Fix trait solving ICEs
- Selection candidates that are known to be applicable are preferred
over candidates that are not.
- Don't ICE if a projection/object candidate is no longer applicable
(this can happen due to cycles in normalization)
- Normalize supertraits when finding trait object candidates
Closes#77653Closes#77656
r? `@nikomatsakis`
Mark inout asm! operands as used in liveness pass
Variables used in `inout` operands in inline assembly (that is, they're used as both input and output to some arbitrary assembly instruction) are being marked as read and written, but are not marked as being used in the RWU table during the liveness pass. This can result in such expressions triggering an unused variable lint warning. This is incorrect behavior- reads without uses are currently only used for compound assignments. We conservatively assume that an `inout` operand is being read and used in the context of the assembly instruction.
Closes#77915
Support signed integers and `char` in v0 mangling
Likely we want more tests, to check the output is correct too: however, I wasn't sure what kind of test we needed, so I just added one similar to that added in https://github.com/rust-lang/rust/pull/77452 for now.
r? @eddyb
This allows us to avoid synthesizing tokens in `prepend_attr`, since we
have the original tokens available.
We still need to synthesize tokens when expanding `cfg_attr`,
but this is an unavoidable consequence of the syntax of `cfg_attr` -
the user does not supply the `#` and `[]` tokens that a `cfg_attr`
expands to.
Calculate visibilities once in resolve
Then use them through a query based on resolver outputs.
Item visibilities were previously calculated in three places - initially in `rustc_resolve`, then in `rustc_privacy` during type privacy checkin, and then in `rustc_metadata` during metadata encoding.
The visibility logic is not entirely trivial, especially for things like constructors or enum variants, and all of it was duplicated.
This PR deduplicates all the visibility calculations, visibilities are determined once during early name resolution and then stored in `ResolverOutputs` and are later available through `tcx` as a query `tcx.visibility(def_id)`.
(This query existed previously, but only worked for other crates.)
Some special cases (e.g. visibilities for closure types, which are needed for type privacy checking) are not processed in resolve, but deferred and performed directly in the query instead.
Cycles in normalization can cause evaluations to change from Unknown to
Err. This means that some selection that were applicable no longer are.
To avoid this:
* Selection candidates that are known to be applicable are prefered
over candidates that are not.
* We don't ICE if a candidate is no longer applicable.
allow_internal_unstable is currently used
to side-step feature gate and stability checks.
While it was originally only meant to be used
only on macros, its use was expanded to
const functions.
This commit prepares stricter checks for the usage of allow_internal_unstable (only on macros)
and introduces the rustc_allow_const_fn_unstable attribute for usage on functions.
See rust-lang/rust#69399
Improve wording of "cannot multiply" type error
For example, if you had this code:
fn foo(x: i32, y: f32) -> f32 {
x * y
}
You would get this error:
error[E0277]: cannot multiply `f32` to `i32`
--> src/lib.rs:2:7
|
2 | x * y
| ^ no implementation for `i32 * f32`
|
= help: the trait `Mul<f32>` is not implemented for `i32`
However, that's not usually how people describe multiplication. People
usually describe multiplication like how the division error words it:
error[E0277]: cannot divide `i32` by `f32`
--> src/lib.rs:2:7
|
2 | x / y
| ^ no implementation for `i32 / f32`
|
= help: the trait `Div<f32>` is not implemented for `i32`
So that's what this change does. It changes this:
error[E0277]: cannot multiply `f32` to `i32`
--> src/lib.rs:2:7
|
2 | x * y
| ^ no implementation for `i32 * f32`
|
= help: the trait `Mul<f32>` is not implemented for `i32`
To this:
error[E0277]: cannot multiply `i32` by `f32`
--> src/lib.rs:2:7
|
2 | x * y
| ^ no implementation for `i32 * f32`
|
= help: the trait `Mul<f32>` is not implemented for `i32`
The optimization introduces additional uses of the discriminant operand, but
does not ensure that it is still valid to evaluate it or that it still
evaluates to the same value.
Evaluate it once at original position, and store the result in a new temporary.
