borrowck: consolidate `mut` suggestions
This converts all of borrowck's `mut` suggestions to a new
`mc::ImmutabilityBlame` API instead of the current mix of various hacks.
Fixes#35937.
Fixes#40823.
Fixes#40859.
cc @estebank
r? @pnkfelix
This converts all of borrowck's `mut` suggestions to a new
`mc::ImmutabilityBlame` API instead of the current mix of various hacks.
Fixes#35937.
Fixes#40823.
This commit deletes the internal liblog in favor of the implementation that
lives on crates.io. Similarly it's also setting a convention for adding crates
to the compiler. The main restriction right now is that we want compiler
implementation details to be unreachable from normal Rust code (e.g. requires a
feature), and by default everything in the sysroot is reachable via `extern
crate`.
The proposal here is to require that crates pulled in have these lines in their
`src/lib.rs`:
#![cfg_attr(rustbuild, feature(staged_api, rustc_private))]
#![cfg_attr(rustbuild, unstable(feature = "rustc_private", issue = "27812"))]
This'll mean that by default they're not using these attributes but when
compiled as part of the compiler they do a few things:
* Mark themselves as entirely unstable via the `staged_api` feature and the
`#![unstable]` attribute.
* Allow usage of other unstable crates via `feature(rustc_private)` which is
required if the crate relies on any other crates to compile (other than std).
Point to let when modifying field of immutable variable
Point at the immutable local variable when trying to modify one of its
fields.
Given a file:
```rust
struct Foo {
pub v: Vec<String>
}
fn main() {
let f = Foo { v: Vec::new() };
f.v.push("cat".to_string());
}
```
present the following output:
```
error: cannot borrow immutable field `f.v` as mutable
--> file.rs:7:13
|
6 | let f = Foo { v: Vec::new() };
| - this should be `mut`
7 | f.v.push("cat".to_string());
| ^^^
error: aborting due to previous error
```
Fix#27593.
Drop of arrays is now translated in trans::block in an ugly way that I
should clean up in a later PR, and does not handle panics in the middle
of an array drop, but this commit & PR are growing too big.
Point at the immutable local variable when trying to modify one of its
fields.
Given a file:
```rust
struct Foo {
pub v: Vec<String>
}
fn main() {
let f = Foo { v: Vec::new() };
f.v.push("cat".to_string());
}
```
present the following output:
```
error: cannot borrow immutable field `f.v` as mutable
--> file.rs:7:13
|
6 | let f = Foo { v: Vec::new() };
| - this should be `mut`
7 | f.v.push("cat".to_string());
| ^^^
error: aborting due to previous error
```
A task function is now given as a `fn` pointer to ensure that it carries
no state. Each fn can take two arguments, because that worked out to be
convenient -- these two arguments must be of some type that is
`DepGraphSafe`, a new trait that is intended to prevent "leaking"
information into the task that was derived from tracked state.
This intentionally leaves `DepGraph::in_task()`, the more common form,
alone. Eventually all uses of `DepGraph::in_task()` should be ported
to `with_task()`, but I wanted to start with a smaller subset.
Originally I wanted to use closures bound by an auto trait, but that
approach has some limitations:
- the trait cannot have a `read()` method; since the current method
is unused, that may not be a problem.
- more importantly, we would want the auto trait to be "undefined" for all types
*by default* -- that is, this use case doesn't really fit the typical
auto trait scenario. For example, imagine that there is a `u32` loaded
out of a `hir::Node` -- we don't really want to be passing that
`u32` into the task!
This reduces the number of dynamic drops in libstd from 1141 to 899.
However, without this change, the next patch would have created much
more dynamic drops.
A basic merge unswitching hack reduced the number of dynamic drops to
644, with no effect on stack usage. I should be writing a more dedicated
drop unswitching pass.
No performance measurements.
Previously it used to build a switch in a way that didn’t preserve the invariat of SwitchInt. Now
it builds it in an optimal way too, where otherwise branch becomes all the branches which did not
have partial variant drops.
This removes another special case of Switch by replacing it with the more general SwitchInt. While
this is more clunky currently, there’s no reason we can’t make it nice (and efficient) to use.
Point to immutable arg/fields when trying to use as &mut
Present the following output when trying to access an immutable borrow's
field as mutable:
```
error[E0389]: cannot borrow data mutably in a `&` reference
--> $DIR/issue-38147-1.rs:27:9
|
26 | fn f(&self) {
| ----- use `&mut self` here to make mutable
27 | f.s.push('x');
| ^^^ assignment into an immutable reference
```
And the following when trying to access an immutable struct field as mutable:
```
error: cannot borrow immutable borrowed content `*self.s` as mutable
--> $DIR/issue-38147-3.rs:17:9
|
12 | s: &'a String
| ------------- use `&'a mut String` here to make mutable
...|
16 | fn f(&self) {
| ----- use `&mut self` here to make mutable
17 | self.s.push('x');
| ^^^^^^ cannot borrow as mutable
```
Fixes#38147.
Point to immutable borrow arguments and fields when trying to use them as
mutable borrows. Add label to primary span on "cannot borrow as mutable"
errors.
Present the following output when trying to access an immutable borrow's
field as mutable:
```
error[E0389]: cannot borrow data mutably in a `&` reference
--> $DIR/issue-38147-1.rs:27:9
|
26 | fn f(&self) {
| ----- use `&mut self` here to make mutable
27 | f.s.push('x');
| ^^^ assignment into an immutable reference
```
And the following when trying to access an immutable struct field as mutable:
```
error: cannot borrow immutable borrowed content `*self.s` as mutable
--> $DIR/issue-38147-3.rs:17:9
|
12 | s: &'a String
| ------------- use `&'a mut String` here to make mutable
...|
16 | fn f(&self) {
| ----- use `&mut self` here to make mutable
17 | self.s.push('x');
| ^^^^^^ cannot borrow as mutable
```
[11/n] Separate ty::Tables into one per each body.
_This is part of a series ([prev](https://github.com/rust-lang/rust/pull/38449) | [next]()) of patches designed to rework rustc into an out-of-order on-demand pipeline model for both better feature support (e.g. [MIR-based](https://github.com/solson/miri) early constant evaluation) and incremental execution of compiler passes (e.g. type-checking), with beneficial consequences to IDE support as well.
If any motivation is unclear, please ask for additional PR description clarifications or code comments._
<hr>
In order to track the results of type-checking and inference for incremental recompilation, they must be stored separately for each function or constant value, instead of lumped together.
These side-`Tables` also have to be tracked by various passes, as they visit through bodies (all of which have `Tables`, even if closures share the ones from their parent functions). This is usually done by switching a `tables` field in an override of `visit_nested_body` before recursing through `visit_body`, to the relevant one and then restoring it - however, in many cases the nesting is unnecessary and creating the visitor for each body in the crate and then visiting that body, would be a much cleaner solution.
To simplify handling of inlined HIR & its side-tables, their `NodeId` remapping and entries HIR map were fully stripped out, which means that `NodeId`s from inlined HIR must not be used where a local `NodeId` is expected. It might be possible to make the nodes (`Expr`, `Block`, `Pat`, etc.) that only show up within a `Body` have IDs that are scoped to that `Body`, which would also allow `Tables` to use `Vec`s.
That last part also fixes#38790 which was accidentally introduced in a previous refactor.
Historically this was done to accommodate bugs in lints, but there hasn't been a
bug in a lint since this feature was added which the warnings affected. Let's
completely purge warnings from all our stages by denying warnings in all stages.
This will also assist in tracking down `stage0` code to be removed whenever
we're updating the bootstrap compiler.
