This considerably simplifies code around calling functions and translation of Resume itself. This
removes requirement that a block containing Resume terminator is always translated after something
which creates a landing pad, thus allowing us to actually translate some valid MIRs we could not
translate before.
However, an assumption is added that translator is correct (in regards to landing pad generation)
and code will never reach the Resume terminator without going through a landing pad first. Breaking
these assumptions would pass an `undef` value into the personality functions.
This merges two separate Call terminators and uses a separate CallKind sub-enum instead.
A little bit unrelatedly, copying into destination value for a certain kind of invoke, is also
implemented here. See the associated comment in code for various details that arise with this
implementation.
DivergingCall is different enough from the regular converging Call to warrant the split. This also
inlines CallData struct and creates a new CallTargets enum in order to have a way to differentiate
between calls that do not have an associated cleanup block.
Note, that this patch still does not produce DivergingCall terminator anywhere. Look for that in
the next patches.
So far, calls going through `Fn::call`, `FnMut::call_mut`, or `FnOnce::call_once` have not been translated properly into MIR:
The call `f(a, b, c)` where `f: Fn(T1, T2, T3)` would end up in MIR as:
```
call `f` with arguments `a`, `b`, `c`
```
What we really want is:
```
call `Fn::call` with arguments `f`, `a`, `b`, `c`
```
This PR transforms these kinds of overloaded calls during `HIR -> HAIR` translation.
What's still a bit funky is that the `Fn` traits expect arguments to be tupled but due to special handling type-checking and trans, we do not actually tuple arguments and everything still checks out fine. So, after this PR we end up with MIR containing calls where function signature and arguments seemingly don't match:
```
call Fn::call(&self, args: (T1, T2, T3)) with arguments `f`, `a`, `b`, `c`
```
instead of
```
call Fn::call(&self, args: (T1, T2, T3)) with arguments `f`, (`a`, `b`, `c`) // <- args tupled!
```
It would be nice if the call traits could go without special handling in MIR and later on.
random tables. The old code was weird anyway because it would
potentially walk traits from other crates etc. The new code fits
seamlessly with the dependency tracking.
Rust differs in that behavior from C: In C, the newline escapes are resolved
before anything else, and in Rust this depends on whether the backslash is
escaped itself.
A difference can be observed in the following two programs:
```c
#include <stdio.h>
int main()
{
printf("\\
n\n");
return 0;
}
```
```rust
fn main() {
println!("\\
n");
}
```
The first program prints two newlines, the second one prints a backslash, a
newline, the latin character n and a final newline.
Some history:
While getting Rust to 1.0, it was a struggle to keep the book in a
working state. I had always wanted a certain kind of TOC, but couldn't
quite get it there.
At the 11th hour, I wrote up "Rust inside other langauges" and "Dining
Philosophers" in an attempt to get the book in the direction I wanted to
go. They were fine, but not my best work. I wanted to further expand
this section, but it's just never going to end up happening. We're doing
the second draft of the book now, and these sections are basically gone
already.
Here's the issues with these two sections, and removing them just fixes
it all:
// Philosophers
There was always controversy over which ones were chosen, and why. This
is kind of a perpetual bikeshed, but it comes up every once in a while.
The implementation was originally supposed to show off channels, but
never did, due to time constraints. Months later, I still haven't
re-written it to use them.
People get different results and assume that means they're wrong, rather
than the non-determinism inherent in concurrency. Platform differences
aggrivate this, as does the exact amount of sleeping and printing.
// Rust Inside Other Languages
This section is wonderful, and shows off a strength of Rust. However,
it's not clear what qualifies a language to be in this section. And I'm
not sure how tracking a ton of other languages is gonna work, into the
future; we can't test _anything_ in this section, so it's prone to
bitrot.
By removing this section, and making the Guessing Game an initial
tutorial, we will move this version of the book closer to the future
version, and just eliminate all of these questions.
In addition, this also solves the 'split-brained'-ness of having two
paths, which has endlessly confused people in the past.
I'm sad to see these sections go, but I think it's for the best.
Fixes#30471Fixes#30163Fixes#30162Fixes#25488Fixes#30345Fixes#29590Fixes#28713Fixes#28915
And probably others. This lengthy list alone is enough to show that
these should have been removed.
RIP.
Make `".".parse::<f32>()` and `".".parse::<f64>()` return Err
This fixes#30344.
This is a [breaking-change], which the libs team have classified as a
bug fix.
