Don’t report missing fields in struct exprs with syntax errors.

[kpreid]

@Noratrieb told me that “it is a bug if this recovery causes follow-up errors that would not be there if the user fixed the first error.” So, here’s a contribution to hide a follow-up error that annoyed me recently.

Specifically, if the user writes a struct literal with a syntax error, such as

StructName { foo: 1 bar: 2 }

the compiler will no longer report that the field bar is missing in addition to the syntax error.

This is my first time attempting any change to the parser or AST; please let me know if there is a better way to do what I’ve done here. The part I’m least happy with is the blast radius of adding another field to hir::ExprKind::Struct, but this seems to be in line with the style of the rest of the code. (If this were my own code, I would consider changing hir::ExprKind::Struct to a nested struct, the same way it is in ast::ExprKind.)

[rustbot]

Some changes occurred in need_type_info.rs

cc @lcnr

Some changes occurred in src/tools/rustfmt

cc @rust-lang/rustfmt

Some changes occurred in src/tools/clippy

cc @rust-lang/clippy

[rustbot]

r? @JohnTitor

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[kpreid]

The only changes to rustfmt and clippy are necessary added _ patterns.

@rustbot label -T-clippy -T-rustfmt

[Noratrieb]

Thanks, these types of fixes are exactly what I was talking about!
An alternative that's less "infectious" would be to recover the invalid struct expr into an error expr, but that'd lose out on the correct fields, so I think this approach is good too.
I won't have time to review it in detail though, so I'll leave that to others.

[fmease]

Size increase of not uncommonly used AST & HIR nodes. @bors try @rust-timer queue

[rust-timer]

Awaiting bors try build completion.

@rustbot label: +S-waiting-on-perf

[rust-bors]

⌛ Trying commit c6432b7 with merge 4e1e63f…

To cancel the try build, run the command @bors try cancel.

Workflow: https://github.com/rust-lang/rust/actions/runs/22529605508

[fmease]

Alternatively to all of this we could 'just' make the parser recovery smarter and try to recover $path { $ident: $expr $ident: $expr } (and similar) as $path { $ident: $expr, $ident: $expr } instead of $path { $ident: /*error*/ } which is what we currently seem to do.