Provide hint when cast needs a dereference
For a given code:
``` rust
vec![0.0].iter().map(|s| s as i16).collect::<Vec<i16>>();
```
display:
``` nocode
error: casting `&f64` as `i16` is invalid
--> file3.rs:2:35
|
2 | vec![0.0].iter().map(|s| s as i16).collect::<Vec<i16>>();
| - ^^^
| |
| did you mean `*s`?
```
instead of:
``` nocode
error: casting `&f64` as `i16` is invalid
--> <anon>:2:30
|
2 | vec![0.0].iter().map(|s| s as i16).collect();
| ^^^^^^^^
|
= help: cast through a raw pointer first
```
Fixes#37338.
This implements RFC 1624, tracking issue #37339.
- `FnCtxt` (in typeck) gets a stack of `LoopCtxt`s, which store the
currently deduced type of that loop, the desired type, and a list of
break expressions currently seen. `loop` loops get a fresh type
variable as their initial type (this logic is stolen from that for
arrays). `while` loops get `()`.
- `break {expr}` looks up the broken loop, and unifies the type of
`expr` with the type of the loop.
- `break` with no expr unifies the loop's type with `()`.
- When building MIR, `loop` loops no longer construct a `()` value at
termination of the loop; rather, the `break` expression assigns the
result of the loop. `while` loops are unchanged.
- `break` respects contexts in which expressions may not end with braced
blocks. That is, `while break { break-value } { while-body }` is
illegal; this preserves backwards compatibility.
- The RFC did not make it clear, but I chose to make `break ()` inside
of a `while` loop illegal, just in case we wanted to do anything with
that design space in the future.
This is my first time dealing with this part of rustc so I'm sure
there's plenty of problems to pick on here ^_^
This changes structures like this:
```
[ ExprArray | 8 | P ]
|
v
[ P | P | P | P | P | P | P | P ]
|
v
[ ExprTup | 2 | P ]
|
v
[ P | P ]
|
v
[ Expr ]
```
to this:
```
[ ExprArray | 8 | P ]
|
v
[ [ ExprTup | 2 | P ] | ... ]
|
v
[ Expr | Expr ]
```
Clean up `ast::Attribute`, `ast::CrateConfig`, and string interning
This PR
- removes `ast::Attribute_` (changing `Attribute` from `Spanned<Attribute_>` to a struct),
- moves a `MetaItem`'s name from the `MetaItemKind` variants to a field of `MetaItem`,
- avoids needlessly wrapping `ast::MetaItem` with `P`,
- moves string interning into `syntax::symbol` (`ast::Name` is a reexport of `symbol::Symbol` for now),
- replaces `InternedString` with `Symbol` in the AST, HIR, and various other places, and
- refactors `ast::CrateConfig` from a `Vec` to a `HashSet`.
r? @eddyb
For a given code:
```rust
vec![0.0].iter().map(|s| s as i16).collect::<Vec<i16>>();
```
display:
```nocode
error: casting `&f64` as `i16` is invalid
--> foo.rs:2:35
|
2 | vec![0.0].iter().map(|s| s as i16).collect::<Vec<i16>>();
| - ^^^ cannot cast `&f64` as `i16`
| |
| did you mean `*s`?
```
instead of:
```nocode
error: casting `&f64` as `i16` is invalid
--> <anon>:2:30
|
2 | vec![0.0].iter().map(|s| s as i16).collect();
| ^^^^^^^^
|
= help: cast through a raw pointer first
```
Separate impl items from the parent impl
This change separates impl item bodies out of the impl itself. This gives incremental more resolution. In so doing, it refactors how the visitors work, and cleans up a bit of the collect/check logic (mostly by moving things out of collect that didn't really belong there, because they were just checking conditions).
However, this is not as effective as I expected, for a kind of frustrating reason. In particular, when invoking `foo.bar()` you still wind up with dependencies on private items. The problem is that the method resolution code scans that list for methods with the name `bar` -- and this winds up touching *all* the methods, even private ones.
I can imagine two obvious ways to fix this:
- separating fn bodies from fn sigs (#35078, currently being pursued by @flodiebold)
- a more aggressive model of incremental that @michaelwoerister has been advocating, in which we hash the intermediate results (e.g., the outputs of collect) so that we can see that the intermediate result hasn't changed, even if a particular impl item has changed.
So all in all I'm not quite sure whether to land this or not. =) It still seems like it has to be a win in some cases, but not with the test cases we have just now. I can try to gin up some test cases, but I'm not sure if they will be totally realistic. On the other hand, some of the early refactorings to the visitor trait seem worthwhile to me regardless.
cc #36349 -- well, this is basically a fix for that issue, I guess
r? @michaelwoerister
NB: Based atop of @eddyb's PR https://github.com/rust-lang/rust/pull/37402; don't land until that lands.
