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.
This commit introduces a `Limit` type which is used to ensure that all
comparisons against limits within the compiler are consistent (which can
result in ICEs if they aren't).
Signed-off-by: David Wood <david@davidtw.co>
NLL has increased precision in its analysis of drop order, and we want
the test annotations to deliberately reflect this by having fewer
ERROR annotations for NLL than for AST-borrowck. The best way to get
this effect is via `// revisions`.
As a drive-by, also added uses of all the borrows just to make it
clear that NLL isn't somehow sidestepping things by using shorter
borrows than you might have otherwise expected. (Of course, the added
uses do not make all that much difference since the relevant types all
declare `impl Drop` and thus those drops have implicit uses anyway.)
This gives at least some explanation for why a borrow is expected to
last for a certain free region. Also:
* Reports E0373: "closure may outlive the current function" with NLL.
* Special cases the case of returning a reference to (or value
referencing) a local variable or temporary (E0515).
* Special case assigning a reference to a local variable in a closure
to a captured variable.
When dropping a self-borrowing struct we shouldn't add a "values in a
scope are dropped in the opposite order they are defined" message,
since there is only one value being dropped.
NOTE: I was careful to make each change in a manner that preserves the
existing diagnostic output (usually by ensuring that no lines were
added or removed). This means that the resulting source files are not
as nice to read as they were at the start. But we will have to review
these cases by hand anyway as follow-up work, so cleanup could
reasonably happen then (or not at all).
When a span starts on a line with nothing but whitespace to the left,
and there are no other annotations in that line, simplify the visual
representation of the span.
Go from:
```rust
error[E0072]: recursive type `A` has infinite size
--> file2.rs:1:1
|
1 | struct A {
| _^ starting here...
2 | | a: A,
3 | | }
| |_^ ...ending here: recursive type has infinite size
|
```
To:
```rust
error[E0072]: recursive type `A` has infinite size
--> file2.rs:1:1
|
1 | / struct A {
2 | | a: A,
3 | | }
| |_^ recursive type has infinite size
```
Remove `starting here...`/`...ending here` labels from all multiline
diagnostics.
When dealing with multiline spans that span few lines, show the complete
span instead of restricting to the first character of the first line.
For example, instead of:
```
% ./rustc foo.rs
error[E0277]: the trait bound `{integer}: std::ops::Add<()>` is not satisfied
--> foo.rs:13:9
|
13 | foo(1 + bar(x,
| ^ trait `{integer}: std::ops::Add<()>` not satisfied
|
```
show
```
% ./rustc foo.rs
error[E0277]: the trait bound `{integer}: std::ops::Add<()>` is not satisfied
--> foo.rs:13:9
|
13 | foo(1 + bar(x,
| ________^ starting here...
14 | | y),
| |_____________^ ...ending here: trait `{integer}: std::ops::Add<()>` not satisfied
|
```
