Prior to this PR, when we aborted because a "critical pass" failed, we
displayed the number of errors from that critical pass. While that's the
number of errors that caused compilation to abort in *that place*,
that's not what people really want to know. Instead, always report the
total number of errors, and don't bother to track the number of errors
from the last pass that failed.
This changes the compiler driver API to handle errors more smoothly,
and therefore is a compiler-api-[breaking-change].
Fixes#42793.
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
|
```
This test is failing on nightly for unknown reasons, and my best guess is a
difference in grep versions which is interpreting symbols differently. For now
let's just move this to a ui test and hope it fixes nightlies.