Before, when we created an AssociatedItem for impl item X, we would read
the impl item itself. Now we instead load up the impl I that contains X
and read the data from the `ImplItemRef` for X; actually, we do it for
all impl items in I pre-emptively.
This kills the last source of edges between a method X and a call to a
method Y defined in the same impl.
Fixes#37121
Add semicolon to "perhaps add a `use` for one of them" help
Similar to pull request #37430, this makes the message more copy-paste
friendly and aligns it with other messages like:
help: you can import it into scope: use foo::Bar;
r? @eddyb
coherence: skip impls with an erroneous trait ref
Impls with a erroneous trait ref are already ignored in the first part
of coherence, so ignore them in the second part too. This avoids
cascading coherence errors when 1 impl of a trait has an error.
r? @nikomatsakis
Refactoring towards region obligation
Two refactorings towards the intermediate goal of propagating region obligations through the `InferOk` structure (which in turn leads to the possibility of lazy normalization).
1. Remove `TypeOrigin` and add `ObligationCause`
- as we converge subtyping and obligations and so forth, the ability to keep these types distinct gets harder
2. Propagate obligations from `InferOk` into the surrounding fulfillment context
After these land, I have a separate branch (which still needs a bit of work) that can make the actual change to stop directly adding subregion edges and instead propagate obligations. (This should also make it easier to fix the unsoundness in specialization around lifetimes.)
r? @eddyb
This helps with incr. comp. because otherwise the Collect(Impl) check
winds up touching all of the impl items; since Collect(Impl) also
produces the types for the impl header, this creates a polluted graph
where the impl types depend on the impl items.
In general having all these different structs for "origins" is not
great, since equating types can cause obligations and vice-versa. I
think we should gradually collapse these things. We almost certainly
also need to invest a big more energy into the `error_reporting` code to
rationalize it: this PR does kind of the minimal effort in that
direction.
Similar to pull request #37430, this makes the message more copy-paste
friendly and aligns it with other messages like:
help: you can import it into scope: use foo::Bar;
Impls with a erroneous trait ref are already ignored in the first part
of coherence, so ignore them in the second part too. This avoids
cascading coherence errors when 1 impl of a trait has an error.
[8/n] rustc: clean up lookup_item_type and remove TypeScheme.
_This is part of a series ([prev](https://github.com/rust-lang/rust/pull/37676) | [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>
* `tcx.tcache` -> `tcx.item_types`
* `TypeScheme` (grouping `Ty` and `ty::Generics`) is removed
* `tcx.item_types` entries no longer duplicated in `tcx.tables.node_types`
* `tcx.lookup_item_type(def_id).ty` -> `tcx.item_type(def_id)`
* `tcx.lookup_item_type(def_id).generics` -> `tcx.item_generics(def_id)`
* `tcx.lookup_generics(def_id)` -> `tcx.item_generics(def_id)`
* `tcx.lookup_{super_,}predicates(def_id)` -> `tcx.item_{super_,}predicates(def_id)`
Make E0243/E0244 message consistent with E0107
E0243/E0233 prints `expected {}, found {}` on the span note, while E0107 prints it on the first line. This is confusing when both error occur simultaneously.
This PR makes E0243/E0233 print `expected {}, found {}` on the first line.
Code:
``` rust
struct Foo<'a, 'b> {
s: &'a str,
t: &'b str,
}
type Bar<T, U> = Foo<T, U>;
```
rustc output (before):
```
error[E0107]: wrong number of lifetime parameters: expected 2, found 0
--> test.rs:6:18
|
6 | type Bar<T, U> = Foo<T, U>;
| ^^^^^^^^^ expected 2 lifetime parameters
error[E0244]: wrong number of type arguments
--> test.rs:6:18
|
6 | type Bar<T, U> = Foo<T, U>;
| ^^^^^^^^^ expected no type arguments, found 2
```
rustc output (after):
```
error[E0107]: wrong number of lifetime parameters: expected 2, found 0
--> /tmp/test.rs:6:18
|
6 | type Bar<T, U> = Foo<T, U>;
| ^^^^^^^^^ expected 2 lifetime parameters
error[E0244]: wrong number of type arguments: expected 0, found 2
--> /tmp/test.rs:6:18
|
6 | type Bar<T, U> = Foo<T, U>;
| ^^^^^^^^^ expected no type arguments
```
