diagnostics: shorten paths of unique symbols
This is a step towards implementing a fix for #50310, and continuation of the discussion in [Pre-RFC: Nicer Types In Diagnostics - compiler - Rust Internals](https://internals.rust-lang.org/t/pre-rfc-nicer-types-in-diagnostics/11139). Impressed upon me from previous discussion in #21934 that an RFC for this is not needed, and I should just come up with code.
The recent improvements to `use` suggestions that I've contributed have given rise to this implementation. Contrary to previous suggestions, it's rather simple logic, and I believe it only reduces the amount of cognitive load that a developer would need when reading type errors.
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If a symbol name can only be imported from one place, and as long as it was not glob-imported anywhere in the current crate, we can trim its printed path to the last component.
This has wide implications on error messages with types, for example, shortening `std::vec::Vec` to just `Vec`, as long as there is no other `Vec` importable from anywhere.
If a symbol name can only be imported from one place for a type, and
as long as it was not glob-imported anywhere in the current crate, we
can trim its printed path and print only the name.
This has wide implications on error messages with types, for example,
shortening `std::vec::Vec` to just `Vec`, as long as there is no other
`Vec` importable anywhere.
This adds a new '-Z trim-diagnostic-paths=false' option to control this
feature.
On the good path, with no diagnosis printed, we should try to avoid
issuing this query, so we need to prevent trimmed_def_paths query on
several cases.
This change also relies on a previous commit that differentiates
between `Debug` and `Display` on various rustc types, where the latter
is trimmed and presented to the user and the former is not.
Currently, the def span of a funtion encompasses the entire function
signature and body. However, this is usually unnecessarily verbose - when we are
pointing at an entire function in a diagnostic, we almost always want to
point at the signature. The actual contents of the body tends to be
irrelevant to the diagnostic we are emitting, and just takes up
additional screen space.
This commit changes the `def_span` of all function items (freestanding
functions, `impl`-block methods, and `trait`-block methods) to be the
span of the signature. For example, the function
```rust
pub fn foo<T>(val: T) -> T { val }
```
now has a `def_span` corresponding to `pub fn foo<T>(val: T) -> T`
(everything before the opening curly brace).
Trait methods without a body have a `def_span` which includes the
trailing semicolon. For example:
```rust
trait Foo {
fn bar();
}```
the function definition `Foo::bar` has a `def_span` of `fn bar();`
This makes our diagnostic output much shorter, and emphasizes
information that is relevant to whatever diagnostic we are reporting.
We continue to use the full span (including the body) in a few of
places:
* MIR building uses the full span when building source scopes.
* 'Outlives suggestions' use the full span to sort the diagnostics being
emitted.
* The `#[rustc_on_unimplemented(enclosing_scope="in this scope")]`
attribute points the entire scope body.
* The 'unconditional recursion' lint uses the full span to show
additional context for the recursive call.
All of these cases work only with local items, so we don't need to
add anything extra to crate metadata.
This is a re-attempt of #72389 (which was reverted in #73594)
Instead of using `ExpnKind::Desugaring` to represent operators, this PR
checks the lang item directly.
Explain move errors that occur due to method calls involving `self`
When calling a method that takes `self` (e.g. `vec.into_iter()`), the method receiver is moved out of. If the method receiver is used again, a move error will be emitted::
```rust
fn main() {
let a = vec![true];
a.into_iter();
a;
}
```
emits
```
error[E0382]: use of moved value: `a`
--> src/main.rs:4:5
|
2 | let a = vec![true];
| - move occurs because `a` has type `std::vec::Vec<bool>`, which does not implement the `Copy` trait
3 | a.into_iter();
| - value moved here
4 | a;
| ^ value used here after move
```
However, the error message doesn't make it clear that the move is caused by the call to `into_iter`.
This PR adds additional messages to move errors when the move is caused by using a value as the receiver of a `self` method::
```
error[E0382]: use of moved value: `a`
--> vec.rs:4:5
|
2 | let a = vec![true];
| - move occurs because `a` has type `std::vec::Vec<bool>`, which does not implement the `Copy` trait
3 | a.into_iter();
| ------------- value moved due to this method call
4 | a;
| ^ value used here after move
|
note: this function takes `self`, which moves the receiver
--> /home/aaron/repos/rust/src/libcore/iter/traits/collect.rs:239:5
|
239 | fn into_iter(self) -> Self::IntoIter;
```
TODO:
- [x] Add special handling for `FnOnce/FnMut/Fn` - we probably don't want to point at the unstable trait methods
- [x] Consider adding additional context for operations (e.g. `Shr::shr`) when the call was generated using the operator syntax (e.g. `a >> b`)
- [x] Consider pointing to the method parent (impl or trait block) in addition to the method itself.
Moving more build-pass tests to check-pass
One or two tests became build-pass without the FIXME because they really
needed build-pass (were failing without it).
Helps with #62277
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They used to be covered by `optin_builtin_traits` but negative impls
are now applicable to all traits, not just auto traits.
This also adds docs in the unstable book for the current state of auto traits.
This change makes error and warning annotations mandatory in UI tests.
The only exception are tests that use error patterns to match compiler
output and don't have any annotations.
Adds a new ABI for the EFIAPI calls. This ABI should reflect the latest
version of the UEFI specification at the time of commit (UEFI spec 2.8,
URL below). The specification says that for x86_64, we should follow the
win64 ABI, while on all other supported platforms (ia32, itanium, arm,
arm64 and risc-v), we should follow the C ABI.
To simplify the implementation, we will simply follow the C ABI on all
platforms except x86_64, even those technically unsupported by the UEFI
specification.
https://uefi.org/sites/default/files/resources/UEFI_Spec_2_8_final.pdf
This is based on the feedback from estebank:
"""
I believe that test can be removed outright. It'd be impossible for a
new change to go through that breaks this kind of output without it
being picked up by multiple other `stderr` tests. This is an artifact
of the transition period to the "new" output style.
"""
see: https://github.com/rust-lang/rust/issues/52663#issuecomment-422155551
Give a special message when the later use is from a call. Use the span
of the callee instead of the whole expression. For conflicting borrow
messages say that the later use is of the first borrow.
* Arguably this change is sometimes injecting noise into the output
(namely in the cases where the suggested rewrite is inline with the
suggestion and we end up highlighting the original source code).
I would not be opposed to something more aggressive/dynamic, like
revising the suggestion code to automatically print the original
source when necessary (e.g. when the error does not have a span
that includes the span of the suggestion).
* Also, as another note on this change: The doc comment for `Diagnostic::span_suggestion`
says:
/// The message
///
/// * should not end in any punctuation (a `:` is added automatically)
/// * should not be a question
/// * should not contain any parts like "the following", "as shown"
but the `:` is *not* added when the emitted line appears
out-of-line relative to the suggestion. I find that to be an
unfortunate UI experience.
----
As a drive-by fix, also changed code to combine multiple suggestions
for a pattern into a single multipart suggestion (which vastly
improves user experience IMO).
----
Includes the updates to expected NLL diagnostics.
