This warning kind of snuck up on us! (See #748) For now, let's
disable it. (I've cleaned it up in a couple of examples, since
those are meant to be more idiomatic and user-facing.)
Closes#748.
The feature we want is `#[doc = include_str!("README.md")]`, which is
stable since 1.54 and our MSRV is now 1.56.
This commit is precisely the result of the following Perl rune:
perl -i~ -0777 -pe 's{(^//!(?!.*\@\@).*\n)+}{#![doc = include_str!("../README.md")]\n}m' crates/*/src/lib.rs
This should save around 1MB per consensus, since every relay has a
'protocols' lines, but there are only a few distinct possibilities
for such a line.
Closes#385.
This lint is IMO inherently ill-conceived.
I have looked for the reasons why this might be thought to be a good
idea and there were basically two (and they are sort of contradictory):
I. "Calling ‘.clone()` on an Rc, Arc, or Weak can obscure the fact
that only the pointer is being cloned, not the underlying data."
This is the wording from
https://rust-lang.github.io/rust-clippy/v0.0.212/#clone_on_ref_ptr
It is a bit terse; we are left to infer why it is a bad idea to
obscure this fact. It seems to me that if it is bad to obscure some
fact, that must be because the fact is a hazard. But why would it be
a hazard to not copy the underlying data ?
In other languages, faliing to copy the underlying data is a serious
correctness hazard. There is a whose class of bugs where things were
not copied, and then mutated and/or reused in multiple places in ways
that were not what the programmer intended. In my experience, this is
a very common bug when writing Python and Javascript. I'm told it's
common in golang too.
But in Rust this bug is much much harder to write. The data inside an
Arc is immutable. To have this bug you'd have use interior mutability
- ie mess around with Mutex or RefCell. That provides a good barrier
to these kind of accidents.
II. "The reason for writing Rc::clone and Arc::clone [is] to make it
clear that only the pointer is being cloned, as opposed to the
underlying data. The former is always fast, while the latter can
be very expensive depending on what is being cloned."
This is the reasoning found here
https://github.com/rust-lang/rust-clippy/issues/2048
This is saying that *not* using Arc::clone is hazardous.
Specifically, that a deep clone is a performance hazard.
But for this argument, the lint is precisely backwards. It's linting
the "good" case and asking for it to be written in a more explicit
way; while the supposedly bad case can be written conveniently.
Also, many objects (in our codebase, and in all the libraries we use)
that are Clone are in fact simply handles. They contain Arc(s) (or
similar) and are cheap to clone. Indeed, that is the usual case.
It does not make sense to distinguish in the syntax we use to clone
such a handle, whether the handle is a transparent Arc, or an opaque
struct containing one or more other handles.
Forcing Arc::clone to be written as such makes for code churn when a
type is changed from Arc<Something> to Something: Clone, or vice
versa.
This error type doesn't impement HasKind, since the kind will depend
on context.
However, the existing implementation was pretty messy and inconsistent:
Some errors had positions, some didn't.
Some took messages as str, some as String.
Some had internal errors that were somewhat orthogonal to their actual
types.
This commit refactors tor_netdoc::Error to use a ParseErrorKind, and
adds a set of convenience functions to add positions and
messages to the errors that need them.
Nick Mathewson
Ian Jackson
trinity-1686a
Daniel Eades