Add line numbers and columns to error messages spanning multiple files
If an error message is emitted that spans several files, only the
primary file currently has line and column data attached. This is
useful information, even in files other than the one in which the error
occurs. We can often work out which line and column the error
corresponds to in other files — in this case it is helpful to add them
(in the case of ambiguity, the first relevant line/column is picked,
which is still helpful than none).
For E0277 on `for` loops, point at the "head" expression
When E0277's span points at a `for` loop, the actual issue is in the
element being iterated. Instead of pointing at the entire loop, point
only at the first line (when possible) so that the span ends in the
element for which E0277 was triggered.
If an error message is emitted that spans several files, only the
primary file currently has line and column data attached. This is
useful information, even in files other than the one in which the error
occurs. We can often work out which line and column the error
corresponds to in other files — in this case it is helpful to add them
(in the case of ambiguity, the first relevant line/column is picked,
which is still helpful than none).
fix mispositioned span
This fixes#47377
The output now looks like this
```
error[E0369]: binary operation `+` cannot be applied to type `&str`
--> h.rs:3:11
|
3 | let _a = b + ", World!";
| ^^^^^^^^^^^^^^ `+` can't be used to concatenate two `&str` strings
help: `to_owned()` can be used to create an owned `String` from a string reference. String concatenation appends the string on the right to the string on the left and may require reallocation. This requires ownership of the string on the left
|
3 | let _a = b.to_owned() + ", World!";
| ^^^^^^^^^
error: aborting due to previous error
```
For the case when emojis are involved, it gives the new output for proper indentation.
But for an indentation as follows,
```
fn main() {
let b = "hello";
let _a = b + ", World!";
}
```
it still mispositions the span
```
3 | println!("🦀🦀🦀🦀🦀"); let _a = b + ", World!";
| ^^^^^^^^^^^^^^ `+` can't be used to concatenate two `&str` strings
|
3 | println!("🦀🦀🦀🦀🦀"); let _a = b.to_owned() + ", World!";
| ^^^^^^^
error: aborting due to previous erro
```
cc @estebank @est31
Use correct line offsets for doctests
Not yet tested.
This doesn't handle char positions. It could if I collected a map of char offsets and lines, but this is a bit more work and requires hooking into the parser much more (unsure if it's possible).
r? @QuietMisdreavus
(fixes#45868)
Display `\t` in diagnostics code as four spaces
Follow up to #44386 using the unicode variable width machinery from #45711 to replace tabs in the source code when displaying a diagnostic error with four spaces (instead of only one), while properly accounting for this when calculating underlines.
Partly addresses #44618.
Refactor internal suggestion API
~~The only functional change is that whitespace, which is suggested to be added, also gets `^^^^` under it. An example is shown in the tests (the only test that changed).~~
Continuation of #41876
r? @nagisa
the changes are probably best viewed [without whitespace](https://github.com/rust-lang/rust/pull/45741/files?w=1)
Don't emit the same compiler diagnostic twice.
This PR makes the compiler filter out diagnostic messages that have already been emitted during the same compilation session.
Fixes#38384
Most of the Rust community uses 4 spaces for indentation,
but there are also tab users of Rust (including myself!).
This patch fixes a bug in error printing which mispositions
error indicators when near code with tabs.
The code attempted to fix the issue by replacing spaces
with tabs, but it sadly wasn't enough, as sometimes
you may not print spaces but _ or ^ instead.
This patch employs the reverse strategy: it replaces each
tab with a space, so that the number of _ and ^ and spaces
in error indicators below the code snippet line up
perfectly.
In a study [1] preceeding this patch, we could see that
this strategy is also chosen by gcc version 6.3.0.
Its not perfect, as the output is not beautiful, but its
the easiest to implement. If anyone wants to improve on
this, be my guest! This patch is meant as improvement of
the status quo, not as perfect end status. It fixes the
actual issue of mispositioning error indicators.
[1]: https://github.com/rust-lang/rust/issues/38384#issuecomment-326813710
Initial diagnostic API for proc-macros.
This commit introduces the ability to create and emit `Diagnostic` structures from proc-macros, allowing for proc-macro authors to emit warning, error, note, and help messages just like the compiler does.
The API is somewhat based on the diagnostic API already present in `rustc` with several changes that improve usability. The entry point into the diagnostic API is a new `Diagnostic` type which is primarily created through new `error`, `warning`, `help`, and `note` methods on `Span`. The `Diagnostic` type records the diagnostic level, message, and optional `Span` for the top-level diagnostic and contains a `Vec` of all of the child diagnostics. Child diagnostics can be added through builder methods on `Diagnostic`.
A typical use of the API may look like:
```rust
let token = parse_token();
let val = parse_val();
val.span
.error(format!("expected A but found {}", val))
.span_note(token.span, "because of this token")
.help("consider using a different token")
.emit();
```
cc @jseyfried @nrc @dtolnay @alexcrichton
Make fields of `Span` private
I actually tried to intern spans and benchmark the result<sup>*</sup>, and this was a prerequisite.
This kind of encapsulation will be a prerequisite for any other attempt to compress span's representation, so I decided to submit this change alone.
The issue https://github.com/rust-lang/rust/issues/43088 seems relevant, but it looks like `SpanId` won't be able to reuse this interface, unless the tables are global (like interner that I tried) and are not a part of HIR.
r? @michaelwoerister anyway
<sup>*</sup> Interning means 2-3 times more space is required for a single span, but duplicates are free. In practice it turned out that duplicates are not *that* common, so more memory was wasted by interning rather than saved.
