Fix incorrect trait bound restriction suggestion
Suggest
```
error[E0308]: mismatched types
--> $DIR/restrict-assoc-type-of-generic-bound.rs:9:12
|
LL | pub fn foo<A: MyTrait, B>(a: A) -> B {
| - - expected `B` because of return type
| |
| expected this type parameter
LL | return a.bar();
| ^^^^^^^ expected type parameter `B`, found associated type
|
= note: expected type parameter `B`
found associated type `<A as MyTrait>::T`
help: consider further restricting this bound
|
LL | pub fn foo<A: MyTrait<T = B>, B>(a: A) -> B {
| +++++++
```
instead of
```
error[E0308]: mismatched types
--> $DIR/restrict-assoc-type-of-generic-bound.rs:9:12
|
LL | pub fn foo<A: MyTrait, B>(a: A) -> B {
| - - expected `B` because of return type
| |
| expected this type parameter
LL | return a.bar();
| ^^^^^^^ expected type parameter `B`, found associated type
|
= note: expected type parameter `B`
found associated type `<A as MyTrait>::T`
help: consider further restricting this bound
|
LL | pub fn foo<A: MyTrait + <T = B>, B>(a: A) -> B {
| +++++++++
```
Fix#117501.
Pretty print `Fn` traits in `rustc_on_unimplemented`
I don't think that users really ever should need to think about `Fn*` traits' tupled args for a simple trait error.
r? diagnostics
Derive expansions for packed structs cause move errors because
they prefer copying over borrowing since borrowing the fields of a
packed struct can result in unaligned access and therefore undefined
behaviour.
This underlying cause of the errors, however, is not apparent
to the user. We add a diagnostic note here to remedy that.
Add all RPITITs when augmenting param-env with GAT bounds in `check_type_bounds`
When checking that associated type definitions actually satisfy their associated type bounds in `check_type_bounds`, we construct a "`normalize_param_env`" which adds a projection predicate that allows us to assume that we can project the GAT to the definition we're checking. For example, in:
```rust
type Foo {
type Bar: Display = i32;
}
```
We would add `<Self as Foo>::Bar = i32` as a projection predicate when checking that `i32: Display` holds.
That `normalize_param_env` was, for some reason, only being used to normalize the predicate before it was registered. This is sketchy, because a nested obligation may require the GAT bound to hold, and also the projection cache is broken and doesn't differentiate projection cache keys that differ by param-envs 😿.
This `normalize_param_env` is also not sufficient when we have nested RPITITs and default trait methods, since we need to be able to assume we can normalize both the RPITIT and all of its child RPITITs to sufficiently prove all of its bounds. This is the cause of #117104, which only starts to fail for RPITITs that are nested 3 and above due to the projection-cache bug above.[^1]
## First fix
Use the `normalize_param_env` everywhere in `check_type_bounds`. This is reflected in a test I've constructed that fixes a GAT-only failure.
## Second fix
For RPITITs, install projection predicates for each RPITIT in the same function in `check_type_bounds`. This fixes#117104.
not sure who to request, so...
r? `@lcnr` hehe feel free to reassign :3
[^1]: The projection cache bug specifically occurs because we try normalizing the `assumed_wf_types` with the non-normalization param-env. This causes us to insert a projection cache entry that keeps the outermost RPITIT rigid, and it trivially satisifes all its own bounds. Super sketchy![^2]
[^2]: I haven't actually gone and fixed the projection cache bug because it's only marginally related, but I could, and it should no longer be triggered here.
Suggest
```
error[E0308]: mismatched types
--> $DIR/restrict-assoc-type-of-generic-bound.rs:9:12
|
LL | pub fn foo<A: MyTrait, B>(a: A) -> B {
| - - expected `B` because of return type
| |
| expected this type parameter
LL | return a.bar();
| ^^^^^^^ expected type parameter `B`, found associated type
|
= note: expected type parameter `B`
found associated type `<A as MyTrait>::T`
help: consider further restricting this bound
|
LL | pub fn foo<A: MyTrait<T = B>, B>(a: A) -> B {
| +++++++
```
instead of
```
error[E0308]: mismatched types
--> $DIR/restrict-assoc-type-of-generic-bound.rs:9:12
|
LL | pub fn foo<A: MyTrait, B>(a: A) -> B {
| - - expected `B` because of return type
| |
| expected this type parameter
LL | return a.bar();
| ^^^^^^^ expected type parameter `B`, found associated type
|
= note: expected type parameter `B`
found associated type `<A as MyTrait>::T`
help: consider further restricting this bound
|
LL | pub fn foo<A: MyTrait + <T = B>, B>(a: A) -> B {
| +++++++++
```
Fix#117501.
Remove support for alias `-Z symbol-mangling-version`
(This is very similar to the removal of `-Z instrument-coverage` in #117111.)
`-C symbol-mangling-version` was stabilized back in rustc 1.59.0 (2022-02-24) via #90128, with the old unstable flag kept around (with a warning) as an alias to ease migration.
use global cache when computing proof trees
we're writing the solver while relying on the existence of the global cache to avoid exponential blowup. By disabling the global cache when building proof trees, it is easy to get hangs, e.g. when computing intercrate ambiguity causes.
Removes the unstable `-Zdump_solver_proof_tree_use_cache` option, as we now always return a full proof tree.
r? `@compiler-errors`
Don't check for alias bounds in liveness when aliases have escaping bound vars
I actually have no idea how we *should* be treating aliases with escaping bound vars here... but the simplest behavior is just doing what we used to do before.
r? aliemjay
Fixes#117455
Most notably, this commit changes the `pub use crate::*;` in that file
to `use crate::*;`. This requires a lot of `use` items in other crates
to be adjusted, because everything defined within `rustc_span::*` was
also available via `rustc_span::source_map::*`, which is bizarre.
The commit also removes `SourceMap::span_to_relative_line_string`, which
is unused.
The comment just below the first one describes how the `impl !Send for
FatalError` makes it impossible to `panic!(FatalError)`.
And the second one should be `panic_any` instead of `panic!`.
