Suggest tuple struct syntax when using struct incorrectly

[estebank]

As per #57047 (comment), when encountering a tuple struct being used with the wrong syntax, suggest an appropriate fix:

error[E0560]: struct `NonCopyable` has no field named `p`
  --> $DIR/issue-4736.rs:4:26
   |
LL |     let z = NonCopyable{ p: () }; //~ ERROR struct `NonCopyable` has no field named `p`
   |             -------------^-----
   |             |            |
   |             |            field does not exist
   |             help: `NonCopyable` is a tuple struct, use the appropriate syntax: `NonCopyable(())`

instead of

error[E0560]: struct `NonCopyable` has no field named `p`
  --> $DIR/issue-4736.rs:4:26
   |
LL |     let z = NonCopyable{ p: () }; //~ ERROR struct `NonCopyable` has no field named `p`
   |                          ^ help: a field with a similar name exists: `0`

[Electron-libre]

Hi,

I can give it a try. This does not seems hard to fix.

Probably from here:

rust/src/librustc_typeck/check/mod.rs

Line 3622 in 8e948df

fn report_unknown_field(

• 1 Unit test

Should be enought

[estebank]

@Electron-libre that'd be great!

You'll have to look at the AdtDef's (only) variant in variants, which is of type VariantDef, and look at its ctor_kind field (of type CtorKind) to identify whether this is a struct or tuple style struct. From there it is a matter of using the appropriate spans for the suggestion and silencing the "similar name exists" suggestion.

To test your changes you can use ./x.py test src/test/ui --stage 1, and once you're happy with the results you can run the same command with --bless to update the stderr files.

[Electron-libre]

Thanks for the tips.

[JohnTitor]

@estebank this can be closed? It seems fixed in #61782.