bad idea, just tempting
people into doing the wrong thing.
The right thing is to use types like `Cell`, `RefCell` or `Unsafe`.
For memory safety, Rust has that guarantee that `&mut` pointers do not
alias with any other pointer, that is, if you have a `&mut T` then that
is the only usable pointer to that `T`. This allows Rust to assume that
writes through a `&mut T` do not affect the values of any other `&` or
`&mut` references. `&` pointers have no guarantees about aliasing or
not, so it's entirely possible for the same pointer to be passed into
both arguments of a function like
fn foo(x: &int, y: &int) { ... }
Converting either of `x` or `y` to a `&mut` pointer and modifying it
would affect the other value: invalid behaviour.
(Similarly, it's undefined behaviour to modify the value of an immutable
local, like `let x = 1;`.)
At a low-level, the *only* safe way to obtain an `&mut` out of a `&` is
using the `Unsafe` type (there are higher level wrappers around it, like
`Cell`, `RefCell`, `Mutex` etc.). The `Unsafe` type is registered with
the compiler so that it can reason a little about these `&` to `&mut`
casts, but it is still up to the user to ensure that the `&mut`s
obtained out of an `Unsafe` never alias.
(Note that *any* conversion from `&` to `&mut` can be invalid, including
a plain `transmute`, or casting `&T` -> `*T` -> `*mut T` -> `&mut T`.)
[breaking-change]
Most of the links I've removed are for types that don't exist anymore with the exception of `SendReceiver` though I'm not sure how useful it is to link to that without the accompanying `Receiver` and `Sender` and I don't know how useful those links are when they're discussed below and `channel`/`sync_channel` is on the `std::comm` page already linked.
Previously, windows was using the CREATE_NEW flag which fails if the file
previously existed, which differed from the unix semantics. This alters the
opening to use the OPEN_ALWAYS flag to mirror the unix semantics.
Closes#13861
This has long since not been too relevant since the introduction of many crate
type outputs. This commit removes the flag entirely, adjusting all logic to do
the most reasonable thing when building both a library and an executable.
Closes#13337
Improve tutorial discussion of closures, e.g. with respect to type inference and variable capture.
Fix#13621
---- original description follows
I'd like this pulled to master if possible but if not I'd appreciate comments on what I need to change. I found the closures difficult to understand as they were so I tried to explain it so I would've had an easier time understanding it. I think it's better at least, somewhat.
I don't know that everyone liked the `-> ()` I included but I thought explicit is best to aid understanding. I thought it was much harder to understand than it should have been.
[EDIT] - Clicked too early.
This doesn't `make check` without errors on my Xubuntu on Virtualbox machine. Not sure why. I don't think I changed anything problematic. I'll try `make check` on master tomorrow.
Opened https://github.com/mozilla/rust/issues/13621 regarding this.
- using libgreen to optimize CPU usage
- less tasks to limit wasted resources
Here, on a one core 2 threads CPU, new version is ~1.2 faster. May
be better with more core.
This was removed because these could alias with `&const T` or `@mut T`
and those are now gone from the language. There are still aliasing
issues within local scopes, but this is correct for function parameters.
This also removes the no-op `noalias` marker on proc (not a pointer) and
leaves out the mention of #6750 because real type-based alias analysis
is not within the scope of best effort usage of the `noalias` attribute.
Test case:
pub fn foo(x: &mut &mut u32) {
**x = 5;
**x = 5;
}
Before:
define void @_ZN3foo20h0ce94c9671b0150bdaa4v0.0E(i32** nocapture readonly) unnamed_addr #0 {
entry-block:
%1 = load i32** %0, align 8
store i32 5, i32* %1, align 4
%2 = load i32** %0, align 8
store i32 5, i32* %2, align 4
ret void
}
After:
define void @_ZN3foo20h0ce94c9671b0150bdaa4v0.0E(i32** noalias nocapture readonly) unnamed_addr #0 {
entry-block:
%1 = load i32** %0, align 8
store i32 5, i32* %1, align 4
ret void
}
Closes#12436
The years of copyright and the name of the copyright holder were not
present in the notice.
The Apache license was added to the project in 2012, so 2012 is the
starting year. The copyright holder is the Mozilla Foundation (taken
from the MIT license).
This ensures that private functions exported through static initializers will
actually end up being public in the object file (so other objects can continue
to reference the function).
Closes#13620
- using libgreen to optimize CPU usage
- less tasks to limit wasted resources
Here, on a one core 2 threads CPU, new version is ~1.2 faster. May
be better with more core.
Closes#7575.
I don't think the change from a contains lookup to an iteration of the HashSet in the resolver should be much of a burden as the set of methods with the same name should be relatively small.
