E0060 and E0061 improvement

[GuillaumeGomez]

Fixes #35290.

r? @jonathandturner

[sophiajt]

If we're going to make this a label, can we make it smaller? Maybe something like it simply:

"parameter type{} expected: {}"

Makes we wish we had a span_label for the definition site, so they could see where the requirements were coming from (if we don't have that already)

[GuillaumeGomez]

What about my proposition of list? A type a line if more than one type and it makes a nice output, easy to read. What do you think about it?

[sophiajt]

A list in the label or in a note? I think it would work better in the note. Do you have an heuristic in mind?

[GuillaumeGomez]

Not really. I can try both and show the result in here if you want.

[sophiajt]

Showing here sounds good

[GuillaumeGomez]

First test with list in the span message:

./x86_64-unknown-linux-gnu/stage1/bin/rustc src/test/compile-fail/E0061.rs
error[E0061]: this function takes 2 parameters but 1 parameter was supplied
  --> src/test/compile-fail/E0061.rs:14:5
   |
14 |     f(0);
   |     ^^^^ the following parameter types were expected: 
* u16
* &str

error: aborting due to previous error

Not very beautiful.

[GuillaumeGomez]

And inside a note it gives:

./x86_64-unknown-linux-gnu/stage1/bin/rustc src/test/compile-fail/E0061.rs
error[E0061]: this function takes 2 parameters but 1 parameter was supplied
  --> src/test/compile-fail/E0061.rs:14:5
   |
14 |     f(0);
   |     ^^^^
   |
   = note: the following parameter types were expected: 
* u16
* &str

error: aborting due to previous error

Not very beautiful either...

I think that the errors should keep the indent if there is a newline. If you want I can add it @jonathandturner.

[sophiajt]

Maybe:

./x86_64-unknown-linux-gnu/stage1/bin/rustc src/test/compile-fail/E0061.rs
error[E0061]: this function takes 2 parameters but 1 parameter was supplied
  --> src/test/compile-fail/E0061.rs:14:5
   |
14 |     f(0);
   |     ^^^^
   |
   = note: the following parameter types were expected:
   = note:   (u16, &str)

[sophiajt]

Another alternative (after chatting on IRC) might be:

error[E0061]: this function takes 2 parameters but 1 parameter was supplied
  --> src/test/compile-fail/E0061.rs:14:5
   |
11 | fn f(a: u16, b: &str) {}
   | - when calling this function
...
14 |     f(0);
   |     ^^^^ expected 2 parameters
   |

I wish we could point at the function name in the definition, but iirc, that span isn't yet available.

[GuillaumeGomez]

Updated.

[sophiajt]

Tidy failure:

/build/src/test/compile-fail/variadic-ffi-3.rs:20: tab character

[GuillaumeGomez]

Updated.

[sophiajt]

Sigh, this one got worse. I wish I'd fixed the type variable names also. Once they're fixed, this should look better

[sophiajt]

@bors r+ rollup

[bors]

📌 Commit 1eda14e has been approved by jonathandturner

[acrrd]

This broke the non bonus part of #35214

Edit: moving the err.span_label out of the if chain fix it