Rollup of 5 pull requests #69484
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Rollup of 5 pull requests #69484
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Usually, references to the interior are only created by the `Deref` and
`DerefMut` impl of the guards `Ref` and `RefMut`. Note that `RefCell`
already has to cope with leaks of such guards which, when it occurs,
effectively makes it impossible to ever acquire a mutable guard or any
guard for `Ref` and `RefMut` respectively. It is already safe to use
this to create a reference to the inner of the ref cell that lives as
long as the reference to the `RefCell` itself, e.g.
```rust
fn leak(r: &RefCell<usize>) -> Option<&usize> {
let guard = r.try_borrow().ok()?;
let leaked = Box::leak(Box::new(guard));
Some(&*leaked)
}
```
The newly added methods allow the same reference conversion without an
indirection over a leaked allocation and composing with both borrow and
try_borrow without additional method combinations.
The contents were always UTF-8 anyway, and &str has an equivalent representation to &[u8], so this should not affect performance while removing unsafety at edges. It may be worth exploring a further adjustment that stores a single byte (instead of 16) as the contents are always "", "-", or "+".
This prevents accidental dereferences and so forth of the Void type, as well as cleaning up the error message to reference Opaque rather than the more complicated PhantomData type.
Currently, function items are always tagged unnamed_addr, which means that casting a function to a function pointer is not guaranteed to produce a deterministic address. However, once a function pointer is created, we do expect that to remain stable. So, this changes the show_usize function to a static containing a function pointer and uses that for comparisons. Notably, a *static* may have 'unstable' address, but the function pointer within it must be constant. Resolves issue 58320.
Currently, it is only set correctly in the sanity checking implicit default fallback code. Having a config file at all will for force `no_std = false`.
instead of a hand rolled one.
Background: targets can be specied with or without config files; unneccessarily differences in the logic between those cases has caused a) the bug I tried to fix in the previous commit, b) the bug I introduced in the previous commit. The solution is to make the code paths the same as much as possible. 1. Targets are now not created from the `default` method. (I would both remove the impl if this was a public library, but just wrap it for convience becaues it's not.) Instead, there is a `from_triple` method which does the defaulting. 2. Besides the sanity checking, use the new method in the code reading config files. Now `no_std` is overriden iff set explicitly just like the other fields which are optional in the TOML AST type. 3. In sanity checking, just populate the map for all targets no matter what. That way do don't duplicate logic trying to be clever and remember which targets have "non standard" overrides. Sanity checking is back to just sanity checking, and out of the game of trying to default too.
…tolnay
Add methods to 'leak' RefCell borrows as references with the lifetime of the original reference
Usually, references to the interior are only created by the `Deref` and
`DerefMut` impl of the guards `Ref` and `RefMut`. Note that `RefCell`
already has to cope with leaks of such guards which, when it occurs,
effectively makes it impossible to ever acquire a mutable guard or any
guard for `Ref` and `RefMut` respectively. It is already safe to use
this to create a reference to the inner of the ref cell that lives as
long as the reference to the `RefCell` itself, e.g.
```rust
fn leak(r: &RefCell<usize>) -> Option<&usize> {
let guard = r.try_borrow().ok()?;
let leaked = Box::leak(Box::new(guard));
Some(&*leaked)
}
```
The newly added methods allow the same reference conversion without an
indirection over a leaked allocation. It's placed on the `Ref`/`RefMut` to
compose with both borrow and try_borrow directly.
…lnay Miscellaneous cleanup to formatting Each commit stands alone. This pull request will also resolve rust-lang#58320.
…Simulacrum Allow getting `no_std` from the config file Currently, it is only set correctly in the sanity checking implicit default fallback code. Having a config file at all will for force `no_std = false`.
rustc_metadata: Use binary search from standard library instead of a hand rolled one. Noticed while reviewing rust-lang#68941.
…bank Minor refactoring of statement parsing Extracted out of rust-lang#69445. r? @estebank
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@bors r+ rollup=never p=5 |
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📌 Commit ae383e2 has been approved by |
bors
added
the
S-waiting-on-bors
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☀️ Test successful - checks-azure |
This was referenced Feb 26, 2020
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Successful merges:
no_stdfrom the config file #69381 (Allow gettingno_stdfrom the config file)Failed merges:
r? @ghost