Remove the old AST-based backend from rustc_trans.
Starting with Rust 1.13, `--disable-orbit` , `-Z orbit=off` and `#[rustc_no_mir]` have been removed.
Only the new MIR backend is left in the compiler, and only early const_eval uses ASTs from other crates.
Filling drop (previously "zeroing drop"), `#[unsafe_no_drop_flag]` and associated unstable APIs are gone.
Implementing `Drop` doesn't add a flag anymore to the type, all of the dynamic drop is function local.
This is a [breaking-change], please use `Option::None` and/or `mem::forget` if you are unsure about your ability to prevent/control the drop of a value. In the future, `union` will be usable in some such cases.
**NOTE**: DO NOT MERGE before we get the new beta as the stage0, there's some cruft to remove.
All of this will massively simplify any efforts to implement (and as such it blocks) features such as `union`s, safe use of `#[packed]` or new type layout optimizations, not to mention many other experiments.
compute and cache HIR hashes at beginning
This avoids the compile-time overhead of computing them twice. It also fixes
an issue where the hash computed after typeck is differen than the hash before,
because typeck mutates the def-map in place.
Fixes#35549.
Fixes#35593.
Some performance measurements suggest this `HashesMap` is very small in memory (unobservable via `-Z time-passes`) and very cheap to construct. I do see some (very minor) performance wins in the incremental case after the first run -- the first run costs more because loading the dep-graph didn't have any hashing to do in that case. Example timings from two runs of `libsyntex-syntax` -- the (1) indicates first run, (2) indicates second run, and (*) indicates both together:
| Phase | Master | Branch |
| ---- | ---- | ---- |
| compute_hashes_map (1) | N/A | 0.343 |
| load_dep_graph (1) | 0 | 0 |
| serialize dep graph (1) | 4.190 | 3.920 |
| total (1) | 4.190 | 4.260 |
| compute_hashes_map (2) | N/A | 0.344 |
| load_dep_graph (2) | 0.592 | 0.252 |
| serialize dep graph (2) | 4.119 | 3.779 |
| total (2) | 4.71 | 4.375 |
| total (*) | 8.9 | 8.635 |
r? @michaelwoerister
Carrier trait (third attempt)
This adds a `Carrier` trait to operate with `?`. The only public implementation is for `Result`, so effectively the trait does not exist, however, it ensures future compatibility for the `?` operator. This is not intended to be used, nor is it intended to be a long-term solution.
Although this exact PR has not been through Crater, I do not expect it to be a breaking change based on putting numerous similar PRs though Crater in the past.
cc:
* [? tracking issue](https://github.com/rust-lang/rust/issues/31436)
* [previous PR](https://github.com/rust-lang/rust/pull/35056)
* [RFC issue](https://github.com/rust-lang/rfcs/issues/1718) for discussion of long-term Carrier trait solutions.
r? @nikomatsakis
Wording fixes in error messages
This PR is largely wording fixes to existing PRs that I found going back through the ones that have already been updated. Sometimes seeing the message in context made me think "oh there's a better wording!"
There's one additional fix. This will also prevent the secondary underlining of derive call (since they look like macros to the system in the way I was using):
```
error[E0184]: the trait `Copy` may not be implemented for this type; the type has a destructor
--> src/test/compile-fail/E0184.rs:11:10
|
11 | #[derive(Copy)] //~ ERROR E0184
| ^^^^
| |
| in this macro invocation
```
Is now just:
```
error[E0184]: the trait `Copy` may not be implemented for this type; the type has a destructor
--> src/test/compile-fail/E0184.rs:11:10
|
11 | #[derive(Copy)] //~ ERROR E0184
| ^^^^
```
rustdoc: remove the `!` from macro URLs and titles
Because the `!` is part of a macro use, not the macro's name. E.g., you write `macro_rules! foo` not `macro_rules! foo!`, also `#[macro_import(foo)]`.
(Pulled out of #35020).
This avoids the compile-time overhead of computing them twice. It also fixes
an issue where the hash computed after typeck is differen than the hash before,
because typeck mutates the def-map in place.
Fixes#35549.
Fixes#35593.
Specific error message for missplaced doc comments
Identify when documetation comments have been missplaced in the following places:
* After a struct element:
```rust
// file.rs:
struct X {
a: u8 /** document a */,
}
```
```bash
$ rustc file.rs
file.rs:2:11: 2:28 error: found documentation comment that doesn't
document anything
file.rs:2 a: u8 /** document a */,
^~~~~~~~~~~~~~~~~
file.rs:2:11: 2:28 help: doc comments must come before what they document,
maybe a comment was intended with `//`?
```
* As the last line of a struct:
```rust
// file.rs:
struct X {
a: u8,
/// incorrect documentation
}
```
```bash
$ rustc file.rs
file.rs:3:5: 3:27 error: found a documentation comment that doesn't
document anything
file.rs:3 /// incorrect documentation
^~~~~~~~~~~~~~~~~~~~~~
file.rs:3:5: 3:27 help: doc comments must come before what they document,
maybe a comment was intended with `//`?
```
* As the last line of a `fn`:
```rust
// file.rs:
fn main() {
let x = 1;
/// incorrect documentation
}
```
```bash
$ rustc file.rs
file.rs:3:5: 3:27 error: found a documentation comment that doesn't
document anything
file.rs:3 /// incorrect documentation
^~~~~~~~~~~~~~~~~~~~~~
file.rs:3:5: 3:27 help: doc comments must come before what they document,
maybe a comment was intended with `//`?
```
Fix#27429, #30322
