In this case, the exact extern crate isn't very important.
This is part of the changes needed to address the spurious failures from
a main test `../removing-extern-crate.rs` being both an auxiliary and a
main test file, causing fs races due to multiple `rustc` processes in
multiple test threads trying to build the main test file both as a main
test and also as an auxiliary at around the same time.
PR 138515, we insert a placeholder attribute so that checks for attributes can still know about the placement of `cfg` attributes. When we suggest removing items with `cfg_attr`s (fix Issue 56328) and make them verbose. We tweak the wording of the existing "unused `extern crate`" lint.
```
warning: unused extern crate
--> $DIR/removing-extern-crate.rs:9:1
|
LL | extern crate removing_extern_crate as foo;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ unused
|
note: the lint level is defined here
--> $DIR/removing-extern-crate.rs:6:9
|
LL | #![warn(rust_2018_idioms)]
| ^^^^^^^^^^^^^^^^
= note: `#[warn(unused_extern_crates)]` implied by `#[warn(rust_2018_idioms)]`
help: remove the unused `extern crate`
|
LL - #[cfg_attr(test, macro_use)]
LL - extern crate removing_extern_crate as foo;
LL +
|
```
```
error[E0610]: `{integer}` is a primitive type and therefore doesn't have fields
--> $DIR/attempted-access-non-fatal.rs:7:15
|
LL | let _ = 2.l;
| ^
|
help: if intended to be a floating point literal, consider adding a `0` after the period and a `f64` suffix
|
LL - let _ = 2.l;
LL + let _ = 2.0f64;
|
```
```
error[E0432]: unresolved import `some_novel_crate`
--> file.rs:1:5
|
1 | use some_novel_crate::Type;
| ^^^^^^^^^^^^^^^^ use of unresolved module or unlinked crate `some_novel_crate`
```
On resolve errors where there might be a missing crate, mention `cargo add foo`:
```
error[E0433]: failed to resolve: use of unresolved module or unlinked crate `nope`
--> $DIR/conflicting-impl-with-err.rs:4:11
|
LL | impl From<nope::Thing> for Error {
| ^^^^ use of unresolved module or unlinked crate `nope`
|
= help: if you wanted to use a crate named `nope`, use `cargo add nope` to add it to your `Cargo.toml`
```
When both `std::` and `core::` items are available, only suggest the
`std::` ones. We ensure that in `no_std` crates we suggest `core::`
items.
Ensure that the list of items suggested to be imported are always in the
order of local crate items, `std`/`core` items and finally foreign crate
items.
Tweak wording of import suggestion: if there are multiple items but they
are all of the same kind, we use the kind name and not the generic "items".
Fix#83564.
This commit does three things:
1. replaces (the last remaining) never true cfgs by the FALSE cfg
2. fix derive-helper-configured.rs (typo in directive)
3. and comment some current unused #[cfg_attr] (missing revisions)
Do not provide a structured suggestion when the arguments don't match.
```
error[E0599]: no method named `test_mut` found for struct `Vec<{integer}>` in the current scope
--> $DIR/auto-ref-slice-plus-ref.rs:7:7
|
LL | a.test_mut();
| ^^^^^^^^
|
= help: items from traits can only be used if the trait is implemented and in scope
note: `MyIter` defines an item `test_mut`, perhaps you need to implement it
--> $DIR/auto-ref-slice-plus-ref.rs:14:1
|
LL | trait MyIter {
| ^^^^^^^^^^^^
help: there is a method `get_mut` with a similar name, but with different arguments
--> $SRC_DIR/core/src/slice/mod.rs:LL:COL
```
Consider methods beyond inherent ones when suggesting typos.
```
error[E0599]: no method named `owned` found for reference `&dyn Foo` in the current scope
--> $DIR/object-pointer-types.rs:11:7
|
LL | fn owned(self: Box<Self>);
| --------- the method might not be found because of this arbitrary self type
...
LL | x.owned();
| ^^^^^ help: there is a method with a similar name: `to_owned`
```
Fix#101013.
macro_rules: Preserve all metavariable spans in a global side table
This PR preserves spans of `tt` metavariables used to pass tokens to declarative macros.
Such metavariable spans can then be used in span combination operations like `Span::to` to improve all kinds of diagnostics.
Spans of non-`tt` metavariables are currently kept in nonterminal tokens, but the long term plan is remove all nonterminal tokens from rustc parser and rely on the proc macro model with invisible delimiters (#114647, #67062).
In particular, `NtIdent` nonterminal (corresponding to `ident` metavariables) becomes easy to remove when this PR lands (#119412 does it).
The metavariable spans are kept in a global side table keyed by `Span`s of original tokens.
The alternative to the side table is keeping them in `SpanData` instead, but the performance regressions would be large because any spans from tokens passed to declarative macros would stop being inline and would work through span interner instead, and the penalty would be paid even if we never use the metavar span for the given original span.
(But also see the comment on `fn maybe_use_metavar_location` describing the map collision issues with the side table approach.)
There are also other alternatives - keeping the metavar span in `Token` or `TokenTree`, but associating it with `Span` itsel is the most natural choice because metavar spans are used in span combining operations, and those operations are not necessarily tied to tokens.
fixes#117448
For example unnecessary imports in std::prelude that can be eliminated:
```rust
use std::option::Option::Some;//~ WARNING the item `Some` is imported redundantly
use std::option::Option::None; //~ WARNING the item `None` is imported redundantly
```
Jonathan Brouwer