bjoernager/rust
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Handle _ properly in a couple of places.

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Currently (PatKind::Wild` (i.e. `_`) gets turned by
`lower_fn_params_to_names` into an empty identifier, which means it is
printed incorrectly by HIR pretty printing.

And likewise for `lower_fn_params_to_names`, which affects some error
messages.

This commit fixes them. This requires a slight tweak in a couple of
places to continue using parameter numbers in some error messages. And
it improves the output of `tests/ui/typeck/cyclic_type_ice.rs`:
`/* _ */` is a better suggestion than `/*  */`.
This commit is contained in:
Nicholas Nethercote 2025-03-14 08:40:43 +11:00
parent 9714f60f1d
commit 958bc7b365
6 changed files with 34 additions and 14 deletions
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3
compiler/rustc_middle/src/hir/map.rs
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@ -281,8 +281,9 @@ impl<'tcx> TyCtxt<'tcx> {
}
pub fn hir_body_param_names(self, id: BodyId) -> impl Iterator<Item = Ident> {
self.hir_body(id).params.iter().map(|arg| match arg.pat.kind {
self.hir_body(id).params.iter().map(|param| match param.pat.kind {
PatKind::Binding(_, _, ident, _) => ident,
PatKind::Wild => Ident::new(kw::Underscore, param.pat.span),
_ => Ident::empty(),
})
}