Python script PEP8 style guide space formatting and minor Python source cleanup
This PR includes the following changes in the Python sources based on a flake8 3.7.9 (mccabe: 0.6.1, pycodestyle: 2.5.0, pyflakes: 2.1.1) CPython 3.7.6 on Darwin lint:
- PEP8 style guide spacing updates *without* line length changes
- removal of unused local variable assignments in context managers and exception handling
- removal of unused Python import statements
- removal of unnecessary semicolons
Test failure of unchecked arithmetic intrinsics in const eval
Test that the unchecked arithmetic intrinsics that were made unstably const in #68809 emit an error during const-eval if given invalid input.
Addresses [this comment](https://github.com/rust-lang/rust/pull/68809#discussion_r375753066).
r? @RalfJung
[experiment] Support linking from a .rlink file
Flag `-Z no-link` was previously introduced, which allows creating an `.rlink` file to perform compilation without linking. This change enables linking from an `.rlink` file.
Part of Issue #64191
This makes it faster and also changes it to a safe function. (Thanks to
Michael Woerister for the suggestion.) `load_int_le!` is also no longer
necessary.
When encountering E0212, detect whether this is a representable case or
not, i.e. if it's happening on an `fn` or on an ADT. If the former,
provide a structured suggestion, otherwise note that this can't be
represented in Rust.
Don't rustfmt check the vendor directory.
I need to be able to run `x.py tidy` to do license checks (which requires vendored dependencies). However, when vendoring is enabled, it wants to rustfmt check the entire vendor directory, which doesn't work.
Don't run coherence twice for future-compat lints
This fixes the regression introduced by https://github.com/rust-lang/rust/pull/65232 (which I mentioned in https://github.com/rust-lang/rust/pull/65232#issuecomment-583739037).
Old algorithm:
* Run coherence with all future-incompatible checks off, reporting errors on any overlap.
* If there's no overlap (common case), run it *again*, with the future-incompatible checks on. Report warnings for any overlap found.
New algorithm:
* Run coherence with all additional future-incompatible checks *on*, which means that we'll find *all* potentially overlapping impls immediately.
* If this found overlap, run coherence again, with the future-incompatible checks off. If that *still* gives an error, we report it. If not, it ought to be a warning.
This reduces time spent in coherence checking for the nrf52810-pac by roughly 50% relative to current master.
Use `dyn Trait` more in tests
Here are some tests using the old trait object type syntax which are not testing the syntax itself.
This has been extracted from https://github.com/rust-lang/rust/pull/66364.
traits: preallocate 2 Vecs of known initial size
The 2 preallocations are pretty obvious; both vectors will be as big as or larger than the collections they are created from.
In `WfPredicates::normalize` the change from a functional style improves readability and should be perf-friendly, too.
Enable Control Flow Guard in rustbuild
Now that Rust supports Control Flow Guard (#68180), add a config.toml option to build the standard library with CFG enabled.
r? @nagisa
